$setValidity() function not updating form status

The $setValidity() function in AngularJS is used to programmatically change the validity of a form control or a field in a form. It allows you to manually set the validity of a field to true or false for specific validation rules, but if it’s not working as expected, there may be a few issues to investigate. Below is a step-by-step guide on what might be going wrong and how to fix it.

1. Understanding $setValidity()

Before we dive into the troubleshooting process, let’s understand how $setValidity() works. This function allows you to specify a validation rule and set the field’s validity accordingly. The syntax for $setValidity() is:

formControl.$setValidity(validationName, isValid);

• validationName: The name of the validation rule you want to apply. This can be a custom validation name or one of the built-in validation rules (e.g., required, pattern, minlength).
• isValid: A boolean (true or false) representing the validity of the control.

For example, in a custom directive, you can use $setValidity() to programmatically mark a field as invalid or valid:

$scope.myForm.myField.$setValidity('customError', false);

This would mark the myField as invalid with a custom validation error named 'customError'.

2. Common Causes of $setValidity() Not Working

If $setValidity() is not updating the form status as expected, there are several common causes:

2.1 Calling $setValidity() Too Late

In some cases, $setValidity() may not work because it’s being called too late in the digest cycle. AngularJS runs validation checks during the digest cycle, so if you modify the validity of a form control after the digest cycle has already run, the form control might not be updated.

Fix:

Make sure that you’re calling $setValidity() inside an AngularJS context, such as within a $scope method or inside a $timeout or $apply if you’re updating the validity outside of AngularJS’s scope.

$scope.$apply(function() {
    $scope.myForm.myField.$setValidity('customError', false);
});

This ensures that the validity change happens within AngularJS’s digest cycle.

2.2 Incorrect Form Control Reference

Make sure you’re referencing the correct form control. For instance, if you’re trying to change the validity of a control, ensure you’re using the correct scope reference to the form control.

Example:

<form name="myForm">
    <input type="text" name="username" ng-model="username" ng-minlength="5">
</form>

In the controller, you need to reference the correct form control like this:

$scope.myForm.username.$setValidity('minlength', false);

If you reference the form control incorrectly (e.g., by using $scope.username instead of $scope.myForm.username), it won’t work.

2.3 Not Updating the Correct Field’s Validity

If you’re trying to update the validity of a specific field, ensure you’re modifying the correct form control. If your form contains multiple controls, confirm that you’re applying $setValidity() to the specific control’s $valid state.

For example:

$scope.myForm.username.$setValidity('usernameError', false);

If the name of the control is wrong (e.g., myForm.username instead of myForm.email), the validity won’t be updated for the expected field.

2.4 Issue with $validators

If you’re using custom $validators (e.g., a custom validation rule), make sure you’re not interfering with the built-in validation or other custom rules when calling $setValidity().

Example:

app.directive('customValidator', function() {
    return {
        require: 'ngModel',
        link: function(scope, element, attrs, ngModel) {
            ngModel.$validators.custom = function(modelValue, viewValue) {
                if (modelValue) {
                    return modelValue.length > 5;  // Custom validation logic
                }
                return true;
            };
        }
    };
});

In this case, the $setValidity() function won’t trigger unless the custom validator is involved in the process. So, ensure that the validator is working as expected.

2.5 Using $setValidity() on Form Controls Before They Are Initialized

If you’re trying to call $setValidity() on form controls before they are initialized, AngularJS might not be able to track the validity of the control correctly.

For example, trying to call $setValidity() on a control that hasn’t been rendered or initialized yet will result in AngularJS ignoring the change.

Fix:

Make sure you’re interacting with the form and controls after the form has been fully initialized. You can use ng-init or lifecycle hooks such as ngAfterViewInit (if using Angular 2+).

3. Example Implementation of $setValidity()

Let’s walk through a practical example to ensure that $setValidity() works correctly.

HTML:

<form name="myForm">
    <input type="text" name="username" ng-model="username" ng-minlength="5" required>
    <span ng-show="myForm.username.$error.minlength">Username must be at least 5 characters long.</span>
    <button type="submit" ng-disabled="myForm.$invalid">Submit</button>
</form>

Controller:

app.controller('FormController', function($scope) {
    $scope.username = '';
    // Set the custom error for the username field if it's invalid
    $scope.$watch('username', function(newVal) {
        if (newVal && newVal.length < 5) {
            $scope.myForm.username.$setValidity('minlength', false);
        } else {
            $scope.myForm.username.$setValidity('minlength', true);
        }
    });
});

In this example, we manually update the validity of the username field. Whenever the value of username is less than 5 characters, we mark it as invalid. This can be controlled dynamically using $watch.

4. Debugging $setValidity()

If $setValidity() is still not updating the form status, here are some debugging steps:

1. Inspect the form and control: Use console.log($scope.myForm) and inspect the status of your form controls.
2. Check $invalid property: Ensure that the $invalid property is being updated as expected when you call $setValidity(). For example: console.log($scope.myForm.$invalid); // This should be true if the form is invalid
3. Verify the control’s validity status: Check if the control has $valid, $invalid, $error, or $pristine properties. If any of these are incorrect, $setValidity() might not be functioning properly.