Question

我的mat-table工作正常，但是在官方api文档之后添加mat-sort时，它在ngAfterViewInit中失败并显示以下消息

无法设置属性＆＃39;排序＆＃39;未定义的在ViewFeedbackComponent.ngAfterViewInit

此问题上已有SO帖子（请参阅以下链接）Mat-table Sorting Demo not Working但我仍然无法使其正常运行。

有人发现了这个问题吗？官方示例适用于＆＃34;静态＆＃34;然而，在组件本身中定义了MatTableDataSource，我从后端查询。

非常感谢任何帮助！

matSortModule已经在app.module.ts中导入，mat-sort-header指令应用于列，ngAfterViewInit已经完全像官方示例中那样...

＆＃13;

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;
  }


}

＆＃13;

<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>

＆＃13;

Answer 1

问题是下一段代码

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

在你真正在这里订阅你的桌子之前就已经发生了：

  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ngAfterViewInit同步getFeedback来电和Observable.zip订阅。请参阅RxJS zip documentation

Answer 2

请确保从API获取数据时添加了{static: false}

@ViewChild(MatSort, {static: false}) sort: MatSort;

Answer 3

对于matSort来说，类型定义很重要，至少我发现了这一点。因此，在代码中输入type： dataSource：MatTableDataSource;不起作用。这里必须定义一个类型才能使其正常工作，尝试定义一个接口并将其传递给MatTableDataSource的泛型。另外，matColumnDef必须匹配定义类型的属性名称。

Answer 4

我使用旧版角度材质中的前一种排序方法示例。最新的角度材质排序示例使用ngAfterViewInit()来调用排序this.dataSource.sort = this.sort;我无法使用新示例进行排序。旧的排序方法使用扩展DataSource。我能够使用来自'@ angular / cdk / table'的新路径`import {DataSource}导入DataSource;

import { Component, ViewChild, Inject, OnInit, ElementRef } from '@angular/core';
import { MatTableDataSource, MatSort } from '@angular/material';
import { DataSource } from '@angular/cdk/table';
import { Observable } from 'rxjs/Observable';
import { HttpClient, HttpResponse, HttpHeaders, HttpRequest} from '@angular/common/http';
import 'rxjs/add/operator/startWith';
import 'rxjs/add/observable/merge';
import 'rxjs/add/observable/of';
import 'rxjs/add/operator/map';

export interface Data {}

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})

export class AppComponent implements OnInit {

  myData: Array < any > ;
  displayedColumns = ['id', 'name'];

  dataSource: MyDataSource;

  @ViewChild(MatSort) sort: MatSort;

  constructor(private http: HttpClient) {}

 getData() {
    let url = 'https://api.mydatafeeds.com/v1.1/cumulative_player_data.json?';
    let headers = new HttpHeaders({ "Authorization": "123ykiki456789123456" });
    this.http.get(url, {headers})
      .subscribe(res => {
        this.myData = res;
        this.dataSource = new MyDataSource(this.myData, this.sort);
      });
  }

  ngOnInit() {
    this.getData();
  }
}

export class MyDataSource extends DataSource < any > {
  constructor(private dataBase: Data[], private sort: MatSort) {
    super();
  }
  /** Connect function called by the table to retrieve one stream containing the data to render. */
  connect(): Observable < Data[] > {
    const displayDataChanges = [
      Observable.of(this.dataBase),
      this.sort.sortChange,
    ];

    return Observable.merge(...displayDataChanges).map(() => {
      return this.getSortedData();
    });
  }

  disconnect() {}

  /** Returns a sorted copy of the database data. */
  getSortedData(): Data[] {
    const data = this.dataBase.slice();
    if (!this.sort.active || this.sort.direction == '') { return data; }

    return data.sort((a, b) => {

      let propertyA: number | string = '';
      let propertyB: number | string = '';

      switch (this.sort.active) {
        case 'id':
          [propertyA, propertyB] = [a.id, b.id];
          break;
        case 'name':
          [propertyA, propertyB] = [a.name, b.name];
          break;

      }

      let valueA = isNaN(+propertyA) ? propertyA : +propertyA;
      let valueB = isNaN(+propertyB) ? propertyB : +propertyB;

      return (valueA < valueB ? -1 : 1) * (this.sort.direction == 'asc' ? 1 : -1);
    });

  }

}

<mat-table #table [dataSource]="dataSource" matSort>
  <ng-container matColumnDef="id">
    <mat-header-cell *matHeaderCellDef mat-sort-header> Id </mat-header-cell>
    <mat-cell *matCellDef="let data"> <b>{{data.id}}.</b>
    </mat-cell>
  </ng-container>
  <ng-container matColumnDef="name">
    <mat-header-cell *matHeaderCellDef mat-sort-header> Id </mat-header-cell>
    <mat-cell *matCellDef="let data"> <b>{{data.name}}.</b>
    </mat-cell>
  </ng-container>
  <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
  <mat-row *matRowDef="let data; columns: displayedColumns;"></mat-row>
</mat-table>

Answer 5

我重新定义了从MatTableDataSource继承过来的连接方法...

Answer 6

在angular 7中，将以下示例用于两个分页器，但将分页器替换为sort。

https://stackblitz.com/edit/data-table-multiple-data-source

以下是该问题的重复内容：

Multiple mat-table with MatSort within the same component

Answer 7

一个简单的解决方案是在ngAfterViewInit中声明排序，而不是在“ this._feedbackService.getFeedback.subscribe”中得到结果后声明。

解决方法如下。

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

        this.dataSource.sort = this.sort; //this will solve your problem

      }
    );

  }

上面的一个对我来说很完美。

谢谢

mat-sort不能在mat-table

7 个答案: