angular - Material table datasource filter with column value

Question

How can I filter the material data table with specific column ?

public dataSource;


this.dataSource = new MatTableDataSource(this.items);
        this.dataSource.filterPredicate = function customFilter(data , filter:string ): boolean {
            return (data.name.startsWith(filter));
        }

applyFilter(filterValue: string) {
    filterValue = filterValue.trim(); // Remove whitespace
    filterValue = filterValue.toLowerCase(); // MatTableDataSource defaults to lowercase matches
    this.dataSource.filter = filterValue;
}

---

The above code is not working, when I type returns as no data is matched.

Answer 1

From the docs.

For example, the data object {id: 123, name: 'Mr. Smith', favoriteColor: 'blue'} will be reduced to 123mr. smithblue. If your filter string was blue then it would be considered a match because it is contained in the reduced string, and the row would be displayed in the table.

To override the default filtering behavior, a custom filterPredicate function can be set which takes a data object and filter string and returns true if the data object is considered a match.

If you want to use filter only specific columns you need to override filterPredicate and the answer already is here.

This is the working example for filtering.

table-filtering-example.html

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

table-filtering-example.ts

  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);

      applyFilter(filterValue: string) {
        filterValue = filterValue.trim(); // Remove whitespace
        filterValue = filterValue.toLowerCase(); // MatTableDataSource defaults to lowercase matches
        this.dataSource.filter = filterValue;
      }
    }

    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'}, ];

---

you can use filterPredicate to filter specific column like this:

  ngOnInit() {
    this.dataSource.filterPredicate = (data: Element, filter: string) => {
      return data.name == filter;
     };
   }
 applyFilter(filterValue: string) {
    // filterValue = filterValue.trim(); // Remove whitespace
    // filterValue = filterValue.toLowerCase(); // MatTableDataSource defaults to lowercase matches
    this.dataSource.filter = filterValue;
  }

I have changed the applyFilter() and added ngOnInit(). Now it is working only name column and exactly same value (==)