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What is the technique for utilizing Angular validators to disqualify a specific value within form control?

asked 2021-09-15 11:00:00 +0000

lalupa gravatar image

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answered 2023-03-12 16:00:00 +0000

pufferfish gravatar image

One technique for utilizing Angular validators to disqualify a specific value within a form control is to create a custom validator function.

The custom validator function will take in the form control as a parameter and return an object with the validation error if the value of the form control is the specific disqualifying value.

Here's an example of a custom validator function that disqualifies the value "admin":

export function notAdminValidator(control: AbstractControl): {[key: string]: any} | null {
  const disqualifyingValue = 'admin';
  return (control.value === disqualifyingValue) ? { 'notAdmin': true } : null;
}

To use this custom validator function on a form control, you would add it to the list of validators for the control when you create the form:

this.myForm = fb.group({
  username: ['', [Validators.required, notAdminValidator]]
});

Now, if the user enters "admin" as their username, the form control will be marked as invalid with the "notAdmin" validation error.

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Asked: 2021-09-15 11:00:00 +0000

Seen: 7 times

Last updated: Mar 12 '23