Add a row dynamically : Angular Reactive-Form

Question

I want to add row dynamically when I click the button. I'm using reactive-form for this.

here is my html code

<table>
    <thead>
        <tr class='tableHeader'>
            <div fxLayout="row" fxLayoutAlign="start center" fxFlex="1 0 auto">
                <td fxFlex="22" class="pr-4">Name</td>
                <td fxFlex="15" class="pr-4">Price</td>
                <td fxFlex="15" class="pr-4">Loan Term</td>
                <td fxFlex="15" class="pr-4">Quantity</td>
                <td fxFlex="15" class="pr-4">Deposit</td>
                <td fxFlex="15" class="pr-4">Total</td>
            </div>
        </tr>
    </thead>
    <tbody>
        <tr [formGroup]="loanProductForm">
            <div fxLayout="row" fxLayoutAlign="start center" fxFlex="1 0 auto">
                <td fxFlex="22">
                    <mat-form-field appearance="outline" fxFlex="100" class="pr-4">
                        <mat-label>Product </mat-label>
                        <mat-select formControlName="productId" required>
                            <mat-option *ngFor="let product of productList" [value]="product.productId">
                                {{product.name}}
                            </mat-option>
                        </mat-select>
                    </mat-form-field>
                </td>
                <td fxFlex="15">
                    <mat-form-field appearance="outline" fxFlex="100" class="pr-4">
                        <mat-label>Price </mat-label>
                        <input type='number' matInput formControlName="price" name="" id="" placeholder="Price" required>
                    </mat-form-field>
                </td>
                <td fxFlex="15">
                    <mat-form-field appearance="outline" fxFlex="100" class="pr-4">
                        <mat-label>Loan Term </mat-label>
                        <mat-select formControlName="loanTermId" required>
                            <mat-option *ngFor="let loanTerm of loanTermList" [value]="loanTerm.loanTermId">
                                {{loanTerm.numberOfMonths}}
                            </mat-option>
                        </mat-select>
                    </mat-form-field>
                </td>
                <td fxFlex="15">
                    <mat-form-field appearance="outline" fxFlex="100" class="pr-4">
                        <mat-label>Quantity </mat-label>
                        <input type='number' formControlName="quantity" matInput name="" id="" placeholder="Quantity" required>
                    </mat-form-field>
                </td>
                <td fxFlex="15">
                    <mat-form-field appearance="outline" fxFlex="100" class="pr-4">
                        <mat-label>Deposit </mat-label>
                        <input type='number' formControlName="deposit" matInput name="" id="" placeholder="Deposit" required>
                    </mat-form-field>
                </td>
                <td fxFlex="15">
                    <mat-form-field appearance="outline" fxFlex="100" class="pr-4">
                        <mat-label>Total </mat-label>
                        <input type='number' formControlName="total" matInput name="" id="" placeholder="Total" required>
                    </mat-form-field>
                </td>

            </div>
        </tr>
        <tr>
            <td fxFlex="10">
                <div fxLayout="row" fxLayoutAlign="start center" fxFlex="1 0 auto">
                    <button mat-stroked-button class='addBtn btn-style-2' fxFlex='100' (click)='addTableRow()'>Add
                        <mat-icon matSuffix>add_box</mat-icon>
                    </button>
                </div>
            </td>
        </tr>
    </tbody>
</table>

and here is how I'm trying in my ts file

   this.loanProductForm = this._formBuilder.group({
      productId: ['', Validators.required],
      price: ['', Validators.required],
      loanTermId: ['', Validators.required],
      quantity: ['', Validators.required],
      deposit: ['', Validators.required],
      total: ['', Validators.required],
    })


addTableRow() {
    this.newRow = { productId: '', price: '', loanTermId: '', quantity: '', deposit: '', total: '' };
    // this.tableRows.push(this.newRow)
  }

but the code won't let me use push method on this form

Answer 1

You need to use Form Array in this case.

Try like this:

Working Demo

.ts

this.loanProductForm = this.fb.group({
  products: this.fb.array([
    this.addProductFormGroup()
  ])
});

 addProductFormGroup(): FormGroup {
    return this.fb.group({
      productId: ['', Validators.required],
      price: ['', Validators.required],
      loanTermId: ['', Validators.required],
      quantity: ['', Validators.required],
      deposit: ['', Validators.required],
      total: ['', Validators.required],
    });
  }

addProductButtonClick(): void {
   (<FormArray>this.loanProductForm.get('products')).push(this.addProductFormGroup());
}

.html

 <button type="button" (click)="addProductButtonClick()">
          Add Product
 </button>