FormArray inside Angular Material Table

Question

Note: I succeded doing FormArray inside classic HTML Table, as seen below . I want to have a FormArray inside Angular Material table and to populate it with data. I tried the same approach as with classic HTML Table, but i was not able to compile it due error "Could not find column with id 'name''"

<div class="form-group">
<form [formGroup]="myForm" role="form">
  <div formArrayName="formArrList">
    <table>
      <tr>
        <th>Name</th>
        <th>School</th>

      </tr>

      <tr *ngFor="let list of myForm.get('formArrList').controls;let i = index" [formGroupName]="i">
        <td>
          <div class="col-sm-6">
            <input class="form-control" type="text"  formControlName="name"/>
          </div>
        </td>
        <td>
          <div class="col-sm-6">
            <input class="form-control" type="text"  formControlName="school"/>
          </div>
        </td>
      </tr>
    </table>
  </div>
</form>

I try to have a FormArray inside my Angular Material Table Here is my HTML file

<div>
<form [formGroup]="myForm" role="form">
  <ng-container formArrayName="formArrList">

  <mat-table #table [dataSource]="myDataSource">
    <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
    <mat-row *matRowDef="let row; columns: displayedColumns;"></mat-row>


    <ng-container *ngFor="let detailsItems of myForm.get('formArrList').controls;let i = index" [formGroupName]="i">


    <ng-container matColumnDef="name">
      <mat-header-cell *matHeaderCellDef>Name</mat-header-cell>
      <mat-cell *matCellDef="let element"> 

        <mat-form-field class="" hideRequiredMarker>
      <input matInput formControlName="name" type="text" class="form-control"
             autocomplete="off"
             placeholder="name">
      </mat-form-field>

      </mat-cell>
    </ng-container>



    <ng-container matColumnDef="school">
      <mat-header-cell *matHeaderCellDef>School</mat-header-cell>
      <mat-cell *matCellDef="let element"> 

       <mat-form-field class="" hideRequiredMarker>
      <input matInput formControlName="school" type="text" class="form-control"
             autocomplete="off"
             placeholder="school">
      </mat-form-field>
      </mat-cell>
    </ng-container>

    </ng-container>



  </mat-table>
  </ng-container>

</form>

And here is a part of my .TS file

@Component(..)
export class DemO implements OnInit {

 displayedColumns = ['name', 'school'];
  myForm: FormGroup;

  formArrList: FormArray;

   myDataSource: DataSource;
   dummyData: Element[] = [];


   ngOnInit(): void {

    //init form arrayTree
    this.myForm = this.formBuilder.group({
      'formArrList': new FormArray([])
    });

  }

    initTreeFormArray(name: string, school: string) {
    return this.formBuilder.group({
      'name': [code_any,],
      'school': [prio,]
    });
  }


  renderTableOnButtonClick(){
       const control = <FormArray>this.treeForm.controls['formArrList']; 
       control.push(this.initTreeFormArray("DummyName", "DummySchool", element.name));



      this.dummyData.push({name: "DummyName", school: "DummySchool"});
      this.myDataSource = new sDataSource(this.dummyData);


}

Answer 1

A little late to the party but I managed to get it working.

https://stackblitz.com/edit/angular-material-table-with-form-59imvq

Component

import {
  Component, ElementRef, OnInit
} from '@angular/core';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators'
import { AlbumService } from './album.service';
import { UserService } from './user.service';
import { Album } from './album.model';
import { User } from './user.model';
import { FormArray, FormGroup, FormBuilder } from '@angular/forms';
import { MatTableDataSource } from '@angular/material';

@Component({
  selector: 'table-form-app',
  templateUrl: 'app.component.html'
})
export class AppComponent implements OnInit {
  form: FormGroup;
  users: User[] = [];
  dataSource: MatTableDataSource<any>;
  displayedColumns = ['id', 'userId', 'title']
  constructor(
    private _albumService: AlbumService,
    private _userService: UserService,
    private _formBuilder: FormBuilder
    ) {}

  ngOnInit() {
    this.form = this._formBuilder.group({
      albums: this._formBuilder.array([])
    });
    this._albumService.getAllAsFormArray().subscribe(albums => {
      this.form.setControl('albums', albums);
      this.dataSource = new MatTableDataSource((this.form.get('albums') as FormArray).controls);
      this.dataSource.filterPredicate = (data: FormGroup, filter: string) => { 
          return Object.values(data.controls).some(x => x.value == filter); 
        };
    });
    this._userService.getAll().subscribe(users => {
      this.users = users;
    })
  }

  get albums(): FormArray {
    return this.form.get('albums') as FormArray;
  }

  // On user change I clear the title of that album 
  onUserChange(event, album: FormGroup) {
    const title = album.get('title');

    title.setValue(null);
    title.markAsUntouched();
    // Notice the ngIf at the title cell definition. The user with id 3 can't set the title of the albums
  }

