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fix(Common): allow null/undefined values for `NgForTrackBy` 

Reverts a breaking change introduced in 2.4.1 by #13420
fixes #13641
This commit is contained in:
Victor Berchet 2017-01-03 15:14:30 -08:00 committed by Igor Minar
parent f822f9599c
commit f88cd2f22e
2 changed files with 27 additions and 10 deletions
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12
modules/@angular/common/src/directives/ng_for.ts
View File

@ -6,7 +6,7 @@
* found in the LICENSE file at https://angular.io/license
*/
import {ChangeDetectorRef, CollectionChangeRecord, DefaultIterableDiffer, Directive, DoCheck, EmbeddedViewRef, Input, IterableDiffer, IterableDiffers, OnChanges, SimpleChanges, TemplateRef, TrackByFn, ViewContainerRef} from '@angular/core';
import {ChangeDetectorRef, CollectionChangeRecord, DefaultIterableDiffer, Directive, DoCheck, EmbeddedViewRef, Input, IterableDiffer, IterableDiffers, OnChanges, SimpleChanges, TemplateRef, TrackByFn, ViewContainerRef, isDevMode} from '@angular/core';
import {getTypeNameForDebugging} from '../facade/lang';
@ -91,9 +91,13 @@ export class NgFor implements DoCheck, OnChanges {
@Input() ngForOf: any;
@Input()
set ngForTrackBy(fn: TrackByFn) {
if (typeof fn !== 'function') {
throw new Error(`trackBy must be a function, but received ${JSON.stringify(fn)}.
See https://angular.io/docs/ts/latest/api/common/index/NgFor-directive.html#!#change-propagation for more information.`);
if (isDevMode() && fn != null && typeof fn !== 'function') {
// TODO(vicb): use a log service once there is a public one available
if (<any>console && <any>console.warn) {
console.warn(
`trackBy must be a function, but received ${JSON.stringify(fn)}. ` +
`See https://angular.io/docs/ts/latest/api/common/index/NgFor-directive.html#!#change-propagation for more information.`);
}
}
this._trackByFn = fn;
}

25
modules/@angular/common/test/directives/ng_for_spec.ts
View File

@ -294,14 +294,25 @@ export function main() {
}));
describe('track by', () => {
it('should throw if trackBy is not a function', async(() => {
it('should console.warn if trackBy is not a function', async(() => {
// TODO(vicb): expect a warning message when we have a proper log service
const template =
`<template ngFor let-item [ngForOf]="items" [ngForTrackBy]="item?.id"></template>`;
`<template ngFor let-item [ngForOf]="items" [ngForTrackBy]="value"></template>`;
fixture = createTestComponent(template);
fixture.componentInstance.value = 0;
fixture.detectChanges();
}));
getComponent().items = [{id: 1}, {id: 2}];
expect(() => fixture.detectChanges())
.toThrowError(/trackBy must be a function, but received null/);
it('should track by identity when trackBy is to `null` or `undefined`', async(() => {
// TODO(vicb): expect no warning message when we have a proper log service
const template =
`<template ngFor let-item [ngForOf]="items" [ngForTrackBy]="value">{{ item }}</template>`;
fixture = createTestComponent(template);
fixture.componentInstance.items = ['a', 'b', 'c'];
fixture.componentInstance.value = null;
detectChangesAndExpectText('abc');
fixture.componentInstance.value = undefined;
detectChangesAndExpectText('abc');
}));
it('should set the context to the component instance', async(() => {
@ -343,6 +354,7 @@ export function main() {
getComponent().items = [{'id': 'a', 'color': 'red'}];
detectChangesAndExpectText('red');
}));
it('should move items around and keep them updated ', async(() => {
const template =
`<div><template ngFor let-item [ngForOf]="items" [ngForTrackBy]="trackById">{{item['color']}}</template></div>`;
@ -378,6 +390,7 @@ class Foo {
@Component({selector: 'test-cmp', template: ''})
class TestComponent {
@ContentChild(TemplateRef) contentTpl: TemplateRef<Object>;
value: any;
items: any[] = [1, 2];
trackById(index: number, item: any): string { return item['id']; }
trackByIndex(index: number, item: any): number { return index; }
@ -394,4 +407,4 @@ const TEMPLATE = '<div><span template="ngFor let item of items">{{item.toString(
function createTestComponent(template: string = TEMPLATE): ComponentFixture<TestComponent> {
return TestBed.overrideComponent(TestComponent, {set: {template: template}})
.createComponent(TestComponent);
}
}