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Angular 6 Forms Tutorial Example From Scratch

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Angular 6 Forms Tutorial Example From Scratch. Angular offers two form-building technologies: reactive forms and template-driven forms. The two technologies belong to the @angular/forms library and share a standard set of form control classes. In this example, we will see Reactive Forms.

Reactive forms

Angular reactive forms facilitate a reactive style of programming that favors explicit management of the data flowing between a non-UI data model (typically retrieved from a server) and a UI-oriented form model that retains the states and values of the HTML controls on the screen. Reactive forms offer the ease of using reactive patterns, testing, and validation.

With reactive forms, you create a tree of Angular form control objects in the component class and bind them to native form control elements in the component template.

Template-driven forms

In template-driver forms, you place HTML form controls (such as <input> and <select>) in the component template and bind them to data model properties in the component, using directives like ngModel. You don’t create Angular form control objects.

Angular directives create them for you, using the information in your data bindings. You don’t push and pull data values. Angular handles that for you with ngModel.

Angular 6 Forms Tutorial Example

Firstly, we install our Angular 6 project using Angular CLI.

#1: Install Angular 6

If you have not installed Angular CLI globally on your machine, then install it using the following command.

npm install -g @angular/cli

# or

yarn add global @angular/cli

Now, create a local project using the following command.

ng new forms

Now, start the application using the following command.

ng serve --open

#2: Include Bootstrap 4 in Angular 6.

Go to your terminal and install Bootstrap 4 using the following code.

npm install bootstrap 4 --save

After that go to the inside src folder and open styles.css file and import the bootstrap.min.css file.

@import "~bootstrap/dist/css/bootstrap.min.css";

Save the file, and if your development server is running then, you can see the changes at http://localhost:4200/

#3: Import ReactiveFormsModule.

Inside src >> app >> app.module.ts file, import the ReactiveFormsModule.

// app.module.ts

import { ReactiveFormsModule } from '@angular/forms';

imports: [
  BrowserModule,
  ReactiveFormsModule
],

#4: Import FormGroup and FormControl.

Now, we will create a form inside app.component.ts.

So, we need to import FormControl and FormGroup class inside an app.component.ts file.

// app.component.ts

import { Component } from '@angular/core';
import { FormControl, FormGroup } from '@angular/forms';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'app';
  angularForm = new FormGroup ({
    name: new FormControl()
  });
}

So, what I have done are import FormControl and FormGroup modules.

Next, Create a form object called angularForm and pass the input called name.

All the form controls are also a form object.

So, angularForm is root html form object.

Inside all the input types are sub-objects.

Now, we can create a form inside an app.component.html file.

#5: Create a form.

Write the following code inside an app.component.html file.

<h2>Angular 6 Forms</h2>
<form [formGroup]="angularForm">
  <div class="form-group">
    <label class="center-block">Name:
      <input class="form-control" formControlName="name">
    </label>
  </div>
</form>

So, we have assigned the formGroup called angularForm. We have created formGroup inside app.component.ts file already, we have just assigned them to the form element.

Also, we have created a formControl attribute called name inside an app.component.ts file, here we have assigned it to the form input type.

Save the file and go to the: http://localhost:4200/

You can see the form.

Angular 6 Forms Tutorial Example

 

#6: Import FormBuilder module.

The FormBuilder class helps reduce repetition and clutter by handling details of control creation for you.

Import FormBuilder class inside app.module.ts file.

// app.component.ts

import { Component } from '@angular/core';
import { FormControl, FormGroup, FormBuilder } from '@angular/forms';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'app';
  angularForm = new FormGroup ({
    name: new FormControl()
  });
  constructor(private fb: FormBuilder) { // <--- inject FormBuilder
    this.createForm();
  }
  createForm() {
    this.angularForm = this.fb.group({
      name: '',
    });
  }
}

FormBuilder.group is a factory method that creates a FormGroup.   FormBuilder.group takes an object whose keys and values are FormControl names and their definitions. In this example, the name control is defined by its initial data value, an empty string.

#7: Insert Validation into the field.

First, we need to import Validators module inside an app.component.ts file.

// app.component.ts

import { FormControl, FormGroup, FormBuilder, Validators } from '@angular/forms';

Now, we just need to pass an array as a value to the name property.

// app.component.ts

createForm() {
    this.angularForm = this.fb.group({
      name: ['', Validators.required ],
    });
}

#8: Display Angular 6 Validation Errