如何根据下拉列表中的多项选择过滤结果？

Question

我正在关注 Angular Material 中的材料表示例，目前，他们有一个过滤表示例并输入结果。

我在材料表示例中添加了两个下拉列表，我希望能够从两个下拉列表中选择一个值，并根据这两个下拉列表中的两个值执行搜索。例如。在这种情况下，如果我选择 8 和 Hydrogen，我不应该得到任何结果，因为 8 和hydrogen 不是同一记录/项目的一部分。但是，如果我选择 1 和氢，我应该取回氢，因为 1 和氢值是同一项目/记录的一部分。

这里是 stackbiltz：https://stackblitz.com/edit/angular-t67ae3-huzvd6?file=app%2Ftable-filtering-example.ts

这里是sn-ps的代码：

组件：

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

/**
 * @title Table with filtering
 */
@Component({
  selector: 'table-filtering-example',
  styleUrls: ['table-filtering-example.css'],
  templateUrl: 'table-filtering-example.html',
})
export class TableFilteringExample {
  displayedColumns = ['position', 'name', 'weight', 'symbol'];
  dataSource = new MatTableDataSource(ELEMENT_DATA);

//How do I filter based on selected value? 
  search(selectedValue: string, selectedValueEle: string) {
      selectedValue = selectedValue.trim(); // Remove whitespace
    selectedValue = selectedValue.toLowerCase(); // MatTableDataSource defaults to lowercase matches
     this.dataSource.filter = selectedValue && selectedValueEle;
     debugger 
  }
}

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

const ELEMENT_DATA: Element[] = [
  {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'},
];

html:

<div class="example-container mat-elevation-z8">
  <div class="example-header">

    <select #selectedValueEle>
      <option value="8">8</option>
      <option value="9">9</option>
    </select>
    <select #selectedValue>
      <option value="Hydrogen">Hydrogen</option>
      <option value="Helium">Helium</option>
    </select>
    <button (click)="search(selectedValue.value, selectedValueEle.value)">Search</button>
    <mat-form-field>
      <input matInput (keyup)="applyFilter($event.target.value)" placeholder="Filter">
    </mat-form-field>
  </div>

  <mat-table #table [dataSource]="dataSource">

    <!-- 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;"></mat-row>
  </mat-table>
</div>

Answer 1

如果换行：

this.dataSource.filter = selectedValue && selectedValueEle;

与：

this.dataSource.filter = selectedValueEle + selectedValue;

这应该可以解决问题！

这是因为根据 Angular 表文档https://material.angular.io/components/table/overview#filtering：

例如数据对象{id: 123, name: 'Mr. Smith', favoriteColor: 'blue'} 将减少到 123mr。史密斯布鲁。如果您的过滤器字符串是蓝色的，那么它将被视为匹配，因为它包含在缩减的字符串中，并且该行将显示在表格中。

据我了解，他们正在进行简单的字符串搜索。因此，通过连接值和元素，它对“1Hydrogen”进行字符串搜索，并在缩减的数据对象“1Hydrogen1.0079H”中找到它。

但是您必须按照“1Hydrogen”的顺序使用它，因此通过将selectedValueEle 放在首位，selectedValue 放在后面，您将拥有正确的格式。希望这会有所帮助，祝你好运！