From 2fc8e67b846e138dedc641380778f58a2d5aa159 Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Fri, 5 Feb 2021 19:11:48 +0100
Subject: [PATCH 01/14] :truck: Move mapColumn to expressions plugin

---
 .../expression_functions/specs/index.ts       |   3 +
 .../expression_functions/specs/map_column.ts  | 124 +++++++++++
 .../specs/tests/map_column.test.ts            | 124 +++++++++++
 .../expression_functions/specs/tests/utils.ts | 201 ++++++++++++++++++
 .../functions/common/index.ts                 |   2 -
 .../functions/common/mapColumn.test.js        |  69 ------
 .../functions/common/mapColumn.ts             |  79 -------
 .../canvas/i18n/functions/dict/map_column.ts  |  68 +++---
 .../canvas/i18n/functions/function_help.ts    |   2 -
 9 files changed, 490 insertions(+), 182 deletions(-)
 create mode 100644 src/plugins/expressions/common/expression_functions/specs/map_column.ts
 create mode 100644 src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
 delete mode 100644 x-pack/plugins/canvas/canvas_plugin_src/functions/common/mapColumn.test.js
 delete mode 100644 x-pack/plugins/canvas/canvas_plugin_src/functions/common/mapColumn.ts

diff --git a/src/plugins/expressions/common/expression_functions/specs/index.ts b/src/plugins/expressions/common/expression_functions/specs/index.ts
index 938fce026027c..cf0ada2f7f5e9 100644
--- a/src/plugins/expressions/common/expression_functions/specs/index.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/index.ts
@@ -15,6 +15,7 @@ import { theme } from './theme';
 import { cumulativeSum } from './cumulative_sum';
 import { derivative } from './derivative';
 import { movingAverage } from './moving_average';
+import { mapColumn } from './map_column';
 
 export const functionSpecs: AnyExpressionFunctionDefinition[] = [
   clog,
@@ -25,6 +26,7 @@ export const functionSpecs: AnyExpressionFunctionDefinition[] = [
   cumulativeSum,
   derivative,
   movingAverage,
+  mapColumn,
 ];
 
 export * from './clog';
@@ -35,3 +37,4 @@ export * from './theme';
 export * from './cumulative_sum';
 export * from './derivative';
 export * from './moving_average';
+export * from './map_column';
diff --git a/src/plugins/expressions/common/expression_functions/specs/map_column.ts b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
new file mode 100644
index 0000000000000..a77bed99f9492
--- /dev/null
+++ b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
@@ -0,0 +1,124 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { i18n } from '@kbn/i18n';
+import { ExpressionFunctionDefinition } from '../types';
+import { Datatable, getType } from '../../expression_types';
+
+export interface MapColumnArguments {
+  id?: string | null;
+  name: string;
+  expression?: (datatable: Datatable) => Promise<boolean | number | string | null>;
+  copyMetaFrom?: string | null;
+}
+
+export const mapColumn: ExpressionFunctionDefinition<
+  'mapColumn',
+  Datatable,
+  MapColumnArguments,
+  Promise<Datatable>
+> = {
+  name: 'mapColumn',
+  aliases: ['mc'], // midnight commander. So many times I've launched midnight commander instead of moving a file.
+  type: 'datatable',
+  inputTypes: ['datatable'],
+  help: i18n.translate('expressions.functions.mapColumnHelpText', {
+    defaultMessage:
+      'Adds a column calculated as the result of other columns. ' +
+      'Changes are made only when you provide arguments.' +
+      'See also {alterColumnFn} and {staticColumnFn}.',
+    values: {
+      alterColumnFn: '`alterColumn`',
+      staticColumnFn: '`staticColumn`',
+    },
+  }),
+  args: {
+    id: {
+      types: ['string', 'null'],
+      help: i18n.translate('expressions.functions.mapColumn.args.idHelpText', {
+        defaultMessage:
+          'An optional id of the resulting column. When `null` the name/column argument is used as id.',
+      }),
+      required: false,
+      default: null,
+    },
+    name: {
+      types: ['string'],
+      aliases: ['_', 'column'],
+      help: i18n.translate('expressions.functions.mapColumn.args.nameHelpText', {
+        defaultMessage: 'The name of the resulting column.',
+      }),
+      required: true,
+    },
+    expression: {
+      types: ['boolean', 'number', 'string', 'null'],
+      resolve: false,
+      aliases: ['exp', 'fn', 'function'],
+      help: i18n.translate('expressions.functions.mapColumn.args.expressionHelpText', {
+        defaultMessage:
+          'A {CANVAS} expression that is passed to each row as a single row {DATATABLE}.',
+        values: {
+          CANVAS: 'canvas',
+          DATATABLE: '`datatable`',
+        },
+      }),
+      required: true,
+    },
+    copyMetaFrom: {
+      types: ['string', 'null'],
+      help: i18n.translate('expressions.functions.mapColumn.args.copyMetaFromHelpText', {
+        defaultMessage:
+          "if set, the meta object from the specified column id is copied over to the specified target column. Throws an exception of the column doesn't exist",
+      }),
+      required: false,
+      default: null,
+    },
+  },
+  fn: (input, args) => {
+    const expression = args.expression || (() => Promise.resolve(null));
+    const columnId = args.id != null ? args.id : args.name;
+
+    const columns = [...input.columns];
+    const rowPromises = input.rows.map((row) => {
+      return expression({
+        type: 'datatable',
+        columns,
+        rows: [row],
+      }).then((val) => ({
+        ...row,
+        [columnId]: val,
+      }));
+    });
+
+    return Promise.all(rowPromises).then((rows) => {
+      const existingColumnIndex = columns.findIndex(({ name }) => name === args.name);
+      const type = rows.length ? getType(rows[0][args.name]) : 'null';
+      const newColumn = {
+        id: columnId,
+        name: args.name,
+        meta: { type },
+      };
+      if (args.copyMetaFrom) {
+        const metaSourceFrom = columns.find(({ name }) => name === args.copyMetaFrom);
+        newColumn.meta = { ...newColumn.meta, ...(metaSourceFrom?.meta || {}) };
+      }
+
+      if (existingColumnIndex === -1) {
+        columns.push(newColumn);
+      } else {
+        columns[existingColumnIndex] = newColumn;
+      }
+
+      return {
+        type: 'datatable',
+        columns,
+        rows,
+      } as Datatable;
+    });
+  },
+};
diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
new file mode 100644
index 0000000000000..588d1f34590f3
--- /dev/null
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
@@ -0,0 +1,124 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { Datatable } from '../../../expression_types';
+import { mapColumn, MapColumnArguments } from '../map_column';
+import { emptyTable, functionWrapper, testTable } from './utils';
+
+const pricePlusTwo = (datatable: Datatable) => Promise.resolve(datatable.rows[0].price + 2);
+
+describe('mapColumn', () => {
+  const fn = functionWrapper(mapColumn);
+  const runFn = (input: Datatable, args: MapColumnArguments) =>
+    fn(input, args) as Promise<Datatable>;
+
+  it('returns a datatable with a new column with the values from mapping a function over each row in a datatable', () => {
+    return runFn(testTable, {
+      id: 'pricePlusTwo',
+      name: 'pricePlusTwo',
+      expression: pricePlusTwo,
+    }).then((result) => {
+      const arbitraryRowIndex = 2;
+
+      expect(result.type).toBe('datatable');
+      expect(result.columns).toEqual([
+        ...testTable.columns,
+        { id: 'pricePlusTwo', name: 'pricePlusTwo', meta: { type: 'number' } },
+      ]);
+      expect(result.columns[result.columns.length - 1]).toHaveProperty('name', 'pricePlusTwo');
+      expect(result.rows[arbitraryRowIndex]).toHaveProperty('pricePlusTwo');
+    });
+  });
+
+  it('overwrites existing column with the new column if an existing column name is provided', () => {
+    return runFn(testTable, { name: 'name', expression: pricePlusTwo }).then((result) => {
+      const nameColumnIndex = result.columns.findIndex(({ name }) => name === 'name');
+      const arbitraryRowIndex = 4;
+
+      expect(result.type).toBe('datatable');
+      expect(result.columns).toHaveLength(testTable.columns.length);
+      expect(result.columns[nameColumnIndex]).toHaveProperty('name', 'name');
+      expect(result.columns[nameColumnIndex].meta).toHaveProperty('type', 'number');
+      expect(result.rows[arbitraryRowIndex]).toHaveProperty('name', 202);
+    });
+  });
+
+  it('adds a column to empty tables', () => {
+    return runFn(emptyTable, { name: 'name', expression: pricePlusTwo }).then((result) => {
+      expect(result.type).toBe('datatable');
+      expect(result.columns).toHaveLength(1);
+      expect(result.columns[0]).toHaveProperty('name', 'name');
+      expect(result.columns[0].meta).toHaveProperty('type', 'null');
+    });
+  });
+
+  it('should assign specific id, different from name, when id arg is passed for new columns', () => {
+    return runFn(emptyTable, { name: 'name', id: 'myid', expression: pricePlusTwo }).then(
+      (result) => {
+        expect(result.type).toBe('datatable');
+        expect(result.columns).toHaveLength(1);
+        expect(result.columns[0]).toHaveProperty('name', 'name');
+        expect(result.columns[0]).toHaveProperty('id', 'myid');
+        expect(result.columns[0].meta).toHaveProperty('type', 'null');
+      }
+    );
+  });
+
+  it('should assign specific id, different from name, when id arg is passed for copied column', () => {
+    return runFn(testTable, { name: 'name', id: 'myid', expression: pricePlusTwo }).then(
+      (result) => {
+        const nameColumnIndex = result.columns.findIndex(({ name }) => name === 'name');
+        expect(result.type).toBe('datatable');
+        expect(result.columns[nameColumnIndex]).toEqual({
+          id: 'myid',
+          name: 'name',
+          meta: { type: 'string' },
+        });
+      }
+    );
+  });
+
+  it('should copy over the meta information from the specified column', () => {
+    return runFn(testTable, { name: 'name', copyMetaFrom: 'time', expression: pricePlusTwo }).then(
+      (result) => {
+        const nameColumnIndex = result.columns.findIndex(({ name }) => name === 'name');
+        expect(result.type).toBe('datatable');
+        expect(result.columns[nameColumnIndex]).toEqual({
+          id: 'name',
+          name: 'name',
+          meta: { type: 'date' },
+        });
+      }
+    );
+  });
+
+  it('should be resilient if the references column for meta information does not exists', () => {
+    return runFn(emptyTable, { name: 'name', copyMetaFrom: 'time', expression: pricePlusTwo }).then(
+      (result) => {
+        expect(result.type).toBe('datatable');
+        expect(result.columns).toHaveLength(1);
+        expect(result.columns[0]).toHaveProperty('name', 'name');
+        expect(result.columns[0]).toHaveProperty('id', 'name');
+        expect(result.columns[0].meta).toHaveProperty('type', 'null');
+      }
+    );
+  });
+
+  describe('expression', () => {
+    it('maps null values to the new column', () => {
+      return runFn(testTable, { name: 'empty' }).then((result) => {
+        const emptyColumnIndex = result.columns.findIndex(({ name }) => name === 'empty');
+        const arbitraryRowIndex = 8;
+
+        expect(result.columns[emptyColumnIndex]).toHaveProperty('name', 'empty');
+        expect(result.columns[emptyColumnIndex].meta).toHaveProperty('type', 'null');
+        expect(result.rows[arbitraryRowIndex]).toHaveProperty('empty', null);
+      });
+    });
+  });
+});
diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/utils.ts b/src/plugins/expressions/common/expression_functions/specs/tests/utils.ts
index 9006de9067616..44ed87dc02360 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/utils.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/utils.ts
@@ -9,6 +9,7 @@
 import { mapValues } from 'lodash';
 import { AnyExpressionFunctionDefinition } from '../../types';
 import { ExecutionContext } from '../../../execution/types';
+import { Datatable } from '../../../expression_types';
 
