refactor(common): create an NgFor alias for NgForOf directive (#47309)

This commit adds a re-export of the `NgForOf` class as `NgFor` to improve the DX for cases when the directive is used as standalone. Developers can import `NgFor` class, which better matches the `ngFor` attribute used in a template.

PR Close #47309

goldens/public-api/common/index.md

@@ -450,7 +450,7 @@ export class NgComponentOutlet implements OnChanges, OnDestroy {
 }
 
 // @public
-export class NgForOf<T, U extends NgIterable<T> = NgIterable<T>> implements DoCheck {
+class NgForOf<T, U extends NgIterable<T> = NgIterable<T>> implements DoCheck {
     constructor(_viewContainer: ViewContainerRef, _template: TemplateRef<NgForOfContext<T, U>>, _differs: IterableDiffers);
     ngDoCheck(): void;
     set ngForOf(ngForOf: U & NgIterable<T> | undefined | null);
@@ -464,6 +464,8 @@ export class NgForOf<T, U extends NgIterable<T> = NgIterable<T>> implements DoCh
     // (undocumented)
     static ɵfac: i0.ɵɵFactoryDeclaration<NgForOf<any, any>, never>;
 }
+export { NgForOf as NgFor }
+export { NgForOf }
 
 // @public (undocumented)
 export class NgForOfContext<T, U extends NgIterable<T> = NgIterable<T>> {

packages/common/src/common.ts

@@ -20,7 +20,7 @@ export {registerLocaleData} from './i18n/locale_data';
 export {Plural, NumberFormatStyle, FormStyle, Time, TranslationWidth, FormatWidth, NumberSymbol, WeekDay, getNumberOfCurrencyDigits, getCurrencySymbol, getLocaleDayPeriods, getLocaleDayNames, getLocaleMonthNames, getLocaleId, getLocaleEraNames, getLocaleWeekEndRange, getLocaleFirstDayOfWeek, getLocaleDateFormat, getLocaleDateTimeFormat, getLocaleExtraDayPeriodRules, getLocaleExtraDayPeriods, getLocalePluralCase, getLocaleTimeFormat, getLocaleNumberSymbol, getLocaleNumberFormat, getLocaleCurrencyCode, getLocaleCurrencyName, getLocaleCurrencySymbol, getLocaleDirection} from './i18n/locale_data_api';
 export {parseCookieValue as ɵparseCookieValue} from './cookie';
 export {CommonModule} from './common_module';
-export {NgClass, NgForOf, NgForOfContext, NgIf, NgIfContext, NgPlural, NgPluralCase, NgStyle, NgSwitch, NgSwitchCase, NgSwitchDefault, NgTemplateOutlet, NgComponentOutlet} from './directives/index';
+export {NgClass, NgFor, NgForOf, NgForOfContext, NgIf, NgIfContext, NgPlural, NgPluralCase, NgStyle, NgSwitch, NgSwitchCase, NgSwitchDefault, NgTemplateOutlet, NgComponentOutlet} from './directives/index';
 export {DOCUMENT} from './dom_tokens';
 export {AsyncPipe, DatePipe, DATE_PIPE_DEFAULT_TIMEZONE, I18nPluralPipe, I18nSelectPipe, JsonPipe, LowerCasePipe, CurrencyPipe, DecimalPipe, PercentPipe, SlicePipe, UpperCasePipe, TitleCasePipe, KeyValuePipe, KeyValue} from './pipes/index';
 export {PLATFORM_BROWSER_ID as ɵPLATFORM_BROWSER_ID, PLATFORM_SERVER_ID as ɵPLATFORM_SERVER_ID, PLATFORM_WORKER_APP_ID as ɵPLATFORM_WORKER_APP_ID, PLATFORM_WORKER_UI_ID as ɵPLATFORM_WORKER_UI_ID, isPlatformBrowser, isPlatformServer, isPlatformWorkerApp, isPlatformWorkerUi} from './platform_id';

