Angular 4 Form FormArray Add a Button to add or delete a form input row - forms

Question

I am building an app using Angular 4.0.2. How can I add a button to a form to add a new row of input and a delete button for a particular row to delete? I mean that I want a form something like this. I want my form to look something like this:
.
Here is my code:
add-invoice.component.html
<h3 class="page-header">Add Invoice</h3>
<form [formGroup]="invoiceForm">
<div formArrayName="itemRows">
<div *ngFor="let itemrow of itemRows.controls; let i=index" [formGroupName]="i">
<h4>Invoice Row #{{ i + 1 }}</h4>
<div class="form-group">
<label>Item Name</label>
<input formControlName="itemname" class="form-control">
</div>
<div class="form-group">
<label>Quantity</label>
<input formControlName="itemqty" class="form-control">
</div>
<div class="form-group">
<label>Unit Cost</label>
<input formControlName="itemrate" class="form-control">
</div>
<div class="form-group">
<label>Tax</label>
<input formControlName="itemtax" class="form-control">
</div>
<div class="form-group">
<label>Amount</label>
<input formControlName="amount" class="form-control">
</div>
<button *ngIf="i > 1" (click)="deleteRow(i)" class="btn btn-danger">Delete Button</button>
</div>
</div>
<button type="button" (click)="addNewRow()" class="btn btn-primary">Add new Row</button>
</form>
<p>{{invoiceForm.value | json}}</p>
Here is my code for add-invoice.component.ts
import { Component, OnInit } from '#angular/core';
import { FormBuilder, FormControl, FormArray, FormGroup } from '#angular/forms';
#Component({
selector: 'app-add-invoice',
templateUrl: './add-invoice.component.html',
styleUrls: ['./add-invoice.component.css']
})
export class AddInvoiceComponent implements OnInit {
invoiceForm: FormGroup;
constructor(
private _fb: FormBuilder
) {
this.createForm();
}
createForm(){
this.invoiceForm = this._fb.group({
itemRows: this._fb.array([])
});
this.invoiceForm.setControl('itemRows', this._fb.array([]));
}
get itemRows(): FormArray {
return this.invoiceForm.get('itemRows') as FormArray;
}
addNewRow(){
this.itemRows.push(this._fb.group(itemrow));
}
ngOnInit(){
}
}

Answer 1

Here's a shortened version of your code:
When you init your form, you can add one empty formgroup inside your formArray:
ngOnInit() {
this.invoiceForm = this._fb.group({
itemRows: this._fb.array([this.initItemRows()])
});
}
get formArr() {
return this.invoiceForm.get('itemRows') as FormArray;
}
Then the function:
initItemRows() {
return this._fb.group({
// list all your form controls here, which belongs to your form array
itemname: ['']
});
}
Here is the addNewRow and deleteRow functions:
addNewRow() {
this.formArr.push(this.initItemRows());
}
deleteRow(index: number) {
this.formArr.removeAt(index);
}
Your form should look like this:
<form [formGroup]="invoiceForm">
<div formArrayName="itemRows">
<div *ngFor="let itemrow of formArr.controls; let i=index" [formGroupName]="i">
<h4>Invoice Row #{{ i + 1 }}</h4>
<div>
<label>Item Name</label>
<input formControlName="itemname">
</div>
<button type="button" (click)="deleteRow(i)" *ngIf="formArr.controls.length > 1" >
Delete
</button>
</div>
</div>
<button type="button" (click)="addNewRow()">Add new Row</button>
</form>
Here's a
DEMO