 /**
  * Takes a function spec and passes in default args,
@@ -22,3 +23,203 @@ export const functionWrapper = (spec: AnyExpressionFunctionDefinition) => {
     handlers: ExecutionContext = {} as ExecutionContext
   ) => spec.fn(context, { ...defaultArgs, ...args }, handlers);
 };
+
+const emptyTable: Datatable = {
+  type: 'datatable',
+  columns: [],
+  rows: [],
+};
+
+const testTable: Datatable = {
+  type: 'datatable',
+  columns: [
+    {
+      id: 'name',
+      name: 'name',
+      meta: { type: 'string' },
+    },
+    {
+      id: 'time',
+      name: 'time',
+      meta: { type: 'date' },
+    },
+    {
+      id: 'price',
+      name: 'price',
+      meta: { type: 'number' },
+    },
+    {
+      id: 'quantity',
+      name: 'quantity',
+      meta: { type: 'number' },
+    },
+    {
+      id: 'in_stock',
+      name: 'in_stock',
+      meta: { type: 'boolean' },
+    },
+  ],
+  rows: [
+    {
+      name: 'product1',
+      time: 1517842800950, // 05 Feb 2018 15:00:00 GMT
+      price: 605,
+      quantity: 100,
+      in_stock: true,
+    },
+    {
+      name: 'product1',
+      time: 1517929200950, // 06 Feb 2018 15:00:00 GMT
+      price: 583,
+      quantity: 200,
+      in_stock: true,
+    },
+    {
+      name: 'product1',
+      time: 1518015600950, // 07 Feb 2018 15:00:00 GMT
+      price: 420,
+      quantity: 300,
+      in_stock: true,
+    },
+    {
+      name: 'product2',
+      time: 1517842800950, // 05 Feb 2018 15:00:00 GMT
+      price: 216,
+      quantity: 350,
+      in_stock: false,
+    },
+    {
+      name: 'product2',
+      time: 1517929200950, // 06 Feb 2018 15:00:00 GMT
+      price: 200,
+      quantity: 256,
+      in_stock: false,
+    },
+    {
+      name: 'product2',
+      time: 1518015600950, // 07 Feb 2018 15:00:00 GMT
+      price: 190,
+      quantity: 231,
+      in_stock: false,
+    },
+    {
+      name: 'product3',
+      time: 1517842800950, // 05 Feb 2018 15:00:00 GMT
+      price: 67,
+      quantity: 240,
+      in_stock: true,
+    },
+    {
+      name: 'product4',
+      time: 1517842800950, // 05 Feb 2018 15:00:00 GMT
+      price: 311,
+      quantity: 447,
+      in_stock: false,
+    },
+    {
+      name: 'product5',
+      time: 1517842800950, // 05 Feb 2018 15:00:00 GMT
+      price: 288,
+      quantity: 384,
+      in_stock: true,
+    },
+  ],
+};
+
+const stringTable: Datatable = {
+  type: 'datatable',
+  columns: [
+    {
+      id: 'name',
+      name: 'name',
+      meta: { type: 'string' },
+    },
+    {
+      id: 'time',
+      name: 'time',
+      meta: { type: 'string' },
+    },
+    {
+      id: 'price',
+      name: 'price',
+      meta: { type: 'string' },
+    },
+    {
+      id: 'quantity',
+      name: 'quantity',
+      meta: { type: 'string' },
+    },
+    {
+      id: 'in_stock',
+      name: 'in_stock',
+      meta: { type: 'string' },
+    },
+  ],
+  rows: [
+    {
+      name: 'product1',
+      time: '2018-02-05T15:00:00.950Z',
+      price: '605',
+      quantity: '100',
+      in_stock: 'true',
+    },
+    {
+      name: 'product1',
+      time: '2018-02-06T15:00:00.950Z',
+      price: '583',
+      quantity: '200',
+      in_stock: 'true',
+    },
+    {
+      name: 'product1',
+      time: '2018-02-07T15:00:00.950Z',
+      price: '420',
+      quantity: '300',
+      in_stock: 'true',
+    },
+    {
+      name: 'product2',
+      time: '2018-02-05T15:00:00.950Z',
+      price: '216',
+      quantity: '350',
+      in_stock: 'false',
+    },
+    {
+      name: 'product2',
+      time: '2018-02-06T15:00:00.950Z',
+      price: '200',
+      quantity: '256',
+      in_stock: 'false',
+    },
+    {
+      name: 'product2',
+      time: '2018-02-07T15:00:00.950Z',
+      price: '190',
+      quantity: '231',
+      in_stock: 'false',
+    },
+    {
+      name: 'product3',
+      time: '2018-02-05T15:00:00.950Z',
+      price: '67',
+      quantity: '240',
+      in_stock: 'true',
+    },
+    {
+      name: 'product4',
+      time: '2018-02-05T15:00:00.950Z',
+      price: '311',
+      quantity: '447',
+      in_stock: 'false',
+    },
+    {
+      name: 'product5',
+      time: '2018-02-05T15:00:00.950Z',
+      price: '288',
+      quantity: '384',
+      in_stock: 'true',
+    },
+  ],
+};
+
+export { emptyTable, testTable, stringTable };
diff --git a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/index.ts b/x-pack/plugins/canvas/canvas_plugin_src/functions/common/index.ts
index 048bc3468f149..a00718fce0797 100644
--- a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/index.ts
+++ b/x-pack/plugins/canvas/canvas_plugin_src/functions/common/index.ts
@@ -34,7 +34,6 @@ import { joinRows } from './join_rows';
 import { lt } from './lt';
 import { lte } from './lte';
 import { mapCenter } from './map_center';
-import { mapColumn } from './mapColumn';
 import { math } from './math';
 import { metric } from './metric';
 import { neq } from './neq';
@@ -89,7 +88,6 @@ export const functions = [
   lte,
   joinRows,
   mapCenter,
-  mapColumn,
   math,
   metric,
   neq,
diff --git a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/mapColumn.test.js b/x-pack/plugins/canvas/canvas_plugin_src/functions/common/mapColumn.test.js
deleted file mode 100644
index d511c7774122d..0000000000000
--- a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/mapColumn.test.js
+++ /dev/null
@@ -1,69 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License
- * 2.0; you may not use this file except in compliance with the Elastic License
- * 2.0.
- */
-
-import { functionWrapper } from '../../../test_helpers/function_wrapper';
-import { testTable, emptyTable } from './__fixtures__/test_tables';
-import { mapColumn } from './mapColumn';
-
-const pricePlusTwo = (datatable) => Promise.resolve(datatable.rows[0].price + 2);
-
-describe('mapColumn', () => {
-  const fn = functionWrapper(mapColumn);
-
-  it('returns a datatable with a new column with the values from mapping a function over each row in a datatable', () => {
-    return fn(testTable, {
-      id: 'pricePlusTwo',
-      name: 'pricePlusTwo',
-      expression: pricePlusTwo,
-    }).then((result) => {
-      const arbitraryRowIndex = 2;
-
-      expect(result.type).toBe('datatable');
-      expect(result.columns).toEqual([
-        ...testTable.columns,
-        { id: 'pricePlusTwo', name: 'pricePlusTwo', meta: { type: 'number' } },
-      ]);
-      expect(result.columns[result.columns.length - 1]).toHaveProperty('name', 'pricePlusTwo');
-      expect(result.rows[arbitraryRowIndex]).toHaveProperty('pricePlusTwo');
-    });
-  });
-
-  it('overwrites existing column with the new column if an existing column name is provided', () => {
-    return fn(testTable, { name: 'name', expression: pricePlusTwo }).then((result) => {
-      const nameColumnIndex = result.columns.findIndex(({ name }) => name === 'name');
-      const arbitraryRowIndex = 4;
-
-      expect(result.type).toBe('datatable');
-      expect(result.columns).toHaveLength(testTable.columns.length);
-      expect(result.columns[nameColumnIndex]).toHaveProperty('name', 'name');
-      expect(result.columns[nameColumnIndex].meta).toHaveProperty('type', 'number');
-      expect(result.rows[arbitraryRowIndex]).toHaveProperty('name', 202);
-    });
-  });
-
-  it('adds a column to empty tables', () => {
-    return fn(emptyTable, { name: 'name', expression: pricePlusTwo }).then((result) => {
-      expect(result.type).toBe('datatable');
-      expect(result.columns).toHaveLength(1);
-      expect(result.columns[0]).toHaveProperty('name', 'name');
-      expect(result.columns[0].meta).toHaveProperty('type', 'null');
-    });
-  });
-
-  describe('expression', () => {
-    it('maps null values to the new column', () => {
-      return fn(testTable, { name: 'empty' }).then((result) => {
-        const emptyColumnIndex = result.columns.findIndex(({ name }) => name === 'empty');
-        const arbitraryRowIndex = 8;
-
-        expect(result.columns[emptyColumnIndex]).toHaveProperty('name', 'empty');
-        expect(result.columns[emptyColumnIndex].meta).toHaveProperty('type', 'null');
-        expect(result.rows[arbitraryRowIndex]).toHaveProperty('empty', null);
-      });
-    });
-  });
-});
diff --git a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/mapColumn.ts b/x-pack/plugins/canvas/canvas_plugin_src/functions/common/mapColumn.ts
deleted file mode 100644
index 63cc0d6cbc687..0000000000000
--- a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/mapColumn.ts
+++ /dev/null
@@ -1,79 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License
- * 2.0; you may not use this file except in compliance with the Elastic License
- * 2.0.
- */
-
-import { Datatable, ExpressionFunctionDefinition, getType } from '../../../types';
-import { getFunctionHelp } from '../../../i18n';
-
-interface Arguments {
-  name: string;
-  expression: (datatable: Datatable) => Promise<boolean | number | string | null>;
-}
-
-export function mapColumn(): ExpressionFunctionDefinition<
-  'mapColumn',
-  Datatable,
-  Arguments,
-  Promise<Datatable>
-> {
-  const { help, args: argHelp } = getFunctionHelp().mapColumn;
-
-  return {
-    name: 'mapColumn',
-    aliases: ['mc'], // midnight commander. So many times I've launched midnight commander instead of moving a file.
-    type: 'datatable',
-    inputTypes: ['datatable'],
-    help,
-    args: {
-      name: {
-        types: ['string'],
-        aliases: ['_', 'column'],
-        help: argHelp.name,
-        required: true,
-      },
-      expression: {
-        types: ['boolean', 'number', 'string', 'null'],
-        resolve: false,
-        aliases: ['exp', 'fn', 'function'],
-        help: argHelp.expression,
-        required: true,
-      },
-    },
-    fn: (input, args) => {
-      const expression = args.expression || (() => Promise.resolve(null));
-
-      const columns = [...input.columns];
-      const rowPromises = input.rows.map((row) => {
-        return expression({
-          type: 'datatable',
-          columns,
-          rows: [row],
-        }).then((val) => ({
-          ...row,
-          [args.name]: val,
-        }));
-      });
-
-      return Promise.all(rowPromises).then((rows) => {
-        const existingColumnIndex = columns.findIndex(({ name }) => name === args.name);
-        const type = rows.length ? getType(rows[0][args.name]) : 'null';
-        const newColumn = { id: args.name, name: args.name, meta: { type } };
-
-        if (existingColumnIndex === -1) {
-          columns.push(newColumn);
-        } else {
-          columns[existingColumnIndex] = newColumn;
-        }
-
-        return {
-          type: 'datatable',
-          columns,
-          rows,
-        } as Datatable;
-      });
-    },
-  };
-}
diff --git a/x-pack/plugins/canvas/i18n/functions/dict/map_column.ts b/x-pack/plugins/canvas/i18n/functions/dict/map_column.ts
index f8d0311d08961..2dbd3ff5d7657 100644
--- a/x-pack/plugins/canvas/i18n/functions/dict/map_column.ts
+++ b/x-pack/plugins/canvas/i18n/functions/dict/map_column.ts
@@ -5,34 +5,42 @@
  * 2.0.
  */
 
