feat: fieldConfig validation moved from astToSchema() to directoryToAst() method.

BREAKING CHANGE: FieldConfig is now stored in AST.fieldConfig property and is used as mutable value (every ast transformer use this value and may change it).

Author: nodkz

src/VisitInfo.ts

@@ -133,9 +133,10 @@ export class VisitInfo<TNode extends AstDirNode | AstFileNode | AstRootTypeNode,
   get fieldConfig(): FieldConfig {
     const node = this.node;
     if (node.kind === 'file') {
-      return node.code?.default as FieldConfig;
+      return node.fieldConfig;
     } else if (node.kind === 'dir' || this.node.kind === 'rootType') {
-      return node.namespaceConfig?.code?.default as FieldConfig;
+      // TODO: think about namespaceConfig (how to do it not null)
+      return node.namespaceConfig?.fieldConfig as any;
     }
     throw new Error(`Cannot get fieldConfig. Node has some strange kind: ${node.kind}`);
   }

src/__tests__/VisitInfo-test.ts

@@ -15,12 +15,11 @@ const nodeParent = {
 } as AstRootNode;
 const node = {
   absPath: 'schema/query/some_endpoint.ts',
-  code: {
-    default: {
-      type: 'String',
-      resolve: () => 'Hello!',
-    },
-  },
+  code: {},
+  fieldConfig: {
+    type: 'String',
+    resolve: () => 'Hello!',
+  } as any,
   kind: 'file',
   name: 'some_endpoint',
 } as AstFileNode;
@@ -121,7 +120,7 @@ describe('VisitInfo', () => {
       operation: 'query',
       fieldName: 'ping',
       fieldPath: ['query.storage', 'viewer', 'utils.debug'],
-      node,
+      node: { ...node, fieldConfig: { ...node.fieldConfig } },
       nodeParent,
       schemaComposer,
     });

src/__tests__/__snapshots__/directoryToAst-test.ts.snap

@@ -93,6 +93,7 @@ Object {
       "namespaceConfig": Object {
         "absPath": Any<String>,
         "code": Any<Object>,
+        "fieldConfig": Any<Object>,
         "kind": "file",
         "name": "index",
       },

src/__tests__/directoryToAst-test.ts

@@ -37,6 +37,7 @@ describe('directoryToAst()', () => {
               name: 'index',
               absPath: expect.any(String),
               code: expect.any(Object),
+              fieldConfig: expect.any(Object),
             },
           },
           'some.nested': expect.objectContaining({ kind: 'file' }),

src/astToSchema.ts

@@ -5,15 +5,11 @@ import {
   ObjectTypeComposerFieldConfig,
   isOutputTypeDefinitionString,
   isWrappedTypeNameString,
-  isComposeOutputType,
-  isSomeOutputTypeDefinitionString,
   inspect,
-  isFunction,
 } from 'graphql-compose';
 import { AstRootNode, AstRootTypeNode, AstDirNode, AstFileNode } from './directoryToAst';
 import dedent from 'dedent';
 import { GraphQLObjectType } from 'graphql';
-import { FieldConfig, NamespaceConfig } from './typeDefs';
 
 export interface AstToSchemaOptions {
   /**
@@ -109,7 +105,7 @@ export function createFields(
 
   if (ast.kind === 'file') {
     parent.addNestedFields({
-      [name]: prepareFieldConfig(ast) as FieldConfig,
+      [name]: ast.fieldConfig,
     });
     return;
   }
@@ -171,18 +167,7 @@ function prepareNamespaceFieldConfig(
   ast: AstFileNode,
   typename: string
 ): ObjectTypeComposerFieldConfig<any, any> {
-  if (!ast.code.default) {
-    throw new Error(dedent`
-      NamespaceModule MUST return FieldConfig as default export in '${ast.absPath}'. 
-      Eg:
-        export default {
-          type: 'SomeObjectTypeName',
-          resolve: () => ({}),
-        };
-    `);
-  }
-
-  const fc: any = ast.code.default;
+  const fc = ast.fieldConfig as any;
 
   if (!fc.type) {
     fc.type = sc.createObjectTC(typename);
@@ -218,46 +203,3 @@ function prepareNamespaceFieldConfig(
 
