Angular

Angular forms are an integrated part of web applications. They are used to log in, update a profile, enter sensitive information, and perform many other data-entry tasks. Angular provides two different approaches to handling user input through forms: Template-Driven and Reactive.

Template-Driven Approach: This approach is similar to traditional HTML form handling where the form is driven by the template HTML file. Angular automatically creates form models for you. Here are the key points:

• NGModel tag: This is used to bind form controls like input, select, and textarea to the properties of the form model.
• NGControlGroup module: This is used to group multiple controls.
• Form data is exported as JSON values when the submit method is called.
• Basic HTML validations can be used to validate the form fields. For custom validations, directives can be used.

Reactive Approach: This approach is more robust, scalable, reusable, and testable because it uses an explicit, component-based architecture. Here are the key points:

• The component directly manages the data flows between the form controls and the data models.
• Reactive forms are code-driven, meaning you handle form creation in your component code.
• Reactive forms eliminate the anti-pattern of updating the data model via two-way data binding.

The code provided is a simple example of a reactive form in Angular.

import { Component } from ‘@angular/core’;

import { FormGroup, FormControl } from ‘@angular/forms’;

@Component({

  selector: ‘app-profile-editor’,

  templateUrl: ‘./profile-editor.component.html’,

  styleUrls: [‘./profile-editor.component.css’]

})

export class ProfileEditorComponent {

  profileForm = new FormGroup({

    firstName: new FormControl(”),

    lastName: new FormControl(”),

  });

}

Here’s what it does:

• It imports the necessary Angular components.
• It defines a ProfileEditorComponent class with a profileForm property.
• The profileForm property is a FormGroup instance that tracks the value and state of the form control.
• The FormGroup is bound to the form in the template with the formGroup directive, giving you a direct line of communication from the form controls in the template to the FormGroup in the model.
• The form controls firstName and lastName are bound to the form control instances in the FormGroup with the formControlName directive.

In the HTML template, you can bind it like this:

import { Component } from ‘@angular/core’;

import { FormGroup, FormControl } from ‘@angular/forms’;

@Component({

  selector: ‘app-profile-editor’,

  templateUrl: ‘./profile-editor.component.html’,

  styleUrls: [‘./profile-editor.component.css’]

})

export class ProfileEditorComponent {

  profileForm = new FormGroup({

    firstName: new FormControl(”),

    lastName: new FormControl(”),

  });

}

In the HTML template, the form is bound to the profileForm object. The formControlName directive binds the firstName and lastName form controls to the input elements. When the user enters data into these input fields, the form control instances capture the updates in the form model. This allows you to handle user input in a clear and maintainable way.