-import { i18n } from '@kbn/i18n';
-import { mapColumn } from '../../../canvas_plugin_src/functions/common/mapColumn';
-import { FunctionHelp } from '../function_help';
-import { FunctionFactory } from '../../../types';
-import { CANVAS, DATATABLE } from '../../constants';
+// import { i18n } from '@kbn/i18n';
+// // import { mapColumn } from '../../../canvas_plugin_src/functions/common/mapColumn';
+// import { FunctionHelp } from '../function_help';
+// import { FunctionFactory } from '../../../types';
+// import { CANVAS, DATATABLE } from '../../constants';
 
-export const help: FunctionHelp<FunctionFactory<typeof mapColumn>> = {
-  help: i18n.translate('xpack.canvas.functions.mapColumnHelpText', {
-    defaultMessage:
-      'Adds a column calculated as the result of other columns. ' +
-      'Changes are made only when you provide arguments.' +
-      'See also {alterColumnFn} and {staticColumnFn}.',
-    values: {
-      alterColumnFn: '`alterColumn`',
-      staticColumnFn: '`staticColumn`',
-    },
-  }),
-  args: {
-    name: i18n.translate('xpack.canvas.functions.mapColumn.args.nameHelpText', {
-      defaultMessage: 'The name of the resulting column.',
-    }),
-    expression: i18n.translate('xpack.canvas.functions.mapColumn.args.expressionHelpText', {
-      defaultMessage:
-        'A {CANVAS} expression that is passed to each row as a single row {DATATABLE}.',
-      values: {
-        CANVAS,
-        DATATABLE,
-      },
-    }),
-  },
-};
+// export const help: FunctionHelp<FunctionFactory<typeof mapColumn>> = {
+//   help: i18n.translate('xpack.canvas.functions.mapColumnHelpText', {
+//     defaultMessage:
+//       'Adds a column calculated as the result of other columns. ' +
+//       'Changes are made only when you provide arguments.' +
+//       'See also {alterColumnFn} and {staticColumnFn}.',
+//     values: {
+//       alterColumnFn: '`alterColumn`',
+//       staticColumnFn: '`staticColumn`',
+//     },
+//   }),
+//   args: {
+//     id: i18n.translate('xpack.canvas.functions.mapColumn.args.idHelpText', {
+//       defaultMessage:
+//         'An optional id of the resulting column. When `null` the name/column argument is used as id.',
+//     }),
+//     name: i18n.translate('xpack.canvas.functions.mapColumn.args.nameHelpText', {
+//       defaultMessage: 'The name of the resulting column.',
+//     }),
+//     expression: i18n.translate('xpack.canvas.functions.mapColumn.args.expressionHelpText', {
+//       defaultMessage:
+//         'A {CANVAS} expression that is passed to each row as a single row {DATATABLE}.',
+//       values: {
+//         CANVAS,
+//         DATATABLE,
+//       },
+//     }),
+//     copyMetaFrom: i18n.translate('xpack.canvas.functions.mapColumn.args.copyMetaFromHelpText', {
+//       defaultMessage:
+//         "if set, the meta object from the specified column id is copied over to the specified target column. Throws an exception of the column doesn't exist",
+//     }),
+//   },
+// };
diff --git a/x-pack/plugins/canvas/i18n/functions/function_help.ts b/x-pack/plugins/canvas/i18n/functions/function_help.ts
index 245732e53cc89..87e6883e599ce 100644
--- a/x-pack/plugins/canvas/i18n/functions/function_help.ts
+++ b/x-pack/plugins/canvas/i18n/functions/function_help.ts
@@ -46,7 +46,6 @@ import { help as location } from './dict/location';
 import { help as lt } from './dict/lt';
 import { help as lte } from './dict/lte';
 import { help as mapCenter } from './dict/map_center';
-import { help as mapColumn } from './dict/map_column';
 import { help as markdown } from './dict/markdown';
 import { help as math } from './dict/math';
 import { help as metric } from './dict/metric';
@@ -209,7 +208,6 @@ export const getFunctionHelp = (): FunctionHelpDict => ({
   lt,
   lte,
   mapCenter,
-  mapColumn,
   markdown,
   math,
   metric,

From 96c3aae9ce2b0c9f615d186477a0ed8e26b74aaf Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Mon, 15 Feb 2021 14:51:05 +0100
Subject: [PATCH 02/14] :globe_with_meridians: Fix i18n for mapColumns

