Guide to activating a button with reactive forms in angular 2

Question

Guide to activating a button with reactive forms in angular 2

I am facing an issue where I have an input field and a button. The button should be enabled when the field is not empty. However, even though I am already passing an input value, the button is not being enabled as expected. It only gets enabled when I actually type something in the input field. Does anyone have any advice on how to resolve this? Below is the code snippet:

export class SignupFormComponent implements OnInit {
  userForm: FormGroup;
  submitted: boolean;
  hello = "hello world";

  ngOnInit() {
    this.userForm = new FormGroup({
      firstName: new FormControl('',[<any>Validators.required, <any>Validators.minLength(5)])
    });
  }

  onSubmit({ value, valid }: { value: userForm, valid: boolean }) {
    this.submitted = true;
    console.log(value,valid);
  }
}

Here is my HTML code:

<form [formGroup]="userForm" (ngSubmit)="onSubmit(userForm)" validate>
  <div class="form-group">
    <label>First Name</label>
    <input type="text" class="form-control" formControlName="firstName" [value]="hello">
  </div>
  <button type="submit"  class="btn btn-primary" [disabled]="userForm.invalid">Submit </button>
</form>

angular typescript primeng

Answer 1

Answer №1

To properly set up your reactive form, it is important to remove the [value]="hello" from the input field and instead include it in the

new FormControl(value, [validators], [asyncValidators])

.

Here's an example of how you can do this:

ngOnInit() {
  this.userForm = new FormGroup({
    firstName: new FormControl(this.hello, [<any>Validators.required, <any>Validators.minLength(5)])
  });
}

Answer 2

To properly set up your reactive form, it is important to remove the [value]="hello" from the input field and instead include it in the

new FormControl(value, [validators], [asyncValidators])

.

Here's an example of how you can do this:

ngOnInit() {
  this.userForm = new FormGroup({
    firstName: new FormControl(this.hello, [<any>Validators.required, <any>Validators.minLength(5)])
  });
}

Answer 3

Answer №2

To make things simpler, you can utilize reactive forms in the following manner:

step1: Start by importing ReactiveForm, FormBuilder, Validators
step2: Create a FormGroup object and inject form builder into the constructor
step3: Initialize your form group
step4: Implement the reactive form just like before but with some modifications

Code:

export class RegistrationComponent implements OnInit {
  userForm: FormGroup;
  firstName: string;

  constructor(private _formBuilder:FormBuilder){}

  ngOnInit() {
    this.userForm = this._formBuilder.group({
      'firstName': ['',[Validators.required,Validators.minLength(5)]]
    });
  }

  onSubmit() {
    console.log(this.firstName);
  }
}

HTML:

<form [formGroup]="userForm" (ngSubmit)="onSubmit()" name="userForm">
      <div class="form-group">
        <label>First Name</label>
        <input type="text" [(ngModel)]="firstName" class="form-control" formControlName="firstName">
        <p *ngIf="userForm.controls.firstName.invalid && (userForm.controls.firstName.dirty || userForm.controls.firstName.touched)"> Error message </p>
      </div>
      <button type="submit"  class="btn btn-primary" [disabled]="userForm.invalid">Submit </button>
    </form>

Answer 4

To make things simpler, you can utilize reactive forms in the following manner:

step1: Start by importing ReactiveForm, FormBuilder, Validators
step2: Create a FormGroup object and inject form builder into the constructor
step3: Initialize your form group
step4: Implement the reactive form just like before but with some modifications

Code:

export class RegistrationComponent implements OnInit {
  userForm: FormGroup;
  firstName: string;

  constructor(private _formBuilder:FormBuilder){}

  ngOnInit() {
    this.userForm = this._formBuilder.group({
      'firstName': ['',[Validators.required,Validators.minLength(5)]]
    });
  }

  onSubmit() {
    console.log(this.firstName);
  }
}

HTML:

<form [formGroup]="userForm" (ngSubmit)="onSubmit()" name="userForm">
      <div class="form-group">
        <label>First Name</label>
        <input type="text" [(ngModel)]="firstName" class="form-control" formControlName="firstName">
        <p *ngIf="userForm.controls.firstName.invalid && (userForm.controls.firstName.dirty || userForm.controls.firstName.touched)"> Error message </p>
      </div>
      <button type="submit"  class="btn btn-primary" [disabled]="userForm.invalid">Submit </button>
    </form>

Guide to activating a button with reactive forms in angular 2

Answer №1

Answer №2

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