Article by: Manish Methani
Last Updated: September 14, 2021 at 2:04pm IST
Table of Contents:
Forms are an essential part of web applications, allowing users to interact with your website. In Angular, you can create user-friendly input forms with ease. In this post, we'll guide you through the process of building input forms and implementing validation using Angular, using an example project.
Angular offers two approaches for creating forms: Template-Driven Forms and Reactive Forms. Let's understand each approach with an example project.
For our example project, we'll build a simple user registration form with fields for username, email, and password.
Template-Driven Forms are ideal for simple forms. In your project:
app.module.ts
file, import FormsModule
from @angular/forms
.import { FormsModule } from "@angular/forms"; @NgModule({ imports: [FormsModule], // ... })
user-registration.component.html
), create the form using Angular directives:<form #userForm="ngForm"> <div class="form-group"> <label for="username">Username</label> <input type="text" id="username" name="username" [(ngModel)]="user.username" required> </div> <div class="form-group"> <label for="email">Email</label> <input type="email" id="email" name="email" [(ngModel)]="user.email" required email> </div> <div class="form-group"> <label for="password">Password</label> <input type="password" id="password" name="password" [(ngModel)]="user.password" required minlength="8"> </div> <button type="submit" [disabled]="userForm.invalid">Register</button> </form>
#userForm
) and ngModel
.Reactive Forms provide more control and are suitable for complex forms. In our project:
app.module.ts
file, import ReactiveFormsModule
from @angular/forms
.import { ReactiveFormsModule } from "@angular/forms"; @NgModule({ imports: [ReactiveFormsModule], // ... })
user-registration.component.ts
), define the form controls, form group, and form builder:import { FormBuilder, FormGroup, Validators } from "@angular/forms"; export class UserRegistrationComponent { userForm: FormGroup; constructor(private fb: FormBuilder) { this.userForm = this.fb.group({ username: ["", [Validators.required]], email: ["", [Validators.required, Validators.email]], password: ["", [Validators.required, Validators.minLength(8)]], }); } }
user-registration.component.html
), bind the form controls:<form [formGroup]="userForm" (ngSubmit)="onSubmit()"> <div class="form-group"> <label for="username">Username</label> <input type="text" id="username" formControlName="username"> </div> <div class="form-group"> <label for="email">Email</label> <input type="email" id="email" formControlName="email"> </div> <div class="form-group"> <label for="password">Password</label> <input type="password" id="password" formControlName="password"> </div> <button type="submit" [disabled]="userForm.invalid">Register</button> </form>
Form validation is crucial for ensuring data integrity. Angular provides built-in validators and the ability to create custom validators.
Let's add validation to our user registration form.
Built-in Validators
Angular offers various built-in validators like required
, minLength
, maxLength
, and pattern
. For example, we added required
, email
, and minlength
validators to the email and password fields.
You can create custom validators for specific validation needs. For instance, you can create a custom validator to check if a username is available:
function usernameAvailabilityValidator(control: AbstractControl): { [key: string]: boolean } | null { const username = control.value; // Check availability logic here if (/* username is not available */) { return { "usernameTaken": true }; } return null; } // Add the validator to your form control this.userForm = this.fb.group({ username: ["", [Validators.required], [usernameAvailabilityValidator]], });
Displaying validation errors to users in a user-friendly way is crucial. We can use Angular's ngIf
and ngClass
directives for this purpose:
<div *ngIf="userForm.get("username").invalid && userForm.get("username").touched"> <div *ngIf="userForm.get("username").hasError("required")">Username is required.</div> </div>
Creating user-friendly input forms with Angular is a breeze, thanks to its powerful form handling and validation capabilities. Whether you choose Template-Driven Forms or Reactive Forms depends on your project's requirements, but both offer robust solutions for building forms.
In our example project, we built a user registration form with validation. You can expand upon this project to include more features and customize it to fit your application's needs.
Remember to follow best practices for form validation, and your users will appreciate the user-friendly experience you provide.
Happy coding!
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Angular Forms are a crucial part of web applications that enable user interaction by allowing users to input data and submit it to the server. They are used for tasks like user registration, login, and data submission.
In Angular, you can create forms using two approaches: Template-Driven Forms and Reactive Forms. Template-Driven Forms rely on directives in the template, while Reactive Forms use a programmatic approach to define forms using TypeScript.
Template-Driven Forms are suitable for simpler forms with basic validation requirements. They are easier to set up and ideal for forms that don"t require complex logic or dynamic form controls.
Reactive Forms are more suitable for complex forms with dynamic form controls, advanced validation, and scenarios where you need more programmatic control over your forms. They offer greater flexibility and scalability.
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