---
 .../canvas/i18n/functions/dict/map_column.ts  | 46 -------------------
 .../translations/translations/ja-JP.json      |  3 --
 .../translations/translations/zh-CN.json      |  3 --
 3 files changed, 52 deletions(-)
 delete mode 100644 x-pack/plugins/canvas/i18n/functions/dict/map_column.ts

diff --git a/x-pack/plugins/canvas/i18n/functions/dict/map_column.ts b/x-pack/plugins/canvas/i18n/functions/dict/map_column.ts
deleted file mode 100644
index 2dbd3ff5d7657..0000000000000
--- a/x-pack/plugins/canvas/i18n/functions/dict/map_column.ts
+++ /dev/null
@@ -1,46 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License
- * 2.0; you may not use this file except in compliance with the Elastic License
- * 2.0.
- */
-
-// import { i18n } from '@kbn/i18n';
-// // import { mapColumn } from '../../../canvas_plugin_src/functions/common/mapColumn';
-// import { FunctionHelp } from '../function_help';
-// import { FunctionFactory } from '../../../types';
-// import { CANVAS, DATATABLE } from '../../constants';
-
-// export const help: FunctionHelp<FunctionFactory<typeof mapColumn>> = {
-//   help: i18n.translate('xpack.canvas.functions.mapColumnHelpText', {
-//     defaultMessage:
-//       'Adds a column calculated as the result of other columns. ' +
-//       'Changes are made only when you provide arguments.' +
-//       'See also {alterColumnFn} and {staticColumnFn}.',
-//     values: {
-//       alterColumnFn: '`alterColumn`',
-//       staticColumnFn: '`staticColumn`',
-//     },
-//   }),
-//   args: {
-//     id: i18n.translate('xpack.canvas.functions.mapColumn.args.idHelpText', {
-//       defaultMessage:
-//         'An optional id of the resulting column. When `null` the name/column argument is used as id.',
-//     }),
-//     name: i18n.translate('xpack.canvas.functions.mapColumn.args.nameHelpText', {
-//       defaultMessage: 'The name of the resulting column.',
-//     }),
-//     expression: i18n.translate('xpack.canvas.functions.mapColumn.args.expressionHelpText', {
-//       defaultMessage:
-//         'A {CANVAS} expression that is passed to each row as a single row {DATATABLE}.',
-//       values: {
-//         CANVAS,
-//         DATATABLE,
-//       },
-//     }),
-//     copyMetaFrom: i18n.translate('xpack.canvas.functions.mapColumn.args.copyMetaFromHelpText', {
-//       defaultMessage:
-//         "if set, the meta object from the specified column id is copied over to the specified target column. Throws an exception of the column doesn't exist",
-//     }),
-//   },
-// };
diff --git a/x-pack/plugins/translations/translations/ja-JP.json b/x-pack/plugins/translations/translations/ja-JP.json
index 4d94539a514d1..32b2c4b3cdc04 100644
--- a/x-pack/plugins/translations/translations/ja-JP.json
+++ b/x-pack/plugins/translations/translations/ja-JP.json
@@ -5980,9 +5980,6 @@
     "xpack.canvas.functions.ltHelpText": "{CONTEXT} が引数よりも小さいかを戻します。",
     "xpack.canvas.functions.mapCenter.args.latHelpText": "マップの中央の緯度",
     "xpack.canvas.functions.mapCenterHelpText": "マップの中央座標とズームレベルのオブジェクトに戻ります。",
-    "xpack.canvas.functions.mapColumn.args.expressionHelpText": "単一行 {DATATABLE} として各行に渡される {CANVAS} 表現です。",
-    "xpack.canvas.functions.mapColumn.args.nameHelpText": "結果の列の名前です。",
-    "xpack.canvas.functions.mapColumnHelpText": "他の列の結果として計算された列を追加します。引数が指定された場合のみ変更が加えられます。{alterColumnFn}と{staticColumnFn}もご参照ください。",
     "xpack.canvas.functions.markdown.args.contentHelpText": "{MARKDOWN} を含むテキストの文字列です。連結させるには、{stringFn} 関数を複数回渡します。",
     "xpack.canvas.functions.markdown.args.fontHelpText": "コンテンツの {CSS} フォントプロパティです。たとえば、{fontFamily} または {fontWeight} です。",
     "xpack.canvas.functions.markdown.args.openLinkHelpText": "新しいタブでリンクを開くためのtrue/false値。デフォルト値は「false」です。「true」に設定するとすべてのリンクが新しいタブで開くようになります。",
diff --git a/x-pack/plugins/translations/translations/zh-CN.json b/x-pack/plugins/translations/translations/zh-CN.json
index a35d4c67dde00..d9a1476d3fd02 100644
--- a/x-pack/plugins/translations/translations/zh-CN.json
+++ b/x-pack/plugins/translations/translations/zh-CN.json
@@ -5991,9 +5991,6 @@
     "xpack.canvas.functions.ltHelpText": "返回 {CONTEXT} 是否小于参数。",
     "xpack.canvas.functions.mapCenter.args.latHelpText": "地图中心的纬度",
     "xpack.canvas.functions.mapCenterHelpText": "返回包含地图中心坐标和缩放级别的对象。",
-    "xpack.canvas.functions.mapColumn.args.expressionHelpText": "作为单行 {DATATABLE} 传递到每一行的 {CANVAS} 表达式。",
-    "xpack.canvas.functions.mapColumn.args.nameHelpText": "结果列的名称。",
-    "xpack.canvas.functions.mapColumnHelpText": "添加计算为其他列的结果的列。只有提供参数时，才会执行更改。另请参见 {alterColumnFn} 和 {staticColumnFn}。",
     "xpack.canvas.functions.markdown.args.contentHelpText": "包含 {MARKDOWN} 的文本字符串。要进行串联，请多次传递 {stringFn} 函数。",
     "xpack.canvas.functions.markdown.args.fontHelpText": "内容的 {CSS} 字体属性。例如 {fontFamily} 或 {fontWeight}。",
     "xpack.canvas.functions.markdown.args.openLinkHelpText": "用于在新标签页中打开链接的 true 或 false 值。默认值为 `false`。设置为 `true` 时将在新标签页中打开所有链接。",

From 241aa03ddf72d66595a97ae501e0a9d60d15a589 Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Mon, 15 Feb 2021 15:27:36 +0100
Subject: [PATCH 03/14] :truck: Move over the math function to shared
 expressions plugin

---
 .../expression_functions/specs/index.ts       |   5 +-
 .../common/expression_functions/specs/math.ts | 136 ++++++++++++++++++
 .../specs/tests/math.test.ts                  |  15 +-
 .../expression_functions/specs/tests/utils.ts |   6 +-
 .../functions/common/index.ts                 |   2 -
 .../functions/common/math.ts                  |  70 ---------
 .../canvas/i18n/functions/dict/math.ts        |  69 ---------
 .../canvas/i18n/functions/function_errors.ts  |   2 -
 .../canvas/i18n/functions/function_help.ts    |   2 -
 9 files changed, 150 insertions(+), 157 deletions(-)
 create mode 100644 src/plugins/expressions/common/expression_functions/specs/math.ts
 rename x-pack/plugins/canvas/canvas_plugin_src/functions/common/math.test.js => src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts (89%)
 delete mode 100644 x-pack/plugins/canvas/canvas_plugin_src/functions/common/math.ts
 delete mode 100644 x-pack/plugins/canvas/i18n/functions/dict/math.ts

diff --git a/src/plugins/expressions/common/expression_functions/specs/index.ts b/src/plugins/expressions/common/expression_functions/specs/index.ts
index cf0ada2f7f5e9..9408b3a433712 100644
--- a/src/plugins/expressions/common/expression_functions/specs/index.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/index.ts
@@ -16,6 +16,7 @@ import { cumulativeSum } from './cumulative_sum';
 import { derivative } from './derivative';
 import { movingAverage } from './moving_average';
 import { mapColumn } from './map_column';
+import { math } from './math';
 
 export const functionSpecs: AnyExpressionFunctionDefinition[] = [
   clog,
@@ -27,6 +28,7 @@ export const functionSpecs: AnyExpressionFunctionDefinition[] = [
   derivative,
   movingAverage,
   mapColumn,
+  math,
 ];
 
