(feat) add argument --null-as-default-value to use null as default value for extracted translations

README.md

@@ -105,3 +105,7 @@ Options:
                                                       [boolean] [default: false]
   --key-as-default-value, -k   Use key as default value for translations
                                                       [boolean] [default: false]
+  --null-as-default-value, -n  Use null as default value for translations
+                                                      [boolean] [default: false]
+
+Arguments key-as-default-value and null-as-default-value are mutually exclusive

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@biesbjerg/ngx-translate-extract",
-  "version": "4.0.0",
+  "version": "4.1.0",
   "description": "Extract strings from projects using ngx-translate",
   "main": "dist/index.js",
   "typings": "dist/index.d.ts",

src/cli/cli.ts

@@ -10,6 +10,7 @@ import { MarkerParser } from '../parsers/marker.parser';
 import { PostProcessorInterface } from '../post-processors/post-processor.interface';
 import { SortByKeyPostProcessor } from '../post-processors/sort-by-key.post-processor';
 import { KeyAsDefaultValuePostProcessor } from '../post-processors/key-as-default-value.post-processor';
+import { NullAsDefaultValuePostProcessor } from '../post-processors/null-as-default-value.post-processor';
 import { PurgeObsoleteKeysPostProcessor } from '../post-processors/purge-obsolete-keys.post-processor';
 import { CompilerInterface } from '../compilers/compiler.interface';
 import { CompilerFactory } from '../compilers/compiler.factory';
@@ -87,6 +88,13 @@ export const cli = yargs
 		default: false,
 		type: 'boolean'
 	})
+	.option('null-as-default-value', {
+		alias: 'n',
+		describe: 'Use null as default value for translations',
+		default: false,
+		type: 'boolean'
+	})
+	.conflicts('key-as-default-value', 'null-as-default-value')
 	.exitProcess(true)
 	.parse(process.argv);
 
@@ -111,6 +119,8 @@ if (cli.clean) {
 }
 if (cli.keyAsDefaultValue) {
 	postProcessors.push(new KeyAsDefaultValuePostProcessor());
+} else if (cli.nullAsDefaultValue) {
+	postProcessors.push(new NullAsDefaultValuePostProcessor());
 }
 if (cli.sort) {
 	postProcessors.push(new SortByKeyPostProcessor());

src/post-processors/null-as-default-value.post-processor.ts

@@ -0,0 +1,12 @@
+import { TranslationCollection } from '../utils/translation.collection';
+import { PostProcessorInterface } from './post-processor.interface';
+
+export class NullAsDefaultValuePostProcessor implements PostProcessorInterface {
+
+	public name: string = 'NullAsDefaultValue';
+
+	public process(draft: TranslationCollection, extracted: TranslationCollection, existing: TranslationCollection): TranslationCollection {
+		return draft.map((key, val) => existing.get(key) === undefined ? null : val);
+	}
+
+}

tests/post-processors/null-as-default-value.post-processor.spec.ts

@@ -0,0 +1,42 @@
+import { expect } from 'chai';
+
+import { PostProcessorInterface } from '../../src/post-processors/post-processor.interface';
+import { NullAsDefaultValuePostProcessor } from '../../src/post-processors/null-as-default-value.post-processor';
+import { TranslationCollection } from '../../src/utils/translation.collection';
+
+describe('NullAsDefaultValuePostProcessor', () => {
+
+	let processor: PostProcessorInterface;
+
+	beforeEach(() => {
+		processor = new NullAsDefaultValuePostProcessor();
+	});
+
+	it('should use null as default value', () => {
+		const draft = new TranslationCollection({ 'String A': '' });
+		const extracted = new TranslationCollection({ 'String A': '' });
+		const existing = new TranslationCollection();
+		expect(processor.process(draft, extracted, existing).values).to.deep.equal({
+			'String A': null
+		});
+	});
+
+	it('should keep existing value even if it is an empty string', () => {
+		const draft = new TranslationCollection({ 'String A': '' });
+		const extracted = new TranslationCollection({ 'String A': '' });
+		const existing = new TranslationCollection({ 'String A': '' });
+		expect(processor.process(draft, extracted, existing).values).to.deep.equal({
+			'String A': ''
+		});
+	});
+
+	it('should keep existing value', () => {
+		const draft = new TranslationCollection({ 'String A': 'Streng A' });
+		const extracted = new TranslationCollection({ 'String A': 'Streng A' });
+		const existing = new TranslationCollection({ 'String A': 'Streng A' });
+		expect(processor.process(draft, extracted, existing).values).to.deep.equal({
+			'String A': 'Streng A'
+		});
+	});
+
+});