javascript - 如何使用angular4将数据绑定(bind)到mat-table dataSource？

Question

我有一个 Material 数据表，我试图动态设置数据源，但它抛出错误 dataSource undefined，我是 angular2 的新手，请帮助我了解下面的代码是否有问题。

stream.component.html

<mat-table #table [dataSource]="dataSource">
   <mat-table #table [dataSource]="dataSource">

  <!-- Position Column -->
  <ng-container matColumnDef="ticketNum">
    <mat-header-cell *matHeaderCellDef> Ticket Number </mat-header-cell>
    <mat-cell *matCellDef="let element"> {{element.ticketNum}} </mat-cell>
  </ng-container>

流.component.ts

import {
    Component,
    OnInit
} from '@angular/core';
import {
    StreamService
} from '../stream.service';
import {
    MatTableDataSource
} from '@angular/material';
import * as io from 'socket.io-client';

@Component({
    selector: 'app-stream',
    templateUrl: './stream.component.html',
    styleUrls: ['./stream.component.css']
})
export class StreamComponent implements OnInit {
    displayedColumns = ['ticketNum', "assetID", "severity", "riskIndex", "riskValue", "ticketOpened", "lastModifiedDate", "eventType"];
    dataSource: MatTableDataSource < Element[] > ;
    socket = io();

    constructor(private streamService: StreamService) {};

    ngOnInit() {
        this.streamService.getAllStream().subscribe(stream => {
            this.dataSource = new MatTableDataSource(stream);
        });
        this.socket.on('newMessage', function(event) {
            console.log('Datasource', event);
            this.dataSource.MatTableDataSource.filteredData.push(event);
        });
    }
}


export interface Element {
    ticketNum: number;
    ticketOpened: number;
    eventType: string;
    riskIndex: string;
    riskValue: number;
    severity: string;
    lastModifiedDate: number;
    assetID: string;
}

Answer 1

我认为 this.socket.on('newMessage' 事件在 this.streamService.getAllStream() 解析之前触发，所以必须等到数据源实例化:

  this.streamService.getAllStream().subscribe(stream => {
        this.dataSource = new MatTableDataSource(stream);
        this.socket.on('newMessage', (event) => {  // <-- here
          console.log('Datasource', event);
           this.dataSource.data.push(event);
           this.dataSource.data = [...this.dataSource.data]
        });
    });
}