 export * from './clog';
@@ -37,4 +39,5 @@ export * from './theme';
 export * from './cumulative_sum';
 export * from './derivative';
 export * from './moving_average';
-export * from './map_column';
+export { mapColumn, MapColumnArguments } from './map_column';
+export { math, MathArguments, MathInput } from './math';
diff --git a/src/plugins/expressions/common/expression_functions/specs/math.ts b/src/plugins/expressions/common/expression_functions/specs/math.ts
new file mode 100644
index 0000000000000..f963902c4b32f
--- /dev/null
+++ b/src/plugins/expressions/common/expression_functions/specs/math.ts
@@ -0,0 +1,136 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { map, zipObject } from 'lodash';
+import { i18n } from '@kbn/i18n';
+import { evaluate } from '@kbn/tinymath';
+import { ExpressionFunctionDefinition } from '../types';
+import { Datatable, isDatatable } from '../../expression_types';
+
+export interface MathArguments {
+  expression: string;
+}
+
+export type MathInput = number | Datatable;
+
+const TINYMATH = '`TinyMath`';
+const TINYMATH_URL =
+  'https://www.elastic.co/guide/en/kibana/current/canvas-tinymath-functions.html';
+
+const isString = (val: any): boolean => typeof val === 'string';
+
+function pivotObjectArray<
+  RowType extends { [key: string]: any },
+  ReturnColumns extends string | number | symbol = keyof RowType
+>(rows: RowType[], columns?: string[]): Record<string, ReturnColumns[]> {
+  const columnNames = columns || Object.keys(rows[0]);
+  if (!columnNames.every(isString)) {
+    throw new Error('Columns should be an array of strings');
+  }
+
+  const columnValues = map(columnNames, (name) => map(rows, name));
+  return zipObject(columnNames, columnValues);
+}
+
+export const errors = {
+  emptyExpression: () =>
+    new Error(
+      i18n.translate('expressions.functions.math.emptyExpressionErrorMessage', {
+        defaultMessage: 'Empty expression',
+      })
+    ),
+  tooManyResults: () =>
+    new Error(
+      i18n.translate('expressions.functions.math.tooManyResultsErrorMessage', {
+        defaultMessage:
+          'Expressions must return a single number. Try wrapping your expression in {mean} or {sum}',
+        values: {
+          mean: 'mean()',
+          sum: 'sum()',
+        },
+      })
+    ),
+  executionFailed: () =>
+    new Error(
+      i18n.translate('expressions.functions.math.executionFailedErrorMessage', {
+        defaultMessage: 'Failed to execute math expression. Check your column names',
+      })
+    ),
+  emptyDatatable: () =>
+    new Error(
+      i18n.translate('expressions.functions.math.emptyDatatableErrorMessage', {
+        defaultMessage: 'Empty datatable',
+      })
+    ),
+};
+
+export const math: ExpressionFunctionDefinition<'math', MathInput, MathArguments, number> = {
+  name: 'math',
+  type: 'number',
+  inputTypes: ['number', 'datatable'],
+  help: i18n.translate('expressions.functions.mathHelpText', {
+    defaultMessage:
+      'Interprets a {TINYMATH} math expression using a {TYPE_NUMBER} or {DATATABLE} as {CONTEXT}. ' +
+      'The {DATATABLE} columns are available by their column name. ' +
+      'If the {CONTEXT} is a number it is available as {value}.',
+    values: {
+      TINYMATH,
+      CONTEXT: '_context_',
+      DATATABLE: '`datatable`',
+      value: '`value`',
+      TYPE_NUMBER: '`number`',
+    },
+  }),
+  args: {
+    expression: {
+      aliases: ['_'],
+      types: ['string'],
+      help: i18n.translate('expressions.functions.math.args.expressionHelpText', {
+        defaultMessage: 'An evaluated {TINYMATH} expression. See {TINYMATH_URL}.',
+        values: {
+          TINYMATH,
+          TINYMATH_URL,
+        },
+      }),
+    },
+  },
+  fn: (input, args) => {
+    const { expression } = args;
+
+    if (!expression || expression.trim() === '') {
+      throw errors.emptyExpression();
+    }
+
+    const mathContext = isDatatable(input)
+      ? pivotObjectArray(
+          input.rows,
+          input.columns.map((col) => col.name)
+        )
+      : { value: input };
+
+    try {
+      const result = evaluate(expression, mathContext);
+      if (Array.isArray(result)) {
+        if (result.length === 1) {
+          return result[0];
+        }
+        throw errors.tooManyResults();
+      }
+      if (isNaN(result)) {
+        throw errors.executionFailed();
+      }
+      return result;
+    } catch (e) {
+      if (isDatatable(input) && input.rows.length === 0) {
+        throw errors.emptyDatatable();
+      } else {
+        throw e;
+      }
+    }
+  },
+};
diff --git a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/math.test.js b/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts
similarity index 89%
rename from x-pack/plugins/canvas/canvas_plugin_src/functions/common/math.test.js
rename to src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts
index f5b8123ab8568..5b0108720da03 100644
--- a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/math.test.js
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts
@@ -1,19 +1,16 @@
 /*
  * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
  * or more contributor license agreements. Licensed under the Elastic License
- * 2.0; you may not use this file except in compliance with the Elastic License
- * 2.0.
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
  */
 
-import { functionWrapper } from '../../../test_helpers/function_wrapper';
-import { getFunctionErrors } from '../../../i18n';
-import { emptyTable, testTable } from './__fixtures__/test_tables';
-import { math } from './math';
-
-const errors = getFunctionErrors().math;
+import { errors, math } from '../math';
+import { emptyTable, functionWrapper, testTable } from './utils';
 
 describe('math', () => {
-  const fn = functionWrapper(math);
+  const fn = functionWrapper<unknown>(math);
 
   it('evaluates math expressions without reference to context', () => {
     expect(fn(null, { expression: '10.5345' })).toBe(10.5345);
diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/utils.ts b/src/plugins/expressions/common/expression_functions/specs/tests/utils.ts
index 44ed87dc02360..7369570cf2c4b 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/utils.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/utils.ts
@@ -15,10 +15,12 @@ import { Datatable } from '../../../expression_types';
  * Takes a function spec and passes in default args,
  * overriding with any provided args.
  */
-export const functionWrapper = (spec: AnyExpressionFunctionDefinition) => {
+export const functionWrapper = <ContextType = object | null>(
+  spec: AnyExpressionFunctionDefinition
+) => {
   const defaultArgs = mapValues(spec.args, (argSpec) => argSpec.default);
   return (
-    context: object | null,
+    context: ContextType,
     args: Record<string, any> = {},
     handlers: ExecutionContext = {} as ExecutionContext
   ) => spec.fn(context, { ...defaultArgs, ...args }, handlers);
diff --git a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/index.ts b/x-pack/plugins/canvas/canvas_plugin_src/functions/common/index.ts
index a00718fce0797..5c4d1d55cff04 100644
--- a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/index.ts
+++ b/x-pack/plugins/canvas/canvas_plugin_src/functions/common/index.ts
@@ -34,7 +34,6 @@ import { joinRows } from './join_rows';
 import { lt } from './lt';
 import { lte } from './lte';
 import { mapCenter } from './map_center';
-import { math } from './math';
 import { metric } from './metric';
 import { neq } from './neq';
 import { ply } from './ply';
@@ -88,7 +87,6 @@ export const functions = [
   lte,
   joinRows,
   mapCenter,
-  math,
   metric,
   neq,
   ply,
diff --git a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/math.ts b/x-pack/plugins/canvas/canvas_plugin_src/functions/common/math.ts
deleted file mode 100644
index af70fa729b7da..0000000000000
--- a/x-pack/plugins/canvas/canvas_plugin_src/functions/common/math.ts
+++ /dev/null
@@ -1,70 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License
- * 2.0; you may not use this file except in compliance with the Elastic License
- * 2.0.
- */
-
-import { evaluate } from '@kbn/tinymath';
-import { pivotObjectArray } from '../../../common/lib/pivot_object_array';
-import { Datatable, isDatatable, ExpressionFunctionDefinition } from '../../../types';
-import { getFunctionHelp, getFunctionErrors } from '../../../i18n';
-
-interface Arguments {
-  expression: string;
-}
-
-type Input = number | Datatable;
-
-export function math(): ExpressionFunctionDefinition<'math', Input, Arguments, number> {
-  const { help, args: argHelp } = getFunctionHelp().math;
-  const errors = getFunctionErrors().math;
-
-  return {
-    name: 'math',
-    type: 'number',
-    inputTypes: ['number', 'datatable'],
-    help,
-    args: {
-      expression: {
-        aliases: ['_'],
-        types: ['string'],
-        help: argHelp.expression,
-      },
-    },
-    fn: (input, args) => {
-      const { expression } = args;
-
-      if (!expression || expression.trim() === '') {
-        throw errors.emptyExpression();
-      }
-
-      const mathContext = isDatatable(input)
-        ? pivotObjectArray(
-            input.rows,
-            input.columns.map((col) => col.name)
-          )
-        : { value: input };
-
-      try {
-        const result = evaluate(expression, mathContext);
-        if (Array.isArray(result)) {
-          if (result.length === 1) {
-            return result[0];
-          }
-          throw errors.tooManyResults();
-        }
-        if (isNaN(result)) {
-          throw errors.executionFailed();
-        }
-        return result;
-      } catch (e) {
-        if (isDatatable(input) && input.rows.length === 0) {
-          throw errors.emptyDatatable();
-        } else {
-          throw e;
-        }
-      }
-    },
-  };
-}
diff --git a/x-pack/plugins/canvas/i18n/functions/dict/math.ts b/x-pack/plugins/canvas/i18n/functions/dict/math.ts
deleted file mode 100644
index 110136872e1ff..0000000000000
--- a/x-pack/plugins/canvas/i18n/functions/dict/math.ts
+++ /dev/null
@@ -1,69 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License
- * 2.0; you may not use this file except in compliance with the Elastic License
- * 2.0.
- */
-
-import { i18n } from '@kbn/i18n';
-import { math } from '../../../canvas_plugin_src/functions/common/math';
-import { FunctionHelp } from '../function_help';
-import { FunctionFactory } from '../../../types';
-import { DATATABLE, CONTEXT, TINYMATH, TINYMATH_URL, TYPE_NUMBER } from '../../constants';
-
-export const help: FunctionHelp<FunctionFactory<typeof math>> = {
-  help: i18n.translate('xpack.canvas.functions.mathHelpText', {
-    defaultMessage:
-      'Interprets a {TINYMATH} math expression using a {TYPE_NUMBER} or {DATATABLE} as {CONTEXT}. ' +
-      'The {DATATABLE} columns are available by their column name. ' +
-      'If the {CONTEXT} is a number it is available as {value}.',
-    values: {
-      TINYMATH,
-      CONTEXT,
-      DATATABLE,
-      value: '`value`',
-      TYPE_NUMBER,
-    },
-  }),
-  args: {
-    expression: i18n.translate('xpack.canvas.functions.math.args.expressionHelpText', {
-      defaultMessage: 'An evaluated {TINYMATH} expression. See {TINYMATH_URL}.',
-      values: {
-        TINYMATH,
-        TINYMATH_URL,
-      },
-    }),
-  },
-};
-
-export const errors = {
-  emptyExpression: () =>
-    new Error(
-      i18n.translate('xpack.canvas.functions.math.emptyExpressionErrorMessage', {
-        defaultMessage: 'Empty expression',
-      })
-    ),
-  tooManyResults: () =>
-    new Error(
-      i18n.translate('xpack.canvas.functions.math.tooManyResultsErrorMessage', {
-        defaultMessage:
-          'Expressions must return a single number. Try wrapping your expression in {mean} or {sum}',
-        values: {
-          mean: 'mean()',
-          sum: 'sum()',
-        },
-      })
-    ),
-  executionFailed: () =>
-    new Error(
-      i18n.translate('xpack.canvas.functions.math.executionFailedErrorMessage', {
-        defaultMessage: 'Failed to execute math expression. Check your column names',
-      })
-    ),
-  emptyDatatable: () =>
-    new Error(
-      i18n.translate('xpack.canvas.functions.math.emptyDatatableErrorMessage', {
-        defaultMessage: 'Empty datatable',
-      })
-    ),
-};
diff --git a/x-pack/plugins/canvas/i18n/functions/function_errors.ts b/x-pack/plugins/canvas/i18n/functions/function_errors.ts
index ac86eb4c4d0e9..4a85018c1b4ac 100644
--- a/x-pack/plugins/canvas/i18n/functions/function_errors.ts
+++ b/x-pack/plugins/canvas/i18n/functions/function_errors.ts
@@ -16,7 +16,6 @@ import { errors as demodata } from './dict/demodata';
 import { errors as getCell } from './dict/get_cell';
 import { errors as image } from './dict/image';
 import { errors as joinRows } from './dict/join_rows';
-import { errors as math } from './dict/math';
 import { errors as ply } from './dict/ply';
 import { errors as pointseries } from './dict/pointseries';
 import { errors as progress } from './dict/progress';
@@ -36,7 +35,6 @@ export const getFunctionErrors = () => ({
   getCell,
   image,
   joinRows,
-  math,
   ply,
   pointseries,
   progress,
diff --git a/x-pack/plugins/canvas/i18n/functions/function_help.ts b/x-pack/plugins/canvas/i18n/functions/function_help.ts
index 87e6883e599ce..512ebc4ff8c93 100644
--- a/x-pack/plugins/canvas/i18n/functions/function_help.ts
+++ b/x-pack/plugins/canvas/i18n/functions/function_help.ts
@@ -47,7 +47,6 @@ import { help as lt } from './dict/lt';
 import { help as lte } from './dict/lte';
 import { help as mapCenter } from './dict/map_center';
 import { help as markdown } from './dict/markdown';
-import { help as math } from './dict/math';
 import { help as metric } from './dict/metric';
 import { help as neq } from './dict/neq';
 import { help as pie } from './dict/pie';
@@ -209,7 +208,6 @@ export const getFunctionHelp = (): FunctionHelpDict => ({
   lte,
   mapCenter,
   markdown,
-  math,
   metric,
   neq,
   pie,

