[英]Angular material table sort not working when using http.get()
在我嘗試使用 angular 材料表來顯示數據時,我發現當使用硬編碼的內聯 json 時,我的表按預期排序。 但是,當通過 http.get() 檢索 json 時,排序不再有效。
為說明此問題而創建的示例服務:
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable, of } from 'rxjs';
@Injectable({
providedIn: 'root',
})
export class ApiService {
constructor(private http: HttpClient) {}
getDataHttp(): Observable<any> {
return this.http.get('assets/data.json');
}
getDataInline(): Observable<any> {
var data = [
. . .
];
return of(data);
}
}
以及相應的表格組件:
import { Component, Input, OnInit, ViewChild } from '@angular/core';
import { MatSort } from '@angular/material/sort';
import { MatTableDataSource } from '@angular/material/table';
import { ApiService } from '../../services/api.service';
@Component({
selector: 'app-table',
templateUrl: './table.component.html',
styleUrls: ['./table.component.css'],
})
export class TableComponent implements OnInit {
@Input() name: string = '';
displayedColumns = ['id', 'name', 'value'];
dataSource: MatTableDataSource<any>;
@ViewChild(MatSort) sort!: MatSort;
constructor(private api: ApiService) {
this.dataSource = new MatTableDataSource();
}
ngOnInit(): void {
if (this.name === 'Inline') {
this.api.getDataInline().subscribe((response) => {
this.dataSource = new MatTableDataSource(response);
});
} else if (this.name === 'Http') {
this.api.getDataHttp().subscribe((response) => {
this.dataSource = new MatTableDataSource(response);
});
}
}
ngAfterViewInit() {
this.dataSource.sort = this.sort;
}
}
和相應的視圖:
<div>
<h5>{{ name }}</h5>
<table mat-table [dataSource]="dataSource" matSort>
<tr mat-header-row *matHeaderRowDef="displayedColumns"></tr>
<tr mat-row *matRowDef="let row; columns: displayedColumns"></tr>
<ng-container matColumnDef="id">
<th mat-header-cell *matHeaderCellDef mat-sort-header>Id</th>
<td mat-cell *matCellDef="let row">{{ row.id }}</td>
</ng-container>
<ng-container matColumnDef="name">
<th mat-header-cell *matHeaderCellDef mat-sort-header>Name</th>
<td mat-cell *matCellDef="let row">{{ row.name }}</td>
</ng-container>
<ng-container matColumnDef="value">
<th mat-header-cell *matHeaderCellDef mat-sort-header>Value</th>
<td mat-cell *matCellDef="let row">{{ row.value }}</td>
</ng-container>
</table>
</div>
Stackblitz: https://stackblitz.com/edit/angular-ivy-qk3s2y
為什么排序適用於內聯表,但不適用於 http 表?
這個:
ngAfterViewInit() {
this.dataSource.sort = this.sort;
}
在 http-request 完成之前執行。 我們需要記住這是異步的,因此您應該在收到數據后設置排序:
this.api.getDataHttp().subscribe((response) => {
this.dataSource = new MatTableDataSource(response);
this.dataSource.sort = this.sort; // <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
});
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