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[英]Angular 4: `ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked
[英]Angular4/ngrx - ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked
用我的角度代碼,管理頁面列出了數據表組件中的項目,一旦單擊其中一個數據項,管理權限組件就會打開並顯示與單擊的項目相關的數據。
一旦單擊,我得到這個錯誤:
ERROR Error: ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked. Previous value: 'false'. Current value: 'true'.
at viewDebugError (core.es5.js:8434)
at expressionChangedAfterItHasBeenCheckedError (core.es5.js:8412)
at checkBindingNoChanges (core.es5.js:8576)
at checkNoChangesNodeInline (core.es5.js:12448)
at checkNoChangesNode (core.es5.js:12422)
at debugCheckNoChangesNode (core.es5.js:13202)
at debugCheckDirectivesFn (core.es5.js:13104)
at Object.eval [as updateDirectives] (AdminComponent.html:21)
at Object.debugUpdateDirectives [as updateDirectives] (core.es5.js:13086)
at checkNoChangesView (core.es5.js:12242)
創建管理員權限的子組件后,我開始收到錯誤消息
admin.component.html:
<data-table [table]='table' [data]="data" (onSelect)="onItemSelect($event)"></data-table>
<admin-right *ngIf="showRight"
[item]="item"
[rightContent]="rightContent"></admin-right>
數據table.component.ts:
@Component({
...
changeDetection: ChangeDetectionStrategy.OnPush
})
export class DataTableComponent implements OnInit {
constructor(
private cdRef:ChangeDetectorRef
) { }
ngOnInit() {
this.cdRef.detectChanges();
}
right.component.ts:
@Component({
....
changeDetection: ChangeDetectionStrategy.OnPush
})
export class RightComponent implements OnInit {
@Input() item;
@Input() rightContent;
constructor( private cdRef:ChangeDetectorRef) { }
ngOnInit() {
this.cdRef.detectChanges();
}
此錯誤來自以下事實:已在Angular的生命周期中檢查了一個變量,並且在生命周期結束后嘗試更改它。
這是很常見的錯誤,通常在生產模式下不會重現該錯誤。
如果要更正它,要么不更改變量的值,要么使用超時,通過setTimeout(() => {/* what you do after the user clicked here */})
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