From b89934fad93e2c9ce74a2e1f1905bf9d684ef4b5 Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Mon, 15 Feb 2021 17:26:43 +0100
Subject: [PATCH 04/14] :sparkles: Add new onError argument

---
 .../common/expression_functions/specs/math.ts | 37 ++++++++++++++++---
 .../specs/tests/math.test.ts                  | 20 ++++++++++
 2 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/src/plugins/expressions/common/expression_functions/specs/math.ts b/src/plugins/expressions/common/expression_functions/specs/math.ts
index f963902c4b32f..8f876f92eb072 100644
--- a/src/plugins/expressions/common/expression_functions/specs/math.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/math.ts
@@ -12,9 +12,10 @@ import { evaluate } from '@kbn/tinymath';
 import { ExpressionFunctionDefinition } from '../types';
 import { Datatable, isDatatable } from '../../expression_types';
 
-export interface MathArguments {
+export type MathArguments = {
   expression: string;
-}
+  onError?: 'null' | 'zero' | 'false' | 'throw';
+};
 
 export type MathInput = number | Datatable;
 
@@ -69,9 +70,20 @@ export const errors = {
     ),
 };
 
-export const math: ExpressionFunctionDefinition<'math', MathInput, MathArguments, number> = {
+const fallbackValue = {
+  null: null,
+  zero: 0,
+  false: false,
+} as const;
+
+export const math: ExpressionFunctionDefinition<
+  'math',
+  MathInput,
+  MathArguments,
+  boolean | number | null
+> = {
   name: 'math',
-  type: 'number',
+  type: undefined,
   inputTypes: ['number', 'datatable'],
   help: i18n.translate('expressions.functions.mathHelpText', {
     defaultMessage:
@@ -98,9 +110,20 @@ export const math: ExpressionFunctionDefinition<'math', MathInput, MathArguments
         },
       }),
     },
+    onError: {
+      types: ['string'],
+      help: i18n.translate('expressions.functions.math.args.onErrorHelpText', {
+        defaultMessage:
+          "In case the {TINYMATH} evaluation fails or returns NaN, the return value is specified by onError. If it's set to throw, it will throw an exception, terminating expression execution (default).",
+        values: {
+          TINYMATH,
+        },
+      }),
+    },
   },
   fn: (input, args) => {
-    const { expression } = args;
+    const { expression, onError } = args;
+    const onErrorValue = onError ?? 'throw';
 
     if (!expression || expression.trim() === '') {
       throw errors.emptyExpression();
@@ -122,6 +145,10 @@ export const math: ExpressionFunctionDefinition<'math', MathInput, MathArguments
         throw errors.tooManyResults();
       }
       if (isNaN(result)) {
+        // make TS happy
+        if (onErrorValue !== 'throw' && onErrorValue in fallbackValue) {
+          return fallbackValue[onErrorValue];
+        }
         throw errors.executionFailed();
       }
       return result;
diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts b/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts
index 5b0108720da03..ae5a2f1e6a008 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts
@@ -45,6 +45,14 @@ describe('math', () => {
         expect(fn(testTable, { expression: 'count(name)' })).toBe(9);
       });
     });
+
+    describe('onError', () => {
+      it('should return the desired fallback value, for invalid expressions', () => {
+        expect(fn(testTable, { expression: 'mean(name)', onError: 'zero' })).toBe(0);
+        expect(fn(testTable, { expression: 'mean(name)', onError: 'null' })).toBe(null);
+        expect(fn(testTable, { expression: 'mean(name)', onError: 'false' })).toBe(false);
+      });
+    });
   });
 
   describe('invalid expressions', () => {
@@ -85,5 +93,17 @@ describe('math', () => {
         new RegExp(errors.emptyDatatable().message)
       );
     });
+
+    it('should not throw when requesting fallback values for invalid expression', () => {
+      expect(() => fn(testTable, { expression: 'mean(name)', onError: 'zero' })).not.toThrow();
+      expect(() => fn(testTable, { expression: 'mean(name)', onError: 'false' })).not.toThrow();
+      expect(() => fn(testTable, { expression: 'mean(name)', onError: 'null' })).not.toThrow();
+    });
+
+    it('should throw when declared in the onError argument', () => {
+      expect(() => fn(testTable, { expression: 'mean(name)', onError: 'throw' })).toThrow(
+        new RegExp(errors.executionFailed().message)
+      );
+    });
   });
 });

From 4c8fd8c8d2c04c192915eeeb1cedb4504c63ab5b Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Mon, 15 Feb 2021 17:28:17 +0100
Subject: [PATCH 05/14] :globe_with_meridians: Fix i18n for math

---
 x-pack/plugins/translations/translations/ja-JP.json | 6 ------
 x-pack/plugins/translations/translations/zh-CN.json | 6 ------
 2 files changed, 12 deletions(-)

