Angular matSort does not sort

Issue

I’m having trouble with importing matSort into my matTable.

I’m providing you with my code:

dashboard.component.ts

import {Component, ViewChild} from '@angular/core';
import {UserService} from "../user.service";
import {DohvatMantisaService} from "../dohvat-mantisa.service";
import {Mantisi} from "../Mantisi";
import {Observable} from "rxjs/Observable";
import {DataSource} from "@angular/cdk/collections";
import 'rxjs/add/observable/of';
import 'rxjs/add/operator/startWith';
import 'rxjs/add/observable/merge';
import {MatSort} from '@angular/material';
@Component({
  selector: 'app-dashboard',
  templateUrl: './dashboard.component.html',
  styleUrls: ['./dashboard.component.css']
})
export class DashboardComponent{
  displayedColumns = ['projekt', 'manits', 'kategorija','ozbiljnost','datum_prijave','postavio','odjel','postavio','naziv','status','planirana_isporuka'];
  constructor(private user:UserService, private dohvatMantisa:DohvatMantisaService) {
  }
  dataSource: TableDataSource | null;
  mantisi: Mantisi[];
  name = this.user.getUsername();
  @ViewChild(MatSort) sort: MatSort;
  ngOnInit() {
    this.dataSource = new TableDataSource(this.dohvatMantisa,this.sort);
  }
}

export class TableDataSource extends DataSource<Mantisi>{
  constructor(private mantisiDS: DohvatMantisaService,private sort: MatSort){
    super();
  }
  connect(): Observable<Mantisi[]> {
    const displayDataChanges = [
      this.mantisiDS.dohvatiMantise(),
      this.sort.sortChange,
    ];

    return Observable.merge(...displayDataChanges).map(() => {
      return this.getSortedData();
    });
  }
  disconnect() {}

  getSortedData(): Mantisi[]{
    const data = this.mantisiDS.prikazMantisa().slice();
    if (!this.sort.active || this.sort.direction == '') { return data; }
    return data.sort((a, b) => {
      let propertyA: number|string = '';
      let propertyB: number|string = '';
      switch (this.sort.active) {
        case 'projekt': [propertyA, propertyB] = [a.projekt, b.projekt]; break;
        case 'manits': [propertyA, propertyB] = [a.manits, b.manits]; break;
        case 'kategorija': [propertyA, propertyB] = [a.kategorija, b.kategorija]; break;
        case 'ozbiljnost': [propertyA, propertyB] = [a.ozbiljnost, b.ozbiljnost]; break;
        case 'datum_prijave': [propertyA, propertyB] = [a.datum_prijave, b.datum_prijave]; break;
        case 'postavio': [propertyA, propertyB] = [a.postavio, b.postavio]; break;
        case 'naziv': [propertyA, propertyB] = [a.naziv, b.naziv]; break;
        case 'status': [propertyA, propertyB] = [a.status, b.status]; break;
        case 'planirana_isporuka': [propertyA, propertyB] = [a.planirana_isporuka, b.planirana_isporuka]; break;
      }

      let valueA = isNaN(+propertyA) ? propertyA : +propertyA;
      let valueB = isNaN(+propertyB) ? propertyB : +propertyB;

      return (valueA < valueB ? -1 : 1) * (this.sort.direction == 'asc' ? 1 : -1);
    });
  }
}

This is my service:
dohvatMantisaService

import { Injectable } from '@angular/core';
import {Http, Response, RequestOptions, Headers} from "@angular/http";
import {Observable} from "rxjs/Observable";
import {Mantisi} from "./Mantisi";
import 'rxjs';
import 'rxjs/operator/map';
import 'rxjs/operator/do';

@Injectable()
export class DohvatMantisaService {
  constructor(public http:Http) { }
  result: Mantisi[];
  dohvatiMantise(): Observable<Mantisi[]>{
    return this.http.get('/mantis/getMantisReport').map(this.extractData);
  }
  private extractData(response: Response) {
    let body = response.json();
    return body || {};
  }

  prikazMantisa(): Mantisi[]{
    this.dohvatiMantise().subscribe(res => this.result = res);
    return this.result;
  }
}

And im providing you with my dashboard.component.html matSort row:

<mat-table #table [dataSource]="dataSource" class="example-table" matSort>

The main problem here is that data is loaded and acquired from http request but I’m getting errors in console something like this:

Cannot read property ‘sortChange’ of undefined
at TableDataSource.webpackJsonp…/../../../../src/app/dashboard/dashboard.component.ts.TableDataSource.connect (dashboard.component.ts:36)
at MatTable.webpackJsonp…/../../cdk/esm5/table.es5.js.CdkTable._observeRenderChanges (table.es5.js:602)
at MatTable.webpackJsonp…/../../cdk/esm5/table.es5.js.CdkTable.ngAfterContentChecked (table.es5.js:522)

It tells me that this.sort.sortChange is undefined.
I searched all bit of internet and couldn’t find proper answer. Hope you can help me with that.

Solution

I’ve found solution for this problem.

The main problem was that table was rendered before data arrived. I’ve loaded data first and sent it like source to dataSource constructor. After it, problem disappeared. That’s the thing with async http.get and services.

Thanks for you help.

fetchData(id){
  this.fetch.getProcesses(id).subscribe(result => {
    this.processes = result;
    this.dataSource = new TableDataSource(this.processes);
    Observable.fromEvent(this.filter.nativeElement, 'keyup')
      .debounceTime(150)
      .distinctUntilChanged()
      .subscribe(() => {
        if (!this.dataSource) {
          return;
        }
        this.dataSource.filter = this.filter.nativeElement.value;
      });
  });
}




export class TableDataSource extends DataSource<Proces>{
  _filterChange = new BehaviorSubject('');
  get filter(): string {
    return this._filterChange.value;
  }
  set filter(filter: string) {
    this._filterChange.next(filter);
  }
  filteredData: any =[];

  constructor(private processes:Proces[]){
    super();
  }
  connect(): Observable<Proces[]>{
    const displayDataChanges = [
      this.processes,
      this._filterChange,
    ];
    return Observable.merge(...displayDataChanges).map(() => {
      this.filteredData = this.processes.slice().filter((item: Proces) => {
        const searchStr = (item.name).toLowerCase();
        return searchStr.indexOf(this.filter.toLowerCase()) !== -1;

      });
      return this.filteredData;
    })
  }
  disconnect(){}
}



      <div class="header">
    <mat-form-field floatPlaceholder="never">
      <input matInput #filter placeholder="PretraĹži procese">
    </mat-form-field>
  </div>
  <mat-table #table [dataSource]="dataSource" class="table-mantis" matSort>

    <ng-container matColumnDef="col1">
      <mat-header-cell *matHeaderCellDef class="table-header-cell" mat-sort-header> Name</mat-header-cell>
      <mat-cell *matCellDef="let row" class="example-cell" > {{row.nazivProcesa}} </mat-cell>
    </ng-container>

    <ng-container matColumnDef="col2">
      <mat-header-cell *matHeaderCellDef class="table-header-cell" mat-sort-header> Cell 2</mat-header-cell>
      <mat-cell *matCellDef="let row" class="example-cell" > {{row.nazivVlasnika
        }} </mat-cell>
    </ng-container>

    <ng-container matColumnDef="col3">
      <mat-header-cell *matHeaderCellDef class="table-header-cell" mat-sort-header> Cell 3</mat-header-cell>
      <mat-cell *matCellDef="let row" class="example-cell" > {{row.interniAkt}} </mat-cell>
    </ng-container>

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

Answered By – Vinko Vorih

Answer Checked By – Robin (AngularFixing Admin)

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