Inserting component below mat table row only inserts into single column

Issue

I am expecting the component to be inserted across the entire row. Instead, the component appears to be inserted into the first column of the new row.

Here is a reproducible example in Angular 9: https://stackblitz.com/edit/angular-ithddx I initially encountered this issue in Angular 8 using @angular/material 8.2.3.

Clicking the first row inserts the component, but it expands the first column out rather than using the entire new row that's created.

app.component.html:

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

    <!--- Note that these columns can be defined in any order.
          The actual rendered columns are set as a property on the row definition" -->

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

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

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

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

    <tr mat-header-row *matHeaderRowDef="displayedColumns"></tr>
    <tr mat-row *matRowDef="let row; columns: displayedColumns; let index = index" 
      (click)="insertComponent(index)"
      #tableRow>
    </tr>
  </table>
</div>

app.component.ts:

    import {Component, ViewChildren, ViewContainerRef, ComponentFactoryResolver, ComponentFactory, Input} from '@angular/core';
    import {MatTableDataSource} from '@angular/material/table';

    @Component({
      selector: 'my-app',
      templateUrl: './app.component.html',
      styleUrls: [ './app.component.css' ]
    })
    export class AppComponent  {
      displayedColumns = ['position', 'name', 'weight', 'symbol'];
      dataSource = new MatTableDataSource<Element>(ELEMENT_DATA);

      @ViewChildren('tableRow', { read: ViewContainerRef }) rowContainers;
      expandedRow: number;

      constructor(private resolver: ComponentFactoryResolver) { }

      insertComponent(index: number) {
        if (this.expandedRow != null) {
          // clear old content
          this.rowContainers.toArray()[this.expandedRow].clear();
        }

        if (this.expandedRow === index) {
          this.expandedRow = null;
        } else {
          const container = this.rowContainers.toArray()[index];
          const factory: ComponentFactory<any> = this.resolver.resolveComponentFactory(InlineMessageComponent);
          const inlineComponent = container.createComponent(factory);

          inlineComponent.instance.user = this.dataSource.data[index].name;
          inlineComponent.instance.weight = this.dataSource.data[index].weight;
          this.expandedRow = index;
        }
      }
    }

InlineMessageComponent.ts

/*
* The component that will be dynamically rendered between table rows
*/ 
@Component({
  selector: 'app-inline-message',
  template: '<p>Name: {{ user }} |</p><p>| weight {{ weight }}</p>',
  styles: [`
    :host {
      display: flex;
      place-content:center;
      padding: 24px;
      color: #555555;
      font-weight: bold;
      background: rgba(0,0,0,0.1);
    }
  `]
})
export class InlineMessageComponent {
  @Input() user: string;
  @Input() weight: string;
}

---

I am expecting the same behavior as this Angular 5 example I was following. https://stackblitz.com/edit/angular-yxznk8-rongna

Things tried:

• swapping <tr mat-row> with <mat-row>
• using MatTableDataSource and inserting new rows
  • this method makes it difficult to style the new row
  • significantly more code
  • the new row displays even when empty

Solution

All you need to do, is drop the HTML in your markup and stick to the Anguler directives:

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

    <!--- Note that these columns can be defined in any order.
          The actual rendered columns are set as a property on the row definition" -->

    <!-- Position Column -->
    <ng-container matColumnDef="position">
      <mat-header-cell *matHeaderCellDef> No. </mat-header-cell>
      <mat-cell *matCellDef="let element"> {{element.position}} </mat-cell>
    </ng-container>

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

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

    <!-- Symbol Column -->
    <ng-container matColumnDef="symbol">
      <mat-header-cell *matHeaderCellDef> Symbol </mat-header-cell>
      <mat-cell *matCellDef="let element"> {{element.symbol}} </mat-cell>
    </ng-container>

    <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
    <mat-row *matRowDef="let row; columns: displayedColumns; let index = index" 
      (click)="insertComponent(index)"
      #tableRow>
    </mat-row>
  </mat-table>
</div>

Easier to parse example:

  <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>

instead of

   <tr mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>

Answered By - Austin T French