【发布时间】：2018-07-23 03:18:17
【问题描述】：
子组件根据是否在父表中选择记录从父组件获取输入。一旦子组件中的记录更新，父组件也会更新。我认为输入绑定是单向的？我正在尝试仅更新子表的内容。 我尝试获取可观察数据并将其传递给数组，然后返回到新的可观察数据，但这不起作用。
父组件：
import { Component } from '@angular/core';
import { MatTableDataSource } from '@angular/material';
import { SelectionModel } from '@angular/cdk/collections';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
displayedColumns = ['select', 'position', 'name', 'weight', 'symbol'];
dataSource = new MatTableDataSource<Element>(ELEMENT_DATA);
selection = new SelectionModel<Element>(true, []);
editReady: boolean = false;
recordsToEdit: Array<Element> = [];
/** Whether the number of selected elements matches the total number of rows. */
isAllSelected() {
const numSelected = this.selection.selected.length;
const numRows = this.dataSource.data.length;
return numSelected === numRows;
}
/** Selects all rows if they are not all selected; otherwise clear selection. */
masterToggle() {
this.isAllSelected() ?
this.selection.clear() :
this.dataSource.data.forEach(row => this.selection.select(row));
}
editRecords() {
this.dataSource.data.forEach(row => {
if (this.selection.isSelected(row) == true) {
this.recordsToEdit.push(row);
}
}
);
this.editReady = !this.editReady;
}
}
export interface Element {
name: string;
position: number;
weight: number;
symbol: string;
}
const ELEMENT_DATA: Element[] = [
{ position: 1, name: 'Hydrogen', weight: 1.0079, symbol: 'H' },
{ position: 2, name: 'Helium', weight: 4.0026, symbol: 'He' },
{ position: 3, name: 'Lithium', weight: 6.941, symbol: 'Li' },
{ position: 4, name: 'Beryllium', weight: 9.0122, symbol: 'Be' },
{ position: 5, name: 'Boron', weight: 10.811, symbol: 'B' },
{ position: 6, name: 'Carbon', weight: 12.0107, symbol: 'C' },
{ position: 7, name: 'Nitrogen', weight: 14.0067, symbol: 'N' },
{ position: 8, name: 'Oxygen', weight: 15.9994, symbol: 'O' },
{ position: 9, name: 'Fluorine', weight: 18.9984, symbol: 'F' },
{ position: 10, name: 'Neon', weight: 20.1797, symbol: 'Ne' },
{ position: 11, name: 'Sodium', weight: 22.9897, symbol: 'Na' },
{ position: 12, name: 'Magnesium', weight: 24.305, symbol: 'Mg' },
{ position: 13, name: 'Aluminum', weight: 26.9815, symbol: 'Al' },
{ position: 14, name: 'Silicon', weight: 28.0855, symbol: 'Si' },
{ position: 15, name: 'Phosphorus', weight: 30.9738, symbol: 'P' },
{ position: 16, name: 'Sulfur', weight: 32.065, symbol: 'S' },
{ position: 17, name: 'Chlorine', weight: 35.453, symbol: 'Cl' },
{ position: 18, name: 'Argon', weight: 39.948, symbol: 'Ar' },
{ position: 19, name: 'Potassium', weight: 39.0983, symbol: 'K' },
{ position: 20, name: 'Calcium', weight: 40.078, symbol: 'Ca' },
];
父视图：
<div class="example-container mat-elevation-z8">
<mat-table #table [dataSource]="dataSource">
<!-- Checkbox Column -->
<ng-container matColumnDef="select">
<mat-header-cell *matHeaderCellDef>
<mat-checkbox (change)="$event ? masterToggle() : null" [checked]="selection.hasValue() && isAllSelected()" [indeterminate]="selection.hasValue() && !isAllSelected()">
</mat-checkbox>
</mat-header-cell>
<mat-cell *matCellDef="let row">
<mat-checkbox (click)="$event.stopPropagation()" (change)="$event ? selection.toggle(row) : null" [checked]="selection.isSelected(row)">
</mat-checkbox>
</mat-cell>
</ng-container>
<!-- Position Column -->
<ng-container matColumnDef="position">
<mat-header-cell *matHeaderCellDef> No. </mat-header-cell>
<mat-cell *matCellDef="let element"> {{element.position}} </mat-cell>
</ng-container>
<!-- Name Column -->
<ng-container matColumnDef="name">
<mat-header-cell *matHeaderCellDef> Name </mat-header-cell>
<mat-cell *matCellDef="let element"> {{element.name}} </mat-cell>
</ng-container>
<!-- Weight Column -->
<ng-container matColumnDef="weight">
<mat-header-cell *matHeaderCellDef> Weight </mat-header-cell>
