If I tab through the text inputs without entering anything, the error msg divs display indicating that the required validator has fired correctly. However, if I type anything into one of the fields, the console immediately throws this error:
Cannot read property 'required' of null
Here is my component:
import { PasswordValidators } from './../validators/password.validators';
import { Component, OnInit } from '@angular/core';
import { FormBuilder, Validators, FormGroup, FormControl } from '@angular/forms';
@Component({
selector: 'app-changepassword-form',
templateUrl: './changepassword-form.component.html',
styleUrls: ['./changepassword-form.component.css']
})
export class ChangepasswordFormComponent {
form;
constructor(fb: FormBuilder) {
this.form = fb.group({
newPassword: ['', Validators.required],
confirmPassword: ['', Validators.required]
})
}
get newPassword() {
return this.form.get('newPassword');
}
get confirmPassword() {
return this.form.get('confirmPassword');
}
}
and HTML:
<form [formGroup]="form">
<div class="form-group">
<label for="newPassword">New Password</label>
<input formControlName="newPassword" id="newPassword" type="text" class="form-control">
<div class="alert alert-danger" *ngIf="newPassword.touched && newPassword.errors.required">
Required
</div>
</div>
<div class="form-group">
<label for="confirmPassword">Confirm Password</label>
<input formControlName="confirmPassword" id="confirmPassword" type="text" class="form-control">
<div class="alert alert-danger" *ngIf="confirmPassword.touched && confirmPassword.errors.required">
Required
</div>
</div>
<p><button class="btn btn-primary">Submit</button></p>
</form>
reset()linkResets the form control, marking it pristine and untouched , and resetting the value. The new value will be the provided value (if passed), null , or the initial value if nonNullable was set in the constructor via FormControlOptions .
Both FormControls and FormGroups expose an observable called valuesChanged . By subscribing to this observable we can react in real-time to changing values of an individual form control, or a group of form controls.
That error is coming from this:
*ngIf="newPassword.touched && newPassword.errors.required"
When you put in a value, there is no longer an errors collection so checking newPassword.errors.required
generates that Cannot read property 'required' of null
error.
Try something like this instead:
*ngIf="newPassword.touched && newPassword.errors?.required"
As an example, mine looks like this:
<div class="col-md-8">
<input class="form-control"
id="productNameId"
type="text"
placeholder="Name (required)"
required
minlength="3"
[(ngModel)] = product.productName
name="productName"
#productNameVar="ngModel" />
<span class="help-block" *ngIf="(productNameVar.touched ||
productNameVar.dirty || product.id !== 0) &&
productNameVar.errors">
<span *ngIf="productNameVar.errors.required">
Product name is required.
</span>
<span *ngIf="productNameVar.errors.minlength">
Product name must be at least three characters.
</span>
</span>
</div>
You can also use the following syntax and it will work without the need to have a value first:
form.get('newPassword').hasError('required')
This will check for 'required' in the errors.
This will work as well and it's more concise :
form.hasError('required','newPassword')
If you are compiling with AOT option, according to this article, you should privilege hasError() syntax:
Don’t use control.errors?.someError, use control.hasError(‘someError’)
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With