Angular Material：如何基于单一数据源通过服务展示多组不同数据的MatTable

当前已实现单一数据源的MatTable，现需通过服务按weight字段分组，生成多个独立MatTable分别展示同组数据。以下是改造方案：

1. 创建数据分组服务 #

封装通用的分组逻辑，可在多个组件中复用：

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

@Injectable({ providedIn: 'root' })
export class DataGroupingService {
  // 按指定字段对数据进行分组
  groupByField(data: any[], field: string): Map<string, any[]> {
    return data.reduce((groupMap, item) => {
      const groupKey = item[field];
      if (!groupMap.has(groupKey)) {
        groupMap.set(groupKey, []);
      }
      groupMap.get(groupKey)!.push(item);
      return groupMap;
    }, new Map<string, any[]>());
  }
}

2. 改造组件逻辑 #

注入分组服务，处理原始数据为分组结构，并为每个分组创建独立数据源：

import { Component } from '@angular/core';
import { DataSource } from '@angular/cdk/collections';
import { Observable, of } from 'rxjs';
import { DataGroupingService } from './data-grouping.service';

const ELEMENT_DATA: any[] = [
  {position: 1, name: 'Hydrogen', weight: 1.0079, symbol: 'H'},
  {position: 2, name: 'Helium', weight: 4.0026, symbol: 'He'},
  {position: 3, name: 'Lithium', weight: 6.941, symbol: 'Li'},
  {position: 4, name: 'Beryllium', weight: 9.0122, symbol: 'Be'},
  {position: 5, name: 'Boron', weight: 10.811, symbol: 'B'},
  {position: 6, name: 'Carbon', weight: 12.0107, symbol: 'C'},
  {position: 7, name: 'Nitrogen', weight: 14.0067, symbol: 'N'},
  {position: 8, name: 'Oxygen', weight: 15.9994, symbol: 'O'},
  {position: 9, name: 'Fluorine', weight: 18.9984, symbol: 'F'},
  {position: 10, name: 'Neon', weight: 20.1797, symbol: 'Ne'},
  {position: 11, name: 'Sodium', weight: 22.9897, symbol: 'Na'},
  {position: 12, name: 'Magnesium', weight: 24.305, symbol: 'Mg'},
  {position: 13, name: 'Aluminum', weight: 26.9815, symbol: 'Al'},
  {position: 14, name: 'Silicon', weight: 28.0855, symbol: 'Si'},
  {position: 15, name: 'Phosphorus', weight: 30.9738, symbol: 'P'},
  {position: 16, name: 'Sulfur', weight: 32.065, symbol: 'S'},
  {position: 17, name: 'Chlorine', weight: 35.453, symbol: 'Cl'},
  {position: 18, name: 'Argon', weight: 39.948, symbol: 'Ar'},
  {position: 19, name: 'Potassium', weight: 39.0983, symbol: 'K'},
  {position: 20, name: 'Calcium', weight: 40.078, symbol: 'Ca'},
];

export class GroupedTableDataSource extends DataSource<any> {
  constructor(private dataSet: any[]) {
    super();
  }

  connect(): Observable<any[]> {
    return of(this.dataSet);
  }

  disconnect() {}
}

@Component({
  selector: 'app-grouped-tables',
  templateUrl: './grouped-tables.component.html'
})
export class GroupedTablesComponent {
  columns = [
    { columnDef: 'position', header: 'No.',    cell: (element: any) => `${element.position}` },
    { columnDef: 'name',     header: 'Name',   cell: (element: any) => `${element.name}`     },
    { columnDef: 'weight',   header: 'Weight', cell: (element: any) => `${element.weight}`   },
    { columnDef: 'symbol',   header: 'Symbol', cell: (element: any) => `${element.symbol}`   },
  ];
  displayedColumns = this.columns.map(c => c.columnDef);
  groupedDataSources: Map<string, GroupedTableDataSource>;

  constructor(private groupingService: DataGroupingService) {
    // 按weight字段分组，为每个分组生成独立数据源
    const groupedDataMap = this.groupingService.groupByField(ELEMENT_DATA, 'weight');
    this.groupedDataSources = new Map(
      Array.from(groupedDataMap.entries()).map(([key, data]) => [key, new GroupedTableDataSource(data)])
    );
  }
}

3. 修改HTML模板 #

循环渲染每个分组对应的MatTable，同时显示分组标识：

<div *ngFor="let [weightKey, tableDataSource] of groupedDataSources | keyvalue">
  <h3>分组：Weight = {{ weightKey }}</h3>
  <mat-table [dataSource]="tableDataSource" class="mat-elevation-z2">
    <ng-container *ngFor="let column of columns" [cdkColumnDef]="column.columnDef">
      <mat-header-cell *cdkHeaderCellDef>{{ column.header }}</mat-header-cell>
      <mat-cell *cdkCellDef="let row">{{ column.cell(row) }}</mat-cell>
    </ng-container>
    <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
    <mat-row *matRowDef="let row; columns: displayedColumns;"></mat-row>
  </mat-table>
  <br>
</div>

内容的提问来源于stack exchange，提问作者Eren Jaeger