How to do form validation in angular

by gayathrimohan Updated: Dec 28, 2023

Guide Kit

Angular form validation is a feature in web development. It helps ensure the data entered in a form meets certain criteria or requirements.

It improves the user experience by providing real-time feedback. It prevents submitting invalid or incorrect data. This helps maintain data integrity and accuracy. It leads to better functionality and usability of web applications.

Two main types of form validation:

Client-side validation: It occurs on the user's device using JavaScript. It occurs before sending the form data to the server. It helps provide instant feedback to the user. It highlights any errors or missing information in real-time.
Server-side validation: It takes place on the server after submitting the form data. It involves validating the data against predefined rules or business logic.

Both types of validation are important in web development. Client-side validation boosts the user experience by providing immediate feedback. Server-side validation makes sure of the integrity and security of the processed data.

Angular form validation provides several benefits:

User Experience
Data Integrity
Security
Code Maintainability
Consistent Validation Logic
Form State Management
Custom Validation
Accessibility
Error Messages

In Angular, a form is created using the FormsModule or ReactiveFormsModule. The basic structure involves forming controls and forming groups.

Template-driven Forms (using FormsModule)
Reactive Forms (using ReactiveFormsModule)

Here are some tips for setting up form validation in Angular:

Use Angular Forms Module: Leverage Angular's built-in FormsModule to handle form-related tasks.
Template-Driven Forms: For simpler forms, use template-driven forms with directives. Those are like ngModel for two-way data binding. Add HTML attributes as required for basic validation.
Reactive Forms: For more complex scenarios, prefer reactive forms with FormBuilder. It creates and manages form controls.
Define Validation Rules: Specify validation rules using directives. Those are required, min, max, etc. Create custom validators for unique requirements.
Error Messages: Display meaningful error messages using Angular directives like ngIf and ngFor. Customize error messages based on validation rules.
FormGroup and FormControl: Organize form controls by using both. It manages the form and individual form fields.
Async Validators: Use this for scenarios like checking the used username. Install custom async validators when needed.
Show Validation Feedback: Provide this to users by using CSS classes. It highlights invalid fields. Display error messages near the corresponding form fields.
Dynamic Forms: Handle dynamic forms by adding and removing form controls. Adjust validation rules based on dynamic form changes.
Cross-Field Validation: The validity of one depends on another field.
Form Submission: It disables form submission. It is done until the form is valid to prevent sending incorrect data. Handle form submission with Angular's (ngSubmit) event.
Testing: Write unit tests for your form validation logic to ensure it works as expected. Use tools like Angular Testing Library for effective testing.

Validation rules are crucial for ensuring data accuracy and integrity.

Here are some common types:

Required Fields
Length Validation
Numeric Validation
Date Validation
Email Format
Pattern Matching
Unique Values
Range Validation
Consistency Validation
Custom Validation Rules
Format Validation (Regex)

In conclusion, proper form validation is crucial for a website. It ensures accurate data input and minimizes errors.

Fig: Preview of the output that you will get on running this code from your IDE.

Code

check the angular form is valid in the controller

JavaScriptLines of Code : 48License : Strong Copyleft (CC BY-SA 4.0)

$scope.myforms = {
    Candidateform: {}
};

//HTML will be
<ng-form name="myForms.CandidateForm">...</ng-form>

//TO VALIDATE I DO IT LIKE THIS

$scope.myForms.CandidateForm.$submitted = true // This will run the validators as well, this means form has been submitted.

//OR TO SUBMIT IT PROGRAMATICALLY
$scope.myForms.CandidateForm.$valid

function Controller($scope) {
    $scope.master = {};
    $scope.user = {
         name: "",
         email: ""
    };
    $scope.update = function(user) {
        //$scope.master = angular.copy(user);
        console.log($scope.master)
    };
}
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<html ng-app>
<div ng-app="demo1">
  <div ng-controller="Controller">
    <ng-form novalidate class="simple-form" name="master">
        <legend>User Profile</legend>
        <div class="control-group-error">
            <label class="control-label" for="input-error">Name</label>
            <div class="controls">    
                <input type="text" name="username" ng-model="user.name">
                <span class="help-inline">Please correct the error</span>
            </div>
            <label>E-mail</label>
            <input type="email" name="email" ng-model="user.email">
        </div>
    </ng-form>
    <button class="btn btn-primary" ng-click="update(user)">Save</button>
      <br />
    <pre>{{master.$valid}}</pre>
  </div>
</div>
</html>

Instructions

Follow the steps carefully to get the output easily.

Install Visual Studio Code IDE on your computer.
Create a new HTML file.
Copy the code using the 'Copy' button and create an HTML tag then paste the code inside the tag into that HTML file.
Copy the controller.js code and paste in the JS file created.
Create a script tag inside the body tag Then keep the function lines inside the script tag(refer to preview as well).
Save and run the HTML file directly from the file location to generate the output.

I hope you found this useful.

I found this code snippet by searching for 'How to do form validation in angular ' you can try any such use case!

Environment Tested

I tested this solution in the following versions. Be mindful of changes when working with other versions.

The solution is created and tested in Visual Studio Code 1.85.1.

Using this solution, we are able to do form validation in angular with simple steps. This process also facilities an easy way to use, hassle-free method to create a hands-on working version of code which would help us to do form validation in angular.

FAQ

1. How do you create and confirm forms using Angular Forms?

You can use Template-driven forms to create and confirm forms using Angular Forms. For Reactive Forms, define the form model in the component and associate it with the form in the template. Use validators such as Validators.required to enforce validation rules.

2. Are there any benefits of using Angular Reactive Forms for form validation?

Angular Reactive Forms offers several benefits for form validation. They provide a more explicit and centralized approach to managing form state. Reactive Forms support dynamic form controls and conditional validation. It is easy for unit testing, making it robust for complex scenarios.

3. Can you explain how several built-in validators work in Angular forms?

Angular provides various built-in validators for form validation.

For example,

Validators.required ensures a field is not empty.
Validators.minLength and Validators.maxLength confirm string length.
Validators.pattern allows you to specify a regex pattern for validation.

4. How does AngularJS Form Validation differ from traditional Javascript validation methods?

AngularJS Form Validation is the approach used in AngularJS (1.x). It relies on HTML attributes and CSS classes. It's less structured and explicit compared to Angular. It provides a more powerful and maintainable way to handle form validation.

5. In what ways does the framework of Angular contribute to efficient form validation?

Angular contributes to efficient form validation through its two-way data binding. They are declarative templates, and the Reactive Forms provide a separation of concerns. This allows for a clear structure and easier maintenance. It has the ability to handle complex validation scenarios with ease. The framework's dependency injection system also supports unit testing of form validation logic.

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