Angular Material表数据源问题

Question

我想使用 Angular Material 表。我有一个函数，它返回我想要显示的销售数组。这个功能工作正常，但我在我的 table 上看不到任何东西。如果我用一个简单的表来显示销售额，它就可以工作，所以我在数据源变量方面遇到了一些问题...

export class SaleListingComponent implements OnInit {
constructor(private saleService: SaleDomainService, private router:Router) { }

  public sales: Sale[];
  dataSource=this.sales;

  ngOnInit() {
    this.loadSales();

  }

  private loadSales() {
    this.saleService.getSales().subscribe(
      data => { this.sales = data },
      err => console.error(err),
      () => console.log("sales loaded.", JSON.stringify(this.sales))      
    );

  } 
}

 <table mat-table [dataSource]="dataSource" class="mat-elevation-z8">

    <ng-container matColumnDef="id">
      <th mat-header-cell *matHeaderCellDef> No. </th>
      <td mat-cell *matCellDef="let element"> {{element.id}} </td>
    </ng-container>

    <ng-container matColumnDef="amount">
      <th mat-header-cell *matHeaderCellDef> amount </th>
      <td mat-cell *matCellDef="let element"> {{element.amount}} </td>
    </ng-container>

    <ng-container matColumnDef="date">
      <th mat-header-cell *matHeaderCellDef> date </th>
      <td mat-cell *matCellDef="let element"> {{element.date}} </td>
    </ng-container>

    <ng-container matColumnDef="industry">
      <th mat-header-cell *matHeaderCellDef> industry </th>
      <td mat-cell *matCellDef="let element"> {{element.industry}} </td>
    </ng-container>

        <ng-container matColumnDef="price">
          <th mat-header-cell *matHeaderCellDef> price </th>
          <td mat-cell *matCellDef="let element"> {{element.price}} </td>
        </ng-container>

    <ng-container matColumnDef="prod">
      <th mat-header-cell *matHeaderCellDef> prod </th>
      <td mat-cell *matCellDef="let element"> {{element.prod}} </td>
    </ng-container>

        <ng-container matColumnDef="productType">
          <th mat-header-cell *matHeaderCellDef> productType </th>
          <td mat-cell *matCellDef="let element"> {{element.productType}} </td>
        </ng-container>

        <ng-container matColumnDef="salesman">
          <th mat-header-cell *matHeaderCellDef> salesman </th>
          <td mat-cell *matCellDef="let element"> {{element.salesman}} </td>
        </ng-container>      

    <tr mat-header-row *matHeaderRowDef="displayedColumns"></tr>
    <tr mat-row *matRowDef="let row; columns: displayedColumns;"></tr>
  </table>

Answer 1

将 [dataSource]="dataSource"更改为 `[dataSource]="sales"