垫子排序不适用于垫子桌子 [英] mat-sort not working on mat-table

问题描述

我的mat-table工作正常，但是当按照官方api文档添加mat-sort时，它在ngAfterViewInit失败，并显示以下消息

My mat-table is working fine, but when adding mat-sort following the official api documentation, it fails at the ngAfterViewInit with the following message

无法设置未定义的属性"sort" 在ViewFeedbackComponent.ngAfterViewInit

Cannot set property 'sort' of undefined at ViewFeedbackComponent.ngAfterViewInit

已经有关于此问题的SO帖子(请参阅以下链接) Mat-table排序演示不起作用，但是我仍然无法使它起作用.

There is already a SO post on this issue (see following link) Mat-table Sorting Demo not Working but I still am not able to get it working.

有人发现问题了吗?官方示例使用组件本身中定义的静态" MatTableDataSource，但是我是从后端查询的.

Does somebody spot the issue? The official example works with a "static" MatTableDataSourcedefined in the component itself, I am querying from my back-end, however.

任何帮助将不胜感激！

MatSortModule已导入到app.module.ts中，mat-sort-header指令已应用于列，并且ngAfterViewInit已与官方示例中的完全相同...

MatSortModule is already imported in app.module.ts, mat-sort-header directives are applied to the columns and the ngAfterViewInit is already exactly like in the official example...

import {  Component,  OnInit,  ViewEncapsulation,  ViewChild,  AfterViewInit} from '@angular/core';
import {  Feedback} from '../../../../../models/feedback';
import {  FeedbackService} from '../../services/feedback.service';
import {  MatTableDataSource,  MatSort} from '@angular/material';


@Component({
  selector: 'app-view-feedback',
  templateUrl: './view-feedback.component.html',
  styleUrls: ['./view-feedback.component.css'],
  encapsulation: ViewEncapsulation.Emulated
})
export class ViewFeedbackComponent implements OnInit, AfterViewInit {

  feedbacks: Feedback[] = [];
  showSpinner: boolean = true;
  displayedColumns: String[] = [
    'id',
    'user',
    'timestamp',
    'stars'
  ];
  dataSource: MatTableDataSource < Feedback > ;

  @ViewChild(MatSort) sort: MatSort;

  constructor(private _feedbackService: FeedbackService) {}

  ngOnInit() {
    this._feedbackService.getFeedback.subscribe(
      res => {
        this.feedbacks = res;
        this.dataSource = new MatTableDataSource(this.feedbacks);
      }
    );

  }

  ngAfterViewInit() {
    this.dataSource.sort = this.sort;
  }


}

<div class="mat-tbl-container mat-elevation-z8">
  <mat-table #tbl [dataSource]="dataSource" matSort>

    <!-- column definitions -->
    <ng-container matColumnDef="id">
      <mat-header-cell *matHeaderCellDef mat-sort-header>Id</mat-header-cell>
      <mat-cell *matCellDef="let r"> {{r._id}} </mat-cell>
    </ng-container>

    <ng-container matColumnDef="user">
      <mat-header-cell *matHeaderCellDef mat-sort-header>User Id</mat-header-cell>
      <mat-cell *matCellDef="let r"> {{r.user}} </mat-cell>
    </ng-container>

    <ng-container matColumnDef="timestamp">
      <mat-header-cell *matHeaderCellDef mat-sort-header>Date</mat-header-cell>
      <mat-cell *matCellDef="let r"> {{r.timestamp}} </mat-cell>
    </ng-container>

    <ng-container matColumnDef="stars">
      <mat-header-cell *matHeaderCellDef mat-sort-header>Stars</mat-header-cell>
      <mat-cell *matCellDef="let r"> {{r.stars}} </mat-cell>
    </ng-container>

    <!-- tbl display settings -->
    <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
    <mat-row *matRowDef="let row; columns: displayedColumns;"></mat-row>

  </mat-table>

推荐答案

问题是下一段代码

  ngAfterViewInit() {
    this.dataSource.sort = this.sort;
  }

发生在您实际上在这里预订表之前

is happen before you actually got your table in subscription here:

  ngOnInit() {
    this._feedbackService.getFeedback.subscribe(
      res => {
        this.feedbacks = res;
        this.dataSource = new MatTableDataSource(this.feedbacks);
      }
    );

  }

作为一种可能的解决方案，您可以通过Observable.zip同步ngAfterViewInit呼叫和getFeedback订阅.请参考 RxJS zip文档

As a possible solution, you could synchronize ngAfterViewInit call and getFeedback subscription via Observable.zip. Please refer to RxJS zip documentation

这篇关于垫子排序不适用于垫子桌子的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！