CODEWITHSUNDEEP
angular
Prajwal
Prajwal

Reputation: 673

Angular template driven form not performing min validation

I have angular 11 template driven form with this input

<form #currentForm="ngForm">
<input matInput type="number" min="18" placeholder="Your age" name="age" [(ngModel)]="memberDetailForm.age">
</form>

{{ currentForm.controls.age?.errors | json }}
{{ currentForm.valid }}

Here form is not performing min validation check, even if I enter 15 which is less than 18, I see no errors and form shows valid. However if I change the input type to text and have some other check like minLenth="5" and enter 4 chars, the error shows up and forms become invalid.

Can anybody help me understand this strange behavior?

Upvotes: 0

Views: 1682

Answers (1)

Masoud Bimar
Masoud Bimar

Reputation: 7821

Displaying the Validation/Error messages

We need to provide a short and meaningful error message to the user.

Angular creates a FormControl for each and every field, which has ngModel directive applied. The FormControl exposes the state of form elements like valid, dirty, touched, etc.

There are two ways in which you can get the reference to the FormControl.

One way is to use the currentForm variable. We can use the currentForm.controls.age.valid to find out if the age is valid.

The other way is to create a new local variable for each FormControl For Example, the following age="ngModel" creates the age variable with the FormControl instance.

<input type="text" id="age" name="age" required minlength="10" 
            #age="ngModel" [(ngModel)]="contact.age">

Now, we have a reference to the age FormControl instance, we can check its status. We use the valid property to check if the age has any errors.

valid: returns either invalid status or null which means a valid status

<div *ngIf="!age?.valid && (age?.dirty || age?.touched)">
   Invalid Age Or Required
</div>

For Complete Sample check here.

To apply min/max validation on a number you will need to create a Custom Validator

Check this Answer to see the Implementation.

Update:

Angular v12 is now available & Support From the Community

The Angular community has been hard at work improving the Angular experience for everyone by contributing to the framework — thank you!

Here are some of the PRs that have been landed thanks to your incredible work:

  • Avoid ngZone from throwing a navigation-related warning unnecessarily (#25839)
  • HttpClient supports specifying request metadata (#25751)
  • min and max Forms validators added (#39063)
  • Support APP_INITIALIZER work with observables (#33222)

Upvotes: 1

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