[#34] Added key delimiter

Author: ryu1kn

src/lib/csv-stringifier-factory.ts

@@ -14,6 +14,7 @@ export interface ObjectCsvStringifierParams {
     header: ObjectStringifierHeader;
     fieldDelimiter?: string;
     recordDelimiter?: string;
+    keyDelimiter?: string;
     alwaysQuote?: boolean;
 }
 
@@ -26,7 +27,7 @@ export class CsvStringifierFactory {
 
     createObjectCsvStringifier(params: ObjectCsvStringifierParams) {
         const fieldStringifier = createFieldStringifier(params.fieldDelimiter, params.alwaysQuote);
-        return new ObjectCsvStringifier(fieldStringifier, params.header, params.recordDelimiter);
+        return new ObjectCsvStringifier(fieldStringifier, params.header, params.recordDelimiter, params.keyDelimiter);
     }
 
 }

src/lib/csv-stringifiers/abstract.ts

@@ -18,23 +18,27 @@ export abstract class CsvStringifier<T> {
 
     getHeaderString(): string | null {
         const headerRecord = this.getHeaderRecord();
-        return headerRecord ? this.stringifyRecords([headerRecord]) : null;
+        return headerRecord ? this.joinRecords([this.getCsvLine(headerRecord)]) : null;
     }
 
     stringifyRecords(records: IterableIterator<T> | T[]): string {
         const csvLines = Array.from(records, record => this.getCsvLine(this.getRecordAsArray(record)));
-        return csvLines.join(this.recordDelimiter) + this.recordDelimiter;
+        return this.joinRecords(csvLines);
     }
 
     protected abstract getRecordAsArray(_record: T): Field[];
 
-    protected abstract getHeaderRecord(): T | null | undefined;
+    protected abstract getHeaderRecord(): string[] | null | undefined;
 
     private getCsvLine(record: Field[]): string {
         return record
             .map(fieldValue => this.fieldStringifier.stringify(fieldValue))
             .join(this.fieldDelimiter);
     }
+
+    private joinRecords(records: string[]) {
+        return records.join(this.recordDelimiter) + this.recordDelimiter;
+    }
 }
 
 function _validateRecordDelimiter(delimiter: string): void {

src/lib/csv-stringifiers/object.ts

@@ -4,22 +4,26 @@ import {Field, ObjectHeaderItem, ObjectStringifierHeader} from '../record';
 import {isObject, ObjectMap} from '../lang/object';
 
 export class ObjectCsvStringifier extends CsvStringifier<ObjectMap<Field>> {
-    private readonly header: ObjectStringifierHeader;
 
-    constructor(fieldStringifier: FieldStringifier, header: ObjectStringifierHeader, recordDelimiter?: string) {
+    constructor(fieldStringifier: FieldStringifier,
+                private readonly header: ObjectStringifierHeader,
+                recordDelimiter?: string,
+                private readonly keyDelimiter?: string) {
         super(fieldStringifier, recordDelimiter);
-        this.header = header;
     }
 
-    protected getHeaderRecord(): ObjectMap<Field> | null {
+    protected getHeaderRecord(): string[] | null {
         if (!this.isObjectHeader) return null;
-
-        return (this.header as ObjectHeaderItem[]).reduce((memo, field) =>
-            Object.assign({}, memo, {[field.id]: field.title}), {});
+        return (this.header as ObjectHeaderItem[]).map(field => field.title);
     }
 
     protected getRecordAsArray(record: ObjectMap<Field>): Field[] {
-        return this.fieldIds.map(field => record[field]);
+        return this.fieldIds.map(fieldId => this.getNestedValue(record, fieldId));
+    }
+
+    private getNestedValue(obj: ObjectMap<Field>, key: string) {
+        if (!this.keyDelimiter) return obj[key];
+        return key.split(this.keyDelimiter).reduce((subObj, keyPart) => subObj[keyPart], obj);
     }
 
     private get fieldIds(): string[] {

src/lib/csv-writer-factory.ts

@@ -17,6 +17,7 @@ export interface ObjectCsvWriterParams {
     header: ObjectStringifierHeader;
     fieldDelimiter?: string;
     recordDelimiter?: string;
+    keyDelimiter?: string;
     alwaysQuote?: boolean;
     encoding?: string;
     append?: boolean;
@@ -44,6 +45,7 @@ export class CsvWriterFactory {
             header: params.header,
             fieldDelimiter: params.fieldDelimiter,
             recordDelimiter: params.recordDelimiter,
+            keyDelimiter: params.keyDelimiter,
             alwaysQuote: params.alwaysQuote
         });
         return new CsvWriter(csvStringifier, params.path, params.encoding, params.append);

src/test/write-object-records.test.ts

@@ -8,13 +8,13 @@ describe('Write object records into CSV', () => {
 
     const makeFilePath = (id: string) => testFilePath(`object-${id}`);
     const records = [
-        {name: 'Bob', lang: 'French'},
-        {name: 'Mary', lang: 'English'}
+        {name: 'Bob', lang: 'French', address: {country: 'France'}},
+        {name: 'Mary', lang: 'English', address: {country: 'Australia'}}
     ];
 
     describe('When only path and header ids are given', () => {
         const filePath = makeFilePath('minimum');
-        let writer: CsvWriter<ObjectMap<string>>;
+        let writer: CsvWriter<ObjectMap<string|ObjectMap<string>>>;
 
         beforeEach(() => {
             writer = createObjectCsvWriter({
@@ -50,7 +50,7 @@ describe('Write object records into CSV', () => {
 
     describe('When field header is given with titles', () => {
         const filePath = makeFilePath('header');
-        let writer: CsvWriter<ObjectMap<string>>;
+        let writer: CsvWriter<ObjectMap<string|ObjectMap<string>>>;
 
         beforeEach(() => {
             writer = createObjectCsvWriter({
@@ -141,4 +141,18 @@ describe('Write object records into CSV', () => {
             assertFile(filePath, '"NAME","LANGUAGE"\n"Bob","French"\n"Mary","English"\n');
         });
     });
+
+    describe('When `keyDelimiter` flag is set', () => {
+        const filePath = makeFilePath('nested');
+        const writer = createObjectCsvWriter({
+            path: filePath,
+            header: [{id: 'name', title: 'NAME'}, {id: 'address.country', title: 'COUNTRY'}],
+            keyDelimiter: '.'
+        });
+
+        it('breaks keys into key paths', async () => {
+            await writer.writeRecords(records);
+            assertFile(filePath, 'NAME,COUNTRY\nBob,France\nMary,Australia\n');
+        });
+    });
 });