   return fc;
 }
-
-function prepareFieldConfig(ast: AstFileNode): FieldConfig | NamespaceConfig {
-  const fc = ast.code.default;
-
-  if (!fc) {
-    throw new Error(dedent`
-      Module MUST return FieldConfig as default export in '${ast.absPath}'. 
-      Eg:
-        export default {
-          type: 'String',
-          resolve: () => Date.now(),
-        };
-    `);
-  }
-
-  if (!fc.type || !isSomeOutputTypeDefinition(fc.type)) {
-    throw new Error(dedent`
-      Module MUST return FieldConfig with correct 'type: xxx' property in '${ast.absPath}'. 
-      Eg:
-        export default {
-          type: 'String'
-        };
-    `);
-  }
-
-  return fc;
-}
-
-function isSomeOutputTypeDefinition(type: any): boolean {
-  if (typeof type === 'string') {
-    // type: 'String'
-    return isSomeOutputTypeDefinitionString(type) || isWrappedTypeNameString(type);
-  } else if (Array.isArray(type)) {
-    // type: ['String']
-    return isSomeOutputTypeDefinition(type[0]);
-  } else if (isFunction(type)) {
-    // pass thunked type without internal checks
-    return true;
-  } else {
-    // type: 'type User { name: String }'
-    return isComposeOutputType(type);
-  }
-}

src/directoryToAst.ts

@@ -1,4 +1,12 @@
 import fs from 'fs';
+import {
+  dedent,
+  isComposeOutputType,
+  isFunction,
+  isSomeOutputTypeDefinitionString,
+  isWrappedTypeNameString,
+  Resolver,
+} from 'graphql-compose';
 import { join, resolve, dirname, basename } from 'path';
 import { FieldConfig, NamespaceConfig } from './typeDefs';
 
@@ -31,6 +39,12 @@ export interface AstFileNode extends AstBaseNode {
   code: {
     default?: FieldConfig | NamespaceConfig;
   };
+  /**
+   * This FieldConfig loaded from `code` and validated.
+   * This property is used by ast transformers and stores the last version of modified config.
+   * This value will be used by astToSchema method.
+   */
+  fieldConfig: FieldConfig;
 }
 
 export type RootTypeNames = 'query' | 'mutation' | 'subscription';
@@ -195,11 +209,16 @@ export function getAstForFile(
   if (absPath !== m.filename && checkInclusion(absPath, 'file', filename, options)) {
     // module name shouldn't include file extension
     const moduleName = filename.substring(0, filename.lastIndexOf('.'));
+    // namespace configs may not have `type` property
+    const checkType = moduleName !== 'index';
+    const code = m.require(absPath);
+    const fieldConfig = prepareFieldConfig(code, absPath, checkType);
     return {
       kind: 'file',
       name: moduleName,
       absPath,
-      code: m.require(absPath),
+      code,
+      fieldConfig,
     };
   }
 }
@@ -258,3 +277,62 @@ function checkInclusion(
 
   return true;
 }
+
+function prepareFieldConfig(code: any, absPath: string, checkType = true): FieldConfig {
+  const _fc = code?.default;
+  if (!_fc || typeof _fc !== 'object') {
+    throw new Error(dedent`
+      GraphQL entrypoint MUST return FieldConfig as default export in '${absPath}'. 
+      Eg:
+        export default {
+          type: 'String',
+          resolve: () => Date.now(),
+        };
+    `);
+  }
+
+  let fc: FieldConfig;
+  if (code.default instanceof Resolver) {
+    fc = (code.default as Resolver).getFieldConfig() as any;
+  } else {
+    // recreate object for immutability purposes (do not change object in module definition)
+    // NB. I don't know should we here recreate (args, extensions) but let's keep them as is for now.
+    fc = { ...code.default };
+  }
+
+  if (checkType) {
+    if (!fc.type || !isSomeOutputTypeDefinition(fc.type)) {
+      throw new Error(dedent`
+      Module MUST return FieldConfig with correct 'type: xxx' property in '${absPath}'. 
+      Eg:
+        export default {
+          type: 'String'
+        };
+    `);
+    }
+  }
+
+  if (fc.resolve && typeof fc.resolve !== 'function') {
+    throw new Error(
+      `Cannot load entrypoint config from ${absPath}. 'resolve' property must be a function or undefined.`
+    );
+  }
+
+  return fc;
+}
+
+function isSomeOutputTypeDefinition(type: any): boolean {
+  if (typeof type === 'string') {
+    // type: 'String'
+    return isSomeOutputTypeDefinitionString(type) || isWrappedTypeNameString(type);
+  } else if (Array.isArray(type)) {
+    // type: ['String']
+    return isSomeOutputTypeDefinition(type[0]);
+  } else if (isFunction(type)) {
+    // pass thunked type without internal checks
+    return true;
+  } else {
+    // type: 'type User { name: String }'
+    return isComposeOutputType(type);
+  }
+}

src/testHelpers.ts

@@ -52,7 +52,7 @@ function _getArgsForQuery(
   varNames.forEach((varName) => {
     if (!argNames.includes(varName)) {
       throw new Error(
-        `FieldConfig does not have '${varName}' argument. Avaliable arguments: '${argNames.join(
+        `FieldConfig does not have '${varName}' argument. Available arguments: '${argNames.join(
           "', '"
         )}'.`
       );