Angular is a popular front-end web development framework that provides developers with a range of tools and features to build dynamic and interactive web applications.
One of these features is reactive forms, which allow developers to create forms that react to user input in real-time.
In this blog post, we will discuss how to use reactive forms in Angular, including creating a form, adding form controls, and validating user input.
Creating a Reactive Form
To create a reactive form in Angular, you first need to import the necessary modules. In the app.module.ts file, import the ReactiveFormsModule from the @angular/forms package. Then, add it to the imports array.
import { ReactiveFormsModule } from '@angular/forms';
@NgModule({
imports: [
BrowserModule,
ReactiveFormsModule
],
declarations: [AppComponent],
bootstrap: [AppComponent]
})
export class AppModule { }Next, create a new FormGroup instance in your component file. A FormGroup is a collection of form controls, and it is the top-level object for reactive forms.
import { Component } from '@angular/core';
import { FormGroup, FormControl } from '@angular/forms';
@Component({
selector: 'app-form',
template: `
<form [formGroup]="form">
<input formControlName="name" placeholder="Name">
</form>
`,
})
export class FormComponent {
form = new FormGroup({
name: new FormControl(''),
});
}
In this example, we create a form with a single form control called “name”. The FormControl constructor takes an initial value as its argument.
Adding Form Controls
To add more form controls, simply add them to the FormGroup object. For example, to add an email field:
form = new FormGroup({
name: new FormControl(''),
email: new FormControl('')
});
In the template, add a new input field for the email control:
<form [formGroup]="form"> <input formControlName="name" placeholder="Name"> <input formControlName="email" placeholder="Email"> </form>
Validating User Input
Reactive forms in Angular also provide built-in validation features. To add validation to a form control, you can add validators to the FormControl constructor. For example, to require a name field, add the Validators.required function:
form = new FormGroup({
name: new FormControl('', Validators.required),
email: new FormControl('')
});
In the template, you can display error messages for invalid fields using the *ngIf directive:
<form [formGroup]="form">
<input formControlName="name" placeholder="Name">
<div *ngIf="form.get('name').invalid && (form.get('name').dirty || form.get('name').touched)" class="error-message">
Name is required.
</div>
<input formControlName="email" placeholder="Email">
</form>
This will display an error message when the name field is invalid and has been either touched or modified.
Conclusion
Reactive forms are a powerful feature in Angular that enable developers to create dynamic and interactive forms that respond to user input in real-time.
In this blog post, we covered the basics of how to create a reactive form, add form controls, and validate user input.
By mastering reactive forms, you can build more engaging and user-friendly web applications.
Moreover, this blog post is fabricated by the content experts at Accrete Infosolution Technologies LLP, a reliable web development service provider that has years of expertise in providing IT services across the globe. Contact us today to hire web developers for your dream project!
You Might Also Like:
How To Make A Python Calculator ?
How to Load and Use Custom Fonts with CSS ?
How to Add Multiple Records in SQL ?