Javascript 角度材质-比较并迭代两个数据源

我使用Mat表格以网格格式显示记录。我还通过使用两个不同的数据源实现了可扩展行

第一个数据源将具有不重复的记录，当我单击一行时，它将展开并显示第二个数据源中具有重复记录的记录。我的要求是在展开的行中只显示匹配的记录，但它显示来自第二个数据源的所有记录

我使用了*ngFor和*ngIf选项，但它抛出了错误。有人能告诉我正确的密码吗

HTML代码：

<mat-table [dataSource]="mDataSource1" multiTemplateDataRows matSort>

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

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

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

    <ng-container matColumnDef="expandedDetail">
        <mat-table [dataSource]="mDataSource2" matSort>
          <ng-container *ngIf = "element.Id === item.Id">              
            <ng-container matColumnDef="Id">
                <mat-header-cell *matHeaderCellDef mat-sort-header>Id</mat-header-cell>
                <mat-cell *matCellDef="let item">{{item.Id}}</mat-cell>
            </ng-container>

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

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

            <mat-row *matRowDef="let row; columns: mDataSource2Columns;"></mat-row>
          </ng-container>
        </mat-table>
    </ng-container>

    <mat-header-row *matHeaderRowDef="mDataSource1Columns"></mat-header-row>
    <mat-row *matRowDef="let row; columns: mDataSource1Columns;" class="example-element-row"
        [class.example-expanded-row]="expandedElement === row"
        (click)="expandedElement = expandedElement === row ? null : row"
        (mouseover)="row.gridHovered = true" (mouseout)="row.gridHovered = false">
    </mat-row>

    <mat-row *matRowDef="let row; columns: ['expandedDetail']" class="example-detail-row"></mat-row>

    <mat-footer-row *matFooterRowDef="['loading']" [ngClass]="{'hide':mDataSource1!=null}">
    </mat-footer-row>
    <mat-footer-row *matFooterRowDef="['noData']"
        [ngClass]="{'hide':!(mDataSource1!=null && mDataSource1.data.length==0)}">
    </mat-footer-row>

</mat-table>


mDataSource1 =  [
      {Id:1, name: 'ABC', weight: 40 },
      {Id:2, name: 'DEF', weight: 45 },
      {Id:4, name: 'GHI', weight: 85 }
    ]

mDataSource2 = [
  {Id:1, name: 'ABC', weight: 10 },
  {Id:1, name: 'ABC', weight: 14 },
  {Id:1, name: 'ABC', weight: 16 },
  {Id:2, name: 'DEF', weight: 23 },
  {Id:2, name: 'DEF', weight: 22 },
  {Id:4, name: 'GHI', weight: 44 },
  {Id:4, name: 'GHI', weight: 41 }
]

---

我在你的例子中没有看到ngFor。 Angular不允许在一个标记上使用多个结构指令。 与此相反：

<div *ngIf="true" *ngFor="let..."></div>

用这个

<ng-container *ngIf="true">
  <div *ngFor="let..."></div>
</ng-container>

不要担心ng容器，Angular不会将其放入DOM中

<ng-container *ngIf="true">
  <div *ngFor="let..."></div>
</ng-container>