diff --git a/x-pack/plugins/translations/translations/ja-JP.json b/x-pack/plugins/translations/translations/ja-JP.json
index 32b2c4b3cdc04..dc79b22479d9d 100644
--- a/x-pack/plugins/translations/translations/ja-JP.json
+++ b/x-pack/plugins/translations/translations/ja-JP.json
@@ -5984,12 +5984,6 @@
     "xpack.canvas.functions.markdown.args.fontHelpText": "コンテンツの {CSS} フォントプロパティです。たとえば、{fontFamily} または {fontWeight} です。",
     "xpack.canvas.functions.markdown.args.openLinkHelpText": "新しいタブでリンクを開くためのtrue/false値。デフォルト値は「false」です。「true」に設定するとすべてのリンクが新しいタブで開くようになります。",
     "xpack.canvas.functions.markdownHelpText": "{MARKDOWN} テキストをレンダリングするエレメントを追加します。ヒント：単一の数字、メトリック、テキストの段落には {markdownFn} 関数を使います。",
-    "xpack.canvas.functions.math.args.expressionHelpText": "評価された {TINYMATH} 表現です。{TINYMATH_URL} をご覧ください。",
-    "xpack.canvas.functions.math.emptyDatatableErrorMessage": "空のデータベース",
-    "xpack.canvas.functions.math.emptyExpressionErrorMessage": "空の表現",
-    "xpack.canvas.functions.math.executionFailedErrorMessage": "数式の実行に失敗しました。列名を確認してください",
-    "xpack.canvas.functions.math.tooManyResultsErrorMessage": "式は 1 つの数字を返す必要があります。表現を {mean} または {sum} で囲んでみてください",
-    "xpack.canvas.functions.mathHelpText": "{TYPE_NUMBER}または{DATATABLE}を{CONTEXT}として使用して、{TINYMATH}数式を解釈します。{DATATABLE}列は列名で表示されます。{CONTEXT}が数字の場合は、{value}と表示されます。",
     "xpack.canvas.functions.metric.args.labelFontHelpText": "ラベルの {CSS} フォントプロパティです。例: {FONT_FAMILY} または {FONT_WEIGHT}。",
     "xpack.canvas.functions.metric.args.labelHelpText": "メトリックを説明するテキストです。",
     "xpack.canvas.functions.metric.args.metricFontHelpText": "メトリックの {CSS} フォントプロパティです。例: {FONT_FAMILY} または {FONT_WEIGHT}。",
diff --git a/x-pack/plugins/translations/translations/zh-CN.json b/x-pack/plugins/translations/translations/zh-CN.json
index d9a1476d3fd02..278fb49c4ceb5 100644
--- a/x-pack/plugins/translations/translations/zh-CN.json
+++ b/x-pack/plugins/translations/translations/zh-CN.json
@@ -5995,12 +5995,6 @@
     "xpack.canvas.functions.markdown.args.fontHelpText": "内容的 {CSS} 字体属性。例如 {fontFamily} 或 {fontWeight}。",
     "xpack.canvas.functions.markdown.args.openLinkHelpText": "用于在新标签页中打开链接的 true 或 false 值。默认值为 `false`。设置为 `true` 时将在新标签页中打开所有链接。",
     "xpack.canvas.functions.markdownHelpText": "添加呈现 {MARKDOWN} 文本的元素。提示：将 {markdownFn} 函数用于单个数字、指标和文本段落。",
-    "xpack.canvas.functions.math.args.expressionHelpText": "已计算的 {TINYMATH} 表达式。请参阅 {TINYMATH_URL}。",
-    "xpack.canvas.functions.math.emptyDatatableErrorMessage": "空数据表",
-    "xpack.canvas.functions.math.emptyExpressionErrorMessage": "空表达式",
-    "xpack.canvas.functions.math.executionFailedErrorMessage": "无法执行数学表达式。检查您的列名称",
-    "xpack.canvas.functions.math.tooManyResultsErrorMessage": "表达式必须返回单个数字。尝试将您的表达式包装在 {mean} 或 {sum} 中",
-    "xpack.canvas.functions.mathHelpText": "使用 {TYPE_NUMBER} 或 {DATATABLE} 作为 {CONTEXT} 来解释 {TINYMATH} 数学表达式。{DATATABLE} 列按列名使用。如果 {CONTEXT} 是数字，则作为 {value} 使用。",
     "xpack.canvas.functions.metric.args.labelFontHelpText": "标签的 {CSS} 字体属性。例如 {FONT_FAMILY} 或 {FONT_WEIGHT}。",
     "xpack.canvas.functions.metric.args.labelHelpText": "描述指标的文本。",
     "xpack.canvas.functions.metric.args.metricFontHelpText": "指标的 {CSS} 字体属性。例如 {FONT_FAMILY} 或 {FONT_WEIGHT}。",

From 75fecc8195e705244817d6867ec74d6ad710e89b Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Tue, 16 Feb 2021 10:39:30 +0100
Subject: [PATCH 06/14] :memo: Update expressions doc with new args

---
 .../canvas/canvas-function-reference.asciidoc | 19 ++++++++++++++++++-
 .../expression_functions/specs/map_column.ts  |  2 +-
 .../common/expression_functions/specs/math.ts |  2 +-
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/docs/canvas/canvas-function-reference.asciidoc b/docs/canvas/canvas-function-reference.asciidoc
index 6a6c840074f02..eaaf68eb06195 100644
--- a/docs/canvas/canvas-function-reference.asciidoc
+++ b/docs/canvas/canvas-function-reference.asciidoc
@@ -1697,6 +1697,16 @@ Aliases: `column`, `name`
 Aliases: `exp`, `fn`, `function`
 |`boolean`, `number`, `string`, `null`
 |A Canvas expression that is passed to each row as a single row `datatable`.
+
+|`id`
+
+|`string`, `null`
+|An optional id of the resulting column. When not specified or `null` the name argument is used as id.
+
+|`copyMetaFrom`
+
+|`string`, `null`
+|If set, the meta object from the specified column id is copied over to the specified target column. Throws an exception if the column doesn't exist
 |===
 
 *Returns:* `datatable`
@@ -1755,9 +1765,16 @@ Interprets a `TinyMath` math expression using a `number` or `datatable` as _cont
 Alias: `expression`
 |`string`
 |An evaluated `TinyMath` expression. See https://www.elastic.co/guide/en/kibana/current/canvas-tinymath-functions.html.
+
+|`onError` 
+
+|`string`
+|In case the `TinyMath` evaluation fails or returns NaN, the return value is specified by onError. For example, `"null"`, `"zero"`, `"false"`, `"throw"`. When `"throw"`, it will throw an exception, terminating expression execution.
+
+Default: `"throw"`
 |===
 
-*Returns:* `number`
+*Returns:* `number` | `boolean` | `null`
 
 
 [float]
diff --git a/src/plugins/expressions/common/expression_functions/specs/map_column.ts b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
index a77bed99f9492..6c11b2d2df08d 100644
--- a/src/plugins/expressions/common/expression_functions/specs/map_column.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
@@ -73,7 +73,7 @@ export const mapColumn: ExpressionFunctionDefinition<
       types: ['string', 'null'],
       help: i18n.translate('expressions.functions.mapColumn.args.copyMetaFromHelpText', {
         defaultMessage:
-          "if set, the meta object from the specified column id is copied over to the specified target column. Throws an exception of the column doesn't exist",
+          "If set, the meta object from the specified column id is copied over to the specified target column. Throws an exception if the column doesn't exist",
       }),
       required: false,
       default: null,
diff --git a/src/plugins/expressions/common/expression_functions/specs/math.ts b/src/plugins/expressions/common/expression_functions/specs/math.ts
index 8f876f92eb072..764ef0cc80ff6 100644
--- a/src/plugins/expressions/common/expression_functions/specs/math.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/math.ts
@@ -114,7 +114,7 @@ export const math: ExpressionFunctionDefinition<
       types: ['string'],
       help: i18n.translate('expressions.functions.math.args.onErrorHelpText', {
         defaultMessage:
-          "In case the {TINYMATH} evaluation fails or returns NaN, the return value is specified by onError. If it's set to throw, it will throw an exception, terminating expression execution (default).",
+          "In case the {TINYMATH} evaluation fails or returns NaN, the return value is specified by onError. When `'throw'`, it will throw an exception, terminating expression execution (default).",
         values: {
           TINYMATH,
         },

From 7eb7ebd5b71629ac80741661380ebc233d9f5086 Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Thu, 18 Feb 2021 15:23:21 +0100
Subject: [PATCH 07/14] :sparkles: Add the divide by zero handling

---
 .../common/expression_functions/specs/math.ts         |  3 +++
 .../expression_functions/specs/tests/math.test.ts     | 11 +++++++++++
 2 files changed, 14 insertions(+)

diff --git a/src/plugins/expressions/common/expression_functions/specs/math.ts b/src/plugins/expressions/common/expression_functions/specs/math.ts
index 764ef0cc80ff6..c14b4ed5b7e4b 100644
--- a/src/plugins/expressions/common/expression_functions/specs/math.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/math.ts
@@ -153,6 +153,9 @@ export const math: ExpressionFunctionDefinition<
       }
       return result;
     } catch (e) {
+      if (onErrorValue !== 'throw' && onErrorValue in fallbackValue) {
+        return fallbackValue[onErrorValue];
+      }
       if (isDatatable(input) && input.rows.length === 0) {
         throw errors.emptyDatatable();
       } else {
diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts b/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts
index ae5a2f1e6a008..7541852cdbdaf 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/math.test.ts
@@ -52,6 +52,11 @@ describe('math', () => {
         expect(fn(testTable, { expression: 'mean(name)', onError: 'null' })).toBe(null);
         expect(fn(testTable, { expression: 'mean(name)', onError: 'false' })).toBe(false);
       });
+      it('should return the desired fallback value, for division by zero', () => {
+        expect(fn(testTable, { expression: '1/0', onError: 'zero' })).toBe(0);
+        expect(fn(testTable, { expression: '1/0', onError: 'null' })).toBe(null);
+        expect(fn(testTable, { expression: '1/0', onError: 'false' })).toBe(false);
+      });
     });
   });
 
@@ -105,5 +110,11 @@ describe('math', () => {
         new RegExp(errors.executionFailed().message)
       );
     });
+
+    it('should throw when dividing by zero', () => {
+      expect(() => fn(testTable, { expression: '1/0', onError: 'throw' })).toThrow(
+        new RegExp('Cannot divide by 0')
+      );
+    });
   });
 });

From 804507a8c8c2d8f050213b73dd4034f1faf31fae Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Thu, 18 Feb 2021 17:52:57 +0100
Subject: [PATCH 08/14] :sparkles: Add options for autocomplete

