Resetting a form in Angular 2 after submit
I am aware that Angular 2 currently lacks a way to easily reset a form to a pristine state. Poking around I have found a solution like the one below that resets the form fields.
It has been suggested that I need to drop the control group and create a new one to rebuild the form as pristine. I am having difficulty figuring out the best way to do this. I know I need to wrap the form building within a function but I am running into errors when doing that within the constructor.
What would be the best way to rebuild the control group to completely reset the form?
class App {
name: Control;
username: Control;
email: Control;
form: ControlGroup;
constructor(private builder: FormBuilder) {
this.name = new Control('', Validators.required);
this.email = new Control('', Validators.required);
this.username = new Control('', Validators.required);
this.form = builder.group({
name: this.name,
email: this.email,
username: this.username
});
}
onSubmit(value: any): void {
// code that happens when form is submitted
// then reset the form
this.reset();
}
reset() {
for (let name in this.form.controls) {
this.form.controls[name].updateValue('');
this.form.controls[name].setErrors(null);
}
}
}
>= RC.6
Support resetting forms and maintain a submitted state.
console.log(this.form.submitted);
this.form.reset()
or
this.form = new FormGroup()...;
importat update
To set the Form controls to a state when the form is created, like validators, some additional measurements are necessary
In the view part of the form (html) add an *ngIf to show or hide the form
<form *ngIf="showForm"
In the component side of the form (*.ts) do this
showForm:boolean = true;
onSubmit(value:any):void {
this.showForm = false;
setTimeout(() => {
this.reset()
this.showForm = true;
});
}
Here is a more detailed example:
export class CreateParkingComponent implements OnInit {
createParkingForm: FormGroup ;
showForm = true ;
constructor(
private formBuilder: FormBuilder,
private parkingService: ParkingService,
private snackBar: MatSnackBar) {
this.prepareForm() ;
}
prepareForm() {
this.createParkingForm = this.formBuilder.group({
'name': ['', Validators.compose([Validators.required, Validators.minLength(5)])],
'company': ['', Validators.minLength(5)],
'city': ['', Validators.required],
'address': ['', Validators.compose([Validators.required, Validators.minLength(10)])],
'latitude': [''],
'longitude': [''],
'phone': ['', Validators.compose([Validators.required, Validators.minLength(7)])],
'pictureUrl': [''],
// process the 3 input values of the maxCapacity'
'pricingText': ['', Validators.compose([Validators.required, Validators.minLength(10)])],
'ceilingType': ['', Validators.required],
});
}
ngOnInit() {
}
resetForm(form: FormGroup) {
this.prepareForm();
}
createParkingSubmit() {
// Hide the form while the submit is done
this.showForm = false ;
// In this case call the backend and react to the success or fail answer
this.parkingService.create(p).subscribe(
response => {
console.log(response);
this.snackBar.open('Parqueadero creado', 'X', {duration: 3000});
setTimeout(() => {
//reset the form and show it again
this.prepareForm();
this.showForm = true;
});
}
, error => {
console.log(error);
this.showForm = true ;
this.snackBar.open('ERROR: al crear Parqueadero:' + error.message);
}
);
}
}
Plunker example
original <= RC.5 Just move the code that creates the form to a method and call it again after you handled submit:
@Component({
selector: 'form-component',
template: `
<form (ngSubmit)="onSubmit($event)" [ngFormModel]="form">
<input type="test" ngControl="name">
<input type="test" ngControl="email">
<input type="test" ngControl="username">
<button type="submit">submit</button>
</form>
<div>name: {{name.value}}</div>
<div>email: {{email.value}}</div>
<div>username: {{username.value}}</div>
`
})
class FormComponent {
name:Control;
username:Control;
email:Control;
form:ControlGroup;
constructor(private builder:FormBuilder) {
this.createForm();
}
createForm() {
this.name = new Control('', Validators.required);
this.email = new Control('', Validators.required);
this.username = new Control('', Validators.required);
this.form = this.builder.group({
name: this.name,
email: this.email,
username: this.username
});
}
onSubmit(value:any):void {
// code that happens when form is submitted
// then reset the form
this.reset();
}
reset() {
this.createForm();
}
}
Plunker example
Use NgForm's .resetForm() rather than .reset() because it is the method that is officially documented in NgForm's public api. (Ref [1])
<form (ngSubmit)="mySubmitHandler(); myNgForm.resetForm()" #myNgForm="ngForm">
The .resetForm() method will reset the NgForm's FormGroup and set it's submit flag to false (See [2]).
Tested in @angular versions 2.4.8 and 4.0.0-rc3
For Angular 2 Final, we now have a new API that cleanly resets the form:
@Component({...})
class App {
form: FormGroup;
...
reset() {
this.form.reset();
}
}
This API not only resets the form values, but also sets the form field states back to ng-pristine and ng-untouched.
If you call only reset() function, the form controls will not set to pristine state. android.io docs have a solution for this issue.
component.ts
active = true;
resetForm() {
this.form.reset();
this.active = false;
setTimeout(() => this.active = true, 0);
}
component.html
<form *ngIf="active">
When I was going through the Angular basics guide on forms, and hit the resetting of forms section, I was very much left in surprise when I read the following in regards to the solution they give.
This is a temporary workaround while we await a proper form reset feature.
I personally haven't tested if the workaround they provided works (i assume it does), but I believe it is not neat, and that there must be a better way to go about the issue.
According to the FormGroup API (which is marked as stable) there already is a 'reset' method.
I tried the following. In my template.html file i had
<form (ngSubmit)="register(); registrationForm.reset();" #registrationForm="ngForm">
...
</form>
Notice that in the form element, I've initialised a template reference variable 'registrationForm' and initialized it to the ngForm Directive, which "governs the form as a whole". This gave me access to the methods and attributes of the governing FormGroup, including the reset() method.
Binding this method call to the ngSubmit event as show above reset the form (including pristine, dirty, model states etc) after the register() method is completed. For a demo this is ok, however it isn't very helpful for real world applications.
Imagine the register() method performs a call to the server. We want to reset the form when we know that the server responded back that everything is OK. Updating the code to the following caters for this scenario.
In my template.html file :
<form (ngSubmit)="register(registrationForm);" #registrationForm="ngForm">
...
</form>
And in my component.ts file :
@Component({
...
})
export class RegistrationComponent {
register(form: FormGroup) {
...
// Somewhere within the asynchronous call resolve function
form.reset();
}
}
Passing the 'registrationForm' reference to the method would allow us to call the reset method at the point of execution that we want to.
Hope this helps you in any way. :)
Note: This approach is based on Angular 2.0.0-rc.5