Angular material table with data source: pagination and filter is not working

Question

I have the following angular material table with data source property:

<div class="dim">
  <mat-form-field >
    <input matInput class="warn" (keyup)="applyFilter($event.target.value)" placeholder="Search">
    <mat-icon matSuffix>search</mat-icon>
  </mat-form-field>
</div>
<div class="mat-elevation-z2">
  <table mat-table [dataSource]="dataSource" matSort>
    <ng-container matColumnDef="unit_id">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>ID</th>
      <td class="alignTd" mat-header *matCellDef="let row">{{row.id}}</td>
    </ng-container>

    <ng-container matColumnDef="unit_type">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>Type</th>
      <td mat-header *matCellDef="let row">{{row.unit_type}}</td>
    </ng-container>

    <ng-container matColumnDef="location_id_auto">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>Location</th>
      <td mat-header *matCellDef="let row">{{row.location}}</td>
    </ng-container>

    <ng-container matColumnDef="user_id">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>User</th>
      <td mat-header *matCellDef="let row">{{row.user}}</td>
    </ng-container>

    <ng-container matColumnDef="unit_number_hh">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>Number Of units</th>
      <td mat-header *matCellDef="let row">{{row.unit_number}}</td>
    </ng-container>

    <ng-container matColumnDef="unit_status">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>Status</th>
      <td mat-header *matCellDef="let row">{{row.status}}</td>
    </ng-container>

    <ng-container matColumnDef="unit_date_added">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>Date Added</th>
      <td mat-header *matCellDef="let row">{{row.date_added}}</td>
    </ng-container>
    <tr class="example-expanded-row" mat-header-row *matHeaderRowDef="displayedColumns"></tr>
    <tr mat-row *matRowDef="let row; columns: displayedColumns;">

    </tr>
  </table>
  <mat-paginator [pageSizeOptions]="[5, 10, 25, 100]"></mat-paginator>
</div>

And here is the corresponding typescript for it:

import { Component, OnInit, ViewChild } from '@angular/core';
import { MatTableDataSource, MatPaginator, MatSort } from '@angular/material';
import { HttpClient } from 'selenium-webdriver/http';
import { AuthApiService } from '../../auth-api.service';

@Component({
  selector: 'app-registration',
  templateUrl: './registration.component.html',
  styleUrls: ['./registration.component.css']
})
export class RegistrationComponent implements OnInit {
  dataSource:  any;
  displayedColumns: String[]=['unit_id', 'unit_type', 'location_id_auto', 'user_id', 'unit_number_hh', 'unit_status', 'unit_date_added'];
  @ViewChild(MatPaginator) paginator: MatPaginator;
  @ViewChild(MatSort) sort: MatSort;
  constructor(private auth: AuthApiService) { }

  ngOnInit() {
    this.getUnitData();
    this.dataSource.paginator;
    this.dataSource.sort;
  }

  applyFilter(filterValue: string){
    this.dataSource.filter = filterValue.trim().toLowerCase();

    if(this.dataSource.paginator)
    {
      this.dataSource.paginator.firstPage();
    }
  }

  getUnitData(){
    this.auth.getUnitDataService().subscribe(
      (data)=>
      {
        this.dataSource = Object.values(data);
      },
      (error)=>
      {
        console.log("Error: "+error)
      }
    )

  }

}

I am getting the data and are displayed normally, but I have 6 records, and instead of displaying 5 on the first page and 1 on the other, all 6 rows are displayed on the first page, and the filter is not working at all.

Here is a plunker, you can add an array of data instead.

I have the following error:

ERROR TypeError: Cannot read property 'paginator' of undefined at RegistrationComponent.push../src/app/dashboard/registration/registration.component.ts.RegistrationComponent.ngOnInit (registration.component.ts:20)

Answer 1

Your function getUnitData() is asynchronous and not done in the moment when you access this.dataSource. Change the function to this

getUnitData() {
    this.auth.getUnitDataService().subscribe(
      (data) => {
        this.dataSource = new MatTableDataSource(data);
        this.dataSource.paginator = this.paginator;
        this.dataSource.sort = this.sort;
      },
      (error) => {
        console.log("Error: "+error)
      });
}

also adjust your html

<mat-paginator #paginator [pageSizeOptions]="[5, 10, 25, 100]"></mat-paginator>