AngularJS Tutorial: How to Create a Custom Validation Directive #codingtutorial #angularjs #webdevelopment

In AngularJS, custom validation directives allow you to create your own validation rules for form inputs. This can be very useful when you need to validate specific requirements that are not covered by the built-in validators provided by Angular.

To create a custom validation directive in AngularJS, follow these steps:

Step 1: Set up your AngularJS application
First, make sure you have AngularJS installed in your project. You can include AngularJS in your project by adding a script tag to your HTML file or by using a package manager like npm or yarn.

Step 2: Create a new custom directive
To create a custom validation directive, you need to define a new directive using the directive method provided by AngularJS. Here is an example of a custom directive that validates whether a password contains at least one uppercase letter:

angular.module('myApp').directive('uppercaseValidator', function() {
  return {
    require: 'ngModel',
    link: function(scope, element, attrs, ctrl) {
      ctrl.$validators.uppercase = function(modelValue, viewValue) {
        if (ctrl.$isEmpty(modelValue)) {
          // consider empty models to be valid
          return true;
        }

        // check for at least one uppercase letter
        return /[A-Z]/.test(modelValue);
      };
    }
  };
});

In this example, we define a new directive called uppercaseValidator that requires the ngModel controller. The link function sets up the validation logic, which checks if the input value contains at least one uppercase letter.

Step 3: Add the custom validation directive to your form
To use the custom validation directive in your form, you can add it as an attribute on the input element that you want to validate. Here is an example of how you can use the uppercaseValidator directive in a form:

<form name="myForm">
  <input type="text" name="password" ng-model="vm.password" uppercase-validator>
  <p ng-show="myForm.password.$error.uppercase">Password must contain at least one uppercase letter</p>
</form>

In this example, we add the uppercase-validator attribute to the input element, which triggers the custom validation logic defined in the directive. We also display an error message when the validation fails using the $error object provided by Angular.

And that’s it! You have now created a custom validation directive in AngularJS. You can customize the directive to fit your specific validation requirements by changing the validation logic inside the directive. This allows you to create powerful and flexible validation rules for your forms in AngularJS.