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

HTML

<mat-form-field>
  <input matInput (keyup)="applyFilter($event.target.value)" placeholder="Filter">
</mat-form-field>

<form [formGroup]="form" autocomplete="off">
    <mat-table [dataSource]="dataSource">

      <!--- Note that these columns can be defined in any order.
            The actual rendered columns are set as a property on the row definition" -->

      <!-- Id Column -->
      <ng-container matColumnDef="id">
        <mat-header-cell *matHeaderCellDef> Id </mat-header-cell>
        <mat-cell *matCellDef="let element"> {{element.get('id').value}}. </mat-cell>
      </ng-container>

      <!-- User Column -->
      <ng-container matColumnDef="userId">
        <mat-header-cell *matHeaderCellDef> User </mat-header-cell>
        <mat-cell *matCellDef="let element" [formGroup]="element">
          <mat-form-field floatLabel="never">
            <mat-select formControlName="userId" (selectionChange)="onUserChange($event, element)" required>
              <mat-option *ngFor="let user of users" [value]="user.id">
                {{ user.username }}
              </mat-option>
            </mat-select>
          </mat-form-field>
        </mat-cell>
      </ng-container>

      <!-- Title Column -->
      <ng-container matColumnDef="title">
        <mat-header-cell *matHeaderCellDef> Title </mat-header-cell>
        <mat-cell *matCellDef="let element;" [formGroup]="element">
          <mat-form-field floatLabel="never" *ngIf="element.get('userId').value !== 3">
            <input matInput placeholder="Title" formControlName="title" required>
          </mat-form-field>
        </mat-cell>
      </ng-container>

      <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
      <mat-row *matRowDef="let row; columns: displayedColumns;"></mat-row>
    </mat-table>
</form>
<mat-accordion>
  <mat-expansion-panel>
    <mat-expansion-panel-header>
      <mat-panel-title>
        Form value
      </mat-panel-title>
    </mat-expansion-panel-header>
    <code>
      {{form.value | json}}
    </code>
  </mat-expansion-panel>
</mat-accordion>

Answer 2

initTreeFormArray() does not fire on init the way you need it to. So when the component is built, the html portion is looking for name, when it does not exist.

My .02 is to load a working form and subform groups on init and figure out the second function later. Also, use Mat over html table.

Answer 3

Probably you don't need controls here

myForm.get('formArrList').controls

try to use

myForm.controls.formArrList.controls

or

myForm.get('formArrList')

Answer 4

In Angular 9, to make Material Table use FormArray as dataSource.

I created the interface to define the type of MatTableDataSource<Type> and also created the form of corresponding fields of that interface. Then, When you need to initialize the data source, you can allocate the form array value. I used getter for Form Array and then I called that like: this.myGetter.value.

Below is the code:

Declaration

dataSource = new MatTableDataSource<MyInterface>();

Initialization Method

// I call this method whenever a change occur in FormArray
initializeMyDataSource() {
    this.dataSource = new MatTableDataSource<MyInterface>(this.myGetter.value);
}

My Getter

get myGetter(): FormArray {
    return (this.myFormGroup.get('myFormArray') as FormArray);
  }

My Interface

export interface MyInterface {
  fieldA: string;
  fieldB: number;
}

My FormGroup

this.formBuilder.group({
  fieldA: [''],
  fieldB: ['']
})

In the HTML, just use dataSource as you normally would for MatTable. Basically, when you use .value at the end of formGroup or formArray, it returns a normal object which, in this case, would be MyInterface object which is also the type of this MatTable.

Here you can follow the matTable guidelines. Make sure to check it with dummy data first before you apply formArray, to ensure where the error is coming from.

Hope that helps!