在动态材料表模板中显示嵌套对象

Question

我想在表格中显示 weight.name。我能够通过转换数据来做到这一点。但是，我不想以任何形式操作数据。我尝试将行模板（displayedColumns）中的weight更改为weight.name，但根本没有返回任何数据。

App.component.html

<table mat-table [dataSource]="dataSource">
  <ng-container *ngFor="let col of displayedColumns" [matColumnDef]="col">
    <th mat-header-cell *matHeaderCellDef> {{col}} </th>
    <td mat-cell *matCellDef="let element"> {{element[col]}} </td>
  </ng-container>

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

App.component.ts

import { Component } from '@angular/core';

export interface PeriodicElement {
  name: string;
  position: number;
  weight: any;
  symbol: string;
}

const ELEMENT_DATA: PeriodicElement[] = [
  {position: 1, name: 'Hydrogen', weight: {name: 5.55}, symbol: 'H'},
  {position: 2, name: 'Helium', weight: {name: 5.55}, symbol: 'He'},
  {position: 3, name: 'Lithium', weight: {name: 5.55}, symbol: 'Li'},
  {position: 4, name: 'Beryllium', weight: {name: 5.55}, symbol: 'Be'},
  {position: 5, name: 'Boron', weight: {name: 5.55}, symbol: 'B'},
  {position: 6, name: 'Carbon', weight: {name: 5.55}, symbol: 'C'},
  {position: 7, name: 'Nitrogen', weight: {name: 5.55}, symbol: 'N'},
  {position: 8, name: 'Oxygen', weight: {name: 5.55}, symbol: 'O'},
  {position: 9, name: 'Fluorine', weight: {name: 5.55}, symbol: 'F'},
  {position: 10, name: 'Neon', weight: {name: 5.55}, symbol: 'Ne'},
];

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

这是供参考的 stackblitz 链接。 https://stackblitz.com/edit/angular-mat-table-dynamic-columns-x36dvr?file=src%2Fapp%2Fapp.component.ts

Answer 1

您的问题是您将权重列显示为 row[col] 或 rowInstance['weight'] 显示权重对象的 toString() 导致 [object object]。

1. 将您的表格模板修改为：

   <table mat-table [dataSource]="dataSource">
        <ng-container matColumnDef="position"> 
            <mat-header-cell *matHeaderCellDef> Position </mat-header-cell>
            <mat-cell *matCellDef="let row">{{row.position}}</mat-cell>
        </ng-container> 
        <ng-container matColumnDef="name"> 
            <mat-header-cell *matHeaderCellDef> Name </mat-header-cell>
            <mat-cell *matCellDef="let row">{{row.name}}</mat-cell>
        </ng-container>
        <ng-container matColumnDef="weightName"> 
            <mat-header-cell *matHeaderCellDef> Weight </mat-header-cell>
            <mat-cell *matCellDef="let row">{{row.weight.name}}</mat-cell>
        </ng-container>
        <ng-container matColumnDef="symbol"> 
            <mat-header-cell *matHeaderCellDef> Symbol </mat-header-cell>
            <mat-cell *matCellDef="let row">{{row.symbol}}</mat-cell>
        </ng-container>
   
        <mat-header-row *matHeaderRowDef="displayedColumns">
        </mat-header-row>
        <mat-row *matRowDef="let row; columns: displayedColumns;">
        </mat-row>
    </table>
   

在您的 ts 文件中，将显示列修改为：

  `displayedColumns: string[] = ['position', 'name', 'weightName', 'symbol'];`

https://stackblitz.com/edit/angular-mat-table-dynamic-columns-w7do4c?file=src/app/app.component.html

1. 将您的上游数据模型转换/展平为如下所示，并保持您的模板不变。

   [{position: 1, name: 'Hydrogen', weightName: 5.55, symbol: 'H'},...]

Answer 2

我遇到过类似的问题，我解决了如下。

1. 更新displayedColumns: string[] = ['position', 'name', 'weight.name', 'symbol'];
2. 在app.component.ts中写一个方法如下

findColumnValue = (element:unknown, column:string):string => <string>column.split('.').reduce((acc, cur) => acc[cur], element);

1. 更新html文件如下

<ng-container [matColumnDef]="column" *ngFor="let column of displayedColumns">
    <th mat-header-cell *matHeaderCellDef mat-sort-header> {{column.split('.')[0]}} </th>
    <td mat-cell *matCellDef="let element"> {{findColumnValue(element, column)}} </td>
</ng-container>

4. 如果你对eval方法没问题，你可以如下使用它

findColumnValue = (element:unknown, column:string):string => eval(`element.${column}`);

Answer 3

您可以在显示的列数组中使用点表示法访问嵌套对象

例子：

  displayedColumns: string[] = ['position', 'name', 'weight.name', 'symbol'];

在表格 HTML 中，您需要在 matColDef 中引用点符号 weight.name

您的 HTML：

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