<mat-cell *matCellDef="let element"> {{element.weight}} </mat-cell>
</ng-container>
<!-- Symbol Column -->
<ng-container matColumnDef="symbol">
<mat-header-cell *matHeaderCellDef> Symbol </mat-header-cell>
<mat-cell *matCellDef="let element"> {{element.symbol}} </mat-cell>
</ng-container>
<mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
<mat-row *matRowDef="let row; columns: displayedColumns;" (click)="selection.toggle(row)">
</mat-row>
</mat-table>
</div>
<br>
<div>
<button mat-raised-button (click)="editRecords()">Edit</button>
</div>
<br>
<div *ngIf="editReady">
<app-edit-data [editRecords]=" recordsToEdit"></app-edit-data>
</div>
子视图：
<div class="example-container mat-elevation-z8">
<mat-table #table [dataSource]="dataSource">
<!-- Checkbox Column -->
<ng-container matColumnDef="select">
<mat-header-cell *matHeaderCellDef>
<mat-checkbox (change)="$event ? masterToggle() : null"
[checked]="selection.hasValue() && isAllSelected()"
[indeterminate]="selection.hasValue() && !isAllSelected()">
</mat-checkbox>
</mat-header-cell>
<mat-cell *matCellDef="let row">
<mat-checkbox (click)="$event.stopPropagation()"
(change)="$event ? selection.toggle(row) : null"
[checked]="selection.isSelected(row)">
</mat-checkbox>
</mat-cell>
</ng-container>
<!-- Position Column -->
<ng-container matColumnDef="position">
<mat-header-cell *matHeaderCellDef> No. </mat-header-cell>
<mat-cell *matCellDef="let element"> {{element.position}} </mat-cell>
</ng-container>
<!-- Name Column -->
<ng-container matColumnDef="name">
<mat-header-cell *matHeaderCellDef> Name </mat-header-cell>
<mat-cell *matCellDef="let element"> {{element.name}} </mat-cell>
</ng-container>
<!-- Weight Column -->
<ng-container matColumnDef="weight">
<mat-header-cell *matHeaderCellDef> Weight </mat-header-cell>
<mat-cell *matCellDef="let element"> {{element.weight}} </mat-cell>
</ng-container>
<!-- Symbol Column -->
<ng-container matColumnDef="symbol">
<mat-header-cell *matHeaderCellDef> Symbol </mat-header-cell>
<mat-cell *matCellDef="let element"> {{element.symbol}} </mat-cell>
</ng-container>
<mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
<mat-row *matRowDef="let row; columns: displayedColumns;"
(click)="selection.toggle(row)">
</mat-row>
</mat-table>
</div>
<br>
<div>
<button mat-raised-button (click)="changeName()">Change Name</button>
</div>
子组件：
import { Component, OnInit, Input } from '@angular/core';
import { MatTableDataSource } from '@angular/material';
import { SelectionModel } from '@angular/cdk/collections';
import { Element } from '../app.component';
@Component({
selector: 'app-edit-data',
templateUrl: './edit-data.component.html',
styleUrls: \['./edit-data.component.css'\]
})
export class EditDataComponent implements OnInit {
@Input() editRecords: Array<Element>;
dataSource = new MatTableDataSource<Element>();
constructor() { }
ngOnInit() {
this.dataSource.data = this.editRecords;
}
displayedColumns = \['select', 'position', 'name', 'weight', 'symbol'\];
selection = new SelectionModel<Element>(true, \[\]);
/** Whether the number of selected elements matches the total number of rows. */
isAllSelected() {
const numSelected = this.selection.selected.length;
const numRows = this.dataSource.data.length;
return numSelected === numRows;
}
/** Selects all rows if they are not all selected; otherwise clear selection. */
masterToggle() {
this.isAllSelected() ?
this.selection.clear() :
this.dataSource.data.forEach(row => this.selection.select(row));
}
changeName() {
this.dataSource.data.forEach(row => {
if (this.selection.isSelected(row)) {
row.name = "TEST";
}
});
}
}
【问题讨论】：
-
复制传入输入的值。如果那是像数字这样的原始类型，则复制原始类型时没有问题。但是如果你传入一个引用类型（比如一个对象或数组），你会得到一个引用的副本，它指向与父对象相同的对象/数组。您可能必须自己在孩子身上制作一个真实的副本。
-
为什么你的方括号有正斜杠？