packages/common/src/directives/index.ts

@@ -7,9 +7,10 @@
  */
 
 import {Provider} from '@angular/core';
+
 import {NgClass} from './ng_class';
 import {NgComponentOutlet} from './ng_component_outlet';
-import {NgForOf, NgForOfContext} from './ng_for_of';
+import {NgFor, NgForOf, NgForOfContext} from './ng_for_of';
 import {NgIf, NgIfContext} from './ng_if';
 import {NgPlural, NgPluralCase} from './ng_plural';
 import {NgStyle} from './ng_style';
@@ -19,6 +20,7 @@ import {NgTemplateOutlet} from './ng_template_outlet';
 export {
   NgClass,
   NgComponentOutlet,
+  NgFor,
   NgForOf,
   NgForOfContext,
   NgIf,

packages/common/src/directives/ng_for_of.ts

@@ -290,6 +290,11 @@ export class NgForOf<T, U extends NgIterable<T> = NgIterable<T>> implements DoCh
   }
 }
 
+// Also export the `NgForOf` class as `NgFor` to improve the DX for
+// cases when the directive is used as standalone, so the class name
+// matches the CSS selector (*ngFor).
+export {NgForOf as NgFor};
+
 function applyViewChange<T>(
     view: EmbeddedViewRef<NgForOfContext<T>>, record: IterableChangeRecord<T>) {
   view.context.$implicit = record.item;

packages/common/test/directives/ng_for_spec.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {CommonModule, NgForOf} from '@angular/common';
+import {CommonModule, NgFor, NgForOf} from '@angular/common';
 import {Component} from '@angular/core';
 import {ComponentFixture, TestBed, waitForAsync} from '@angular/core/testing';
 import {By} from '@angular/platform-browser/src/dom/debug/by';
@@ -408,6 +408,25 @@ let thisArg: any;
 
       expect(fixture.nativeElement.textContent).toBe('1|2|3|');
     });
+
+    it('should be available as a standalone directive using an `NgFor` alias', () => {
+      @Component({
+        selector: 'test-component',
+        imports: [NgFor],
+        template: `
+          <ng-container *ngFor="let item of items">{{ item }}|</ng-container>
+        `,
+        standalone: true,
+      })
+      class TestComponent {
+        items = [1, 2, 3];
+      }
+
+      const fixture = TestBed.createComponent(TestComponent);
+      fixture.detectChanges();
+
+      expect(fixture.nativeElement.textContent).toBe('1|2|3|');
+    });
   });
 }
 

packages/compiler-cli/src/ngtsc/typecheck/extended/checks/missing_control_flow_directive/index.ts

@@ -24,7 +24,7 @@ import {TemplateCheckFactory, TemplateCheckWithVisitor, TemplateContext} from '.
  * `CommonModule` is included, the `ngSwitch` would also be covered.
  */
 export const KNOWN_CONTROL_FLOW_DIRECTIVES = new Map([
-  ['ngIf', 'NgIf'], ['ngFor', 'NgForOf'], ['ngSwitchCase', 'NgSwitchCase'],
+  ['ngIf', 'NgIf'], ['ngFor', 'NgFor'], ['ngSwitchCase', 'NgSwitchCase'],
   ['ngSwitchDefault', 'NgSwitchDefault']
 ]);
 

packages/core/src/render3/instructions/element_validation.ts

@@ -282,7 +282,7 @@ function getTemplateLocationDetails(lView: LView): string {
  * that the `CommonModule` should also be included.
  */
 export const KNOWN_CONTROL_FLOW_DIRECTIVES = new Map([
-  ['ngIf', 'NgIf'], ['ngFor', 'NgForOf'], ['ngSwitchCase', 'NgSwitchCase'],
+  ['ngIf', 'NgIf'], ['ngFor', 'NgFor'], ['ngSwitchCase', 'NgSwitchCase'],
   ['ngSwitchDefault', 'NgSwitchDefault']
 ]);
 /**