AngularJS Form Validation
AngularJS can validate input data.
Form Validation
AngularJS offers client-side form validation.
AngularJS monitors the state of the form and input fields (input, textarea, select), and lets you notify the user about the current state.
AngularJS also holds information about whether they have been touched, or modified, or not.
You can use standard HTML5 attributes to validate input, or you can make your own validation functions.
Client-side validation cannot alone secure user input. Server side validation is also necessary.
Required
Use
the HTML5 attribute required to specify that the input field must
be filled out:
Example
The input field is required:
<form name="myForm">
<input name="myInput" ng-model="myInput"
required>
</form>
<p>The input's valid state is:</p>
<h1>{{myForm.myInput.$valid}}</h1>
Try it Yourself »
Use the HTML5 type email to specify that the value must be an e-mail:
Example
The input field has to be an e-mail:
<form name="myForm">
<input name="myInput" ng-model="myInput"
type="email">
</form>
<p>The input's valid state is:</p>
<h1>{{myForm.myInput.$valid}}</h1>
Try it Yourself »
Form State and Input State
AngularJS is constantly updating the state of both the form and the input fields.
Input fields have the following states:
$untouchedThe field has not been touched yet$touchedThe field has been touched$pristineThe field has not been modified yet$dirtyThe field has been modified$invalidThe field content is not valid$validThe field content is valid
They are all properties of the input field, and are either true
or false.
Forms have the following states:
$pristineNo fields have been modified yet$dirtyOne or more have been modified$invalidThe form content is not valid$validThe form content is valid$submittedThe form is submitted
They are all properties of the form, and are either true
or false.
You can use these states to show meaningful messages to the user. Example, if a field is required, and the user leaves it blank, you should give the user a warning:
Example
Show an error message if the field has been touched AND is empty:
<input name="myName" ng-model="myName" required>
<span ng-show="myForm.myName.$touched
&& myForm.myName.$invalid">The name is required.</span>
Try it Yourself »
CSS Classes
AngularJS adds CSS classes to forms and input fields depending on their states.
The following classes are added to, or removed from, input fields:
ng-untouchedThe field has not been touched yetng-touchedThe field has been touchedng-pristineThe field has not been modified yetng-dirtyThe field has been modifiedng-validThe field content is validng-invalidThe field content is not validng-valid-keyOne key for each validation. Example:ng-valid-required, useful when there are more than one thing that must be validatedng-invalid-keyExample:ng-invalid-required
The following classes are added to, or removed from, forms:
ng-pristineNo fields has not been modified yetng-dirtyOne or more fields has been modifiedng-validThe form content is validng-invalidThe form content is not validng-valid-keyOne key for each validation. Example:ng-valid-required, useful when there are more than one thing that must be validatedng-invalid-keyExample:ng-invalid-required
The classes are removed if the value they represent is false.
Add styles for these classes to give your application a better and more intuitive user interface.
Example
Apply styles, using standard CSS:
<style>
input.ng-invalid {
background-color: pink;
}
input.ng-valid {
background-color: lightgreen;
}
</style>
Try it Yourself »
Forms can also be styled:
Example
Apply styles for unmodified (pristine) forms, and for modified forms:
<style>
form.ng-pristine {
background-color: lightblue;
}
form.ng-dirty {
background-color: pink;
}
</style>
Try it Yourself »
Custom Validation
To create your own validation function is a bit more tricky; You have to add a new directive to your application, and deal with the validation inside a function with certain specified arguments.
Example
Create your own directive, containing a custom validation function, and refer
to it by using my-directive.
The field will only be valid if the value contains the character "e":
<form name="myForm">
<input name="myInput" ng-model="myInput" required
my-directive>
</form>
<script>
var app = angular.module('myApp',
[]);
app.directive('myDirective', function() {
return {
require: 'ngModel',
link: function(scope, element,
attr, mCtrl) {
function myValidation(value)
{
if (value.indexOf("e") > -1)
{
mCtrl.$setValidity('charE',
true);
} else {
mCtrl.$setValidity('charE', false);
}
return value;
}
mCtrl.$parsers.push(myValidation);
}
};
});
</script>
Try it Yourself »
Example Explained:
In HTML, the new directive will be referred to by using the attribute
my-directive.
In the JavaScript we start by adding a new directive named myDirective.
Remember, when naming a directive, you must use a camel case name,
myDirective, but when invoking it, you must use - separated name,
my-directive.
Then, return an object where you specify that we require ngModel,
which is the ngModelController.
Make a linking function which takes some arguments, where the fourth
argument, mCtrl, is the ngModelController,
Then specify a function, in this case named myValidation, which
takes one argument, this argument is the value of the input element.
Test if the value contains the letter "e", and set the validity of the model
controller to either true or false.
At last, mCtrl.$parsers.push(myValidation); will add the
myValidation function to an array of other functions, which will be
executed every time the input value changes.
Validation Example
<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script>
<body>
<h2>Validation Example</h2>
<form ng-app="myApp"
ng-controller="validateCtrl"
name="myForm" novalidate>
<p>Username:<br>
<input type="text" name="user" ng-model="user"
required>
<span style="color:red" ng-show="myForm.user.$dirty &&
myForm.user.$invalid">
<span ng-show="myForm.user.$error.required">Username
is required.</span>
</span>
</p>
<p>Email:<br>
<input type="email" name="email" ng-model="email" required>
<span
style="color:red" ng-show="myForm.email.$dirty && myForm.email.$invalid">
<span ng-show="myForm.email.$error.required">Email is required.</span>
<span ng-show="myForm.email.$error.email">Invalid email address.</span>
</span>
</p>
<p>
<input type="submit"
ng-disabled="myForm.user.$dirty && myForm.user.$invalid ||
myForm.email.$dirty && myForm.email.$invalid">
</p>
</form>
<script>
var app = angular.module('myApp', []);
app.controller('validateCtrl',
function($scope) {
$scope.user = 'John Doe';
$scope.email = '[email protected]';
});
</script>
</body>
</html>
Try it Yourself »
The HTML form attribute novalidate is used to disable default browser validation.
Example Explained
The AngularJS directive ng-model binds the input elements to the model.
The model object has two properties: user and email.
Because of ng-show, the spans with color:red are displayed only when user or email is $dirty and $invalid.