---
 .../expressions/common/expression_functions/specs/math.ts        | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/plugins/expressions/common/expression_functions/specs/math.ts b/src/plugins/expressions/common/expression_functions/specs/math.ts
index c14b4ed5b7e4b..a70c032769b57 100644
--- a/src/plugins/expressions/common/expression_functions/specs/math.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/math.ts
@@ -112,6 +112,7 @@ export const math: ExpressionFunctionDefinition<
     },
     onError: {
       types: ['string'],
+      options: ['throw', 'false', 'zero', 'null'],
       help: i18n.translate('expressions.functions.math.args.onErrorHelpText', {
         defaultMessage:
           "In case the {TINYMATH} evaluation fails or returns NaN, the return value is specified by onError. When `'throw'`, it will throw an exception, terminating expression execution (default).",

From 0ac1f27f9a26f0aa5a7a9170b93256b4c422121e Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Mon, 22 Feb 2021 12:55:01 +0100
Subject: [PATCH 09/14] :bug: Fix bug wth type picker

---
 .../expressions/common/expression_functions/specs/map_column.ts | 2 +-
 .../common/expression_functions/specs/tests/map_column.test.ts  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/plugins/expressions/common/expression_functions/specs/map_column.ts b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
index 6c11b2d2df08d..95e953fd6c528 100644
--- a/src/plugins/expressions/common/expression_functions/specs/map_column.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
@@ -97,7 +97,7 @@ export const mapColumn: ExpressionFunctionDefinition<
 
     return Promise.all(rowPromises).then((rows) => {
       const existingColumnIndex = columns.findIndex(({ name }) => name === args.name);
-      const type = rows.length ? getType(rows[0][args.name]) : 'null';
+      const type = rows.length ? getType(rows[0][columnId]) : 'null';
       const newColumn = {
         id: columnId,
         name: args.name,
diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
index 588d1f34590f3..f83a22022066d 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
@@ -77,7 +77,7 @@ describe('mapColumn', () => {
         expect(result.columns[nameColumnIndex]).toEqual({
           id: 'myid',
           name: 'name',
-          meta: { type: 'string' },
+          meta: { type: 'number' },
         });
       }
     );

From a5c8bdfe02591232e8451274376feae116e51697 Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Tue, 23 Feb 2021 18:20:50 +0100
Subject: [PATCH 10/14] :ok_hand: Integrated feedback

---
 .../expression_functions/specs/map_column.ts  |  6 ++--
 .../specs/tests/map_column.test.ts            | 35 +++++++++++++------
 2 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/src/plugins/expressions/common/expression_functions/specs/map_column.ts b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
index 95e953fd6c528..ad54ce4a754e1 100644
--- a/src/plugins/expressions/common/expression_functions/specs/map_column.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
@@ -61,7 +61,7 @@ export const mapColumn: ExpressionFunctionDefinition<
       aliases: ['exp', 'fn', 'function'],
       help: i18n.translate('expressions.functions.mapColumn.args.expressionHelpText', {
         defaultMessage:
-          'A {CANVAS} expression that is passed to each row as a single row {DATATABLE}.',
+          'An expression that is executed on every row, provided with a single-row {DATATABLE} context and returning the cell value.',
         values: {
           CANVAS: 'canvas',
           DATATABLE: '`datatable`',
@@ -73,7 +73,7 @@ export const mapColumn: ExpressionFunctionDefinition<
       types: ['string', 'null'],
       help: i18n.translate('expressions.functions.mapColumn.args.copyMetaFromHelpText', {
         defaultMessage:
-          "If set, the meta object from the specified column id is copied over to the specified target column. Throws an exception if the column doesn't exist",
+          "If set, the meta object from the specified column id is copied over to the specified target column. If the column doesn't exist it silently fails.",
       }),
       required: false,
       default: null,
@@ -104,7 +104,7 @@ export const mapColumn: ExpressionFunctionDefinition<
         meta: { type },
       };
       if (args.copyMetaFrom) {
-        const metaSourceFrom = columns.find(({ name }) => name === args.copyMetaFrom);
+        const metaSourceFrom = columns.find(({ id }) => id === args.copyMetaFrom);
         newColumn.meta = { ...newColumn.meta, ...(metaSourceFrom?.meta || {}) };
       }
 
diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
index f83a22022066d..284374dbefbf3 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
@@ -84,17 +84,30 @@ describe('mapColumn', () => {
   });
 
   it('should copy over the meta information from the specified column', () => {
-    return runFn(testTable, { name: 'name', copyMetaFrom: 'time', expression: pricePlusTwo }).then(
-      (result) => {
-        const nameColumnIndex = result.columns.findIndex(({ name }) => name === 'name');
-        expect(result.type).toBe('datatable');
-        expect(result.columns[nameColumnIndex]).toEqual({
-          id: 'name',
-          name: 'name',
-          meta: { type: 'date' },
-        });
-      }
-    );
+    return runFn(
+      {
+        ...testTable,
+        columns: [
+          ...testTable.columns,
+          // add a new entry
+          {
+            id: 'myId',
+            name: 'myName',
+            meta: { type: 'date' },
+          },
+        ],
+        rows: testTable.rows.map((row) => ({ ...row, myId: Date.now() })),
+      },
+      { name: 'name', copyMetaFrom: 'myId', expression: pricePlusTwo }
+    ).then((result) => {
+      const nameColumnIndex = result.columns.findIndex(({ name }) => name === 'name');
+      expect(result.type).toBe('datatable');
+      expect(result.columns[nameColumnIndex]).toEqual({
+        id: 'name',
+        name: 'name',
+        meta: { type: 'date' },
+      });
+    });
   });
 
   it('should be resilient if the references column for meta information does not exists', () => {

From 6bfa8230c618774ff1f9d0b4e88aba759342d9c0 Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Tue, 23 Feb 2021 19:22:23 +0100
Subject: [PATCH 11/14] :bug: Fix unused value

---
 .../expressions/common/expression_functions/specs/map_column.ts  | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/plugins/expressions/common/expression_functions/specs/map_column.ts b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
index ad54ce4a754e1..e2605e5ddf38d 100644
--- a/src/plugins/expressions/common/expression_functions/specs/map_column.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/map_column.ts
@@ -63,7 +63,6 @@ export const mapColumn: ExpressionFunctionDefinition<
         defaultMessage:
           'An expression that is executed on every row, provided with a single-row {DATATABLE} context and returning the cell value.',
         values: {
-          CANVAS: 'canvas',
           DATATABLE: '`datatable`',
         },
       }),

From a6cb2d0c8d58485eccb129ba46c2a6be54e7340c Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Wed, 24 Feb 2021 10:06:29 +0100
Subject: [PATCH 12/14] :white_check_mark: Add more tests

---
 .../specs/tests/map_column.test.ts              | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
index 284374dbefbf3..08cbb74603836 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
@@ -93,7 +93,7 @@ describe('mapColumn', () => {
           {
             id: 'myId',
             name: 'myName',
-            meta: { type: 'date' },
+            meta: { type: 'date', params: { type: 'date', digits: 2 } },
           },
         ],
         rows: testTable.rows.map((row) => ({ ...row, myId: Date.now() })),
@@ -105,7 +105,7 @@ describe('mapColumn', () => {
       expect(result.columns[nameColumnIndex]).toEqual({
         id: 'name',
         name: 'name',
-        meta: { type: 'date' },
+        meta: { type: 'date', params: { type: 'date', digits: 2 } },
       });
     });
   });
@@ -122,6 +122,19 @@ describe('mapColumn', () => {
     );
   });
 
+  it('should correctly infer the type fromt he first row if the references column for meta information does not exists', () => {
+    return runFn(
+      { ...emptyTable, rows: [...emptyTable.rows, { value: 5 }] },
+      { name: 'value', copyMetaFrom: 'time', expression: pricePlusTwo }
+    ).then((result) => {
+      expect(result.type).toBe('datatable');
+      expect(result.columns).toHaveLength(1);
+      expect(result.columns[0]).toHaveProperty('name', 'value');
+      expect(result.columns[0]).toHaveProperty('id', 'value');
+      expect(result.columns[0].meta).toHaveProperty('type', 'number');
+    });
+  });
+
   describe('expression', () => {
     it('maps null values to the new column', () => {
       return runFn(testTable, { name: 'empty' }).then((result) => {

From 7cdf96f1434188e5f564348206eae8b7718958f3 Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Wed, 24 Feb 2021 11:52:40 +0100
Subject: [PATCH 13/14] :bug: Fix type issue

---
 .../common/expression_functions/specs/tests/map_column.test.ts  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
index 08cbb74603836..3432e2313495f 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
@@ -93,7 +93,7 @@ describe('mapColumn', () => {
           {
             id: 'myId',
             name: 'myName',
-            meta: { type: 'date', params: { type: 'date', digits: 2 } },
+            meta: { type: 'date', params: { id: 'number', params: { digits: 2 } } },
           },
         ],
         rows: testTable.rows.map((row) => ({ ...row, myId: Date.now() })),

From 0f601c013da33772430f9bb41eba1fbd2590ccd5 Mon Sep 17 00:00:00 2001
From: dej611 <dej611@gmail.com>
Date: Wed, 24 Feb 2021 15:13:19 +0100
Subject: [PATCH 14/14] :white_check_mark: Fix unit test

---
 .../common/expression_functions/specs/tests/map_column.test.ts  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
index 3432e2313495f..6b0dce4ff9a2a 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/map_column.test.ts
@@ -105,7 +105,7 @@ describe('mapColumn', () => {
       expect(result.columns[nameColumnIndex]).toEqual({
         id: 'name',
         name: 'name',
-        meta: { type: 'date', params: { type: 'date', digits: 2 } },
+        meta: { type: 'date', params: { id: 'number', params: { digits: 2 } } },
       });
     });
   });