AngularJS can validate input data.
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.
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Client-side validation cannot alone secure user input. Server side validation is also necessary. |
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Use
the HTML5 attribute required to specify that the input field must
be filled out:
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.$valid}}</h1>
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Use the HTML5 type email to specify that the value must be an e-mail:
input field has to be an e-mail:
<form name="myForm">
<input name="myInput" ng-model="myInput"
type="email">
</form>
<p>The input's valid state is:</p>
<h1>{{myForm.myInput.$valid}}</h1>
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AngularJS is constantly updating the state of both the form and the input fields.
Input fields have the following states:
$untouched The field has not been touched yet$touched The field has been touched$pristine The field has not been modified yet$dirty The field has been modified$invalid The field content is not valid$valid The field content is validThey are all properties of the input field, and are either true
or false.
Forms have the following states:
$pristine No fields have been modified yet$dirty One or more have been modified$invalid The form content is not valid$valid The form content is valid$submitted The form is submittedThey are all properties of the form, and are either true
or false.
You can use these states to show meaningful messages to the user. Example, if a field is required, and the user leaves it blank, you should give the user a warning:
Show an error message if the field has been touched AND is empty:
<input name="myName" ng-model="myName" required>
<span ng-show="myForm.myName.$touched
&& myForm.myName.$invalid">The name is required.</span>
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AngularJS adds CSS classes to forms and input fields depending on their states.
following classes are added to, or removed from, input fields:
ng-untouched The field has not been touched yetng-touched The field has been touchedng-pristine The field has not been modified yetng-dirty The field has been modifiedng-valid The field content is validng-invalid The field content is not validng-valid-key One key for each validation.
Example: ng-valid-required, useful when there are more than one
thing that must be validatedng-invalid-key Example: ng-invalid-requiredfollowing classes are added to, or removed from, forms:
ng-pristine No fields has not been modified yetng-dirty One or more fields has been modifiedng-valid The form content is validng-invalid The form content is not validng-valid-key One key for each validation.
Example: ng-valid-required, useful when there are more than one
thing that must be validatedng-invalid-key Example: ng-invalid-requiredclasses 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.
Apply styles, using standard CSS:
<style>
input.ng-invalid {
background-color: pink;
}
input.ng-valid {
background-color: lightgreen;
}
</style>
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Forms can also be styled:
Apply styles for unmodified (pristine) forms, and for modified forms:
<style>
form.ng-pristine {
background-color: lightblue;
}
form.ng-dirty {
background-color: pink;
}
</style>
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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.
Create your own directive, containing a custom validation function, and refer
to it by using my-directive.
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>
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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.$parsers.push(myValidation); will add the
myValidation function to an array of other functions, which will be
executed every time the input value changes.
<!DOCTYPE html>
<html>
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.8/angular.min.js"></script>
<body>
<h2>Validation Example</h2>
<form ng-app="myApp"
ng-controller="validateCtrl"
name="myForm" novalidate>
<p>Username:<br>
<input type="text" name="user" ng-model="user"
required>
<span style="color:red" ng-show="myForm.user.$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 = 'john.doe@gmail.com';
});
</script>
</body>
</html>
Try it Yourself »
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HTML form attribute novalidate is used to disable default browser validation. |
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AngularJS directive ng-model binds the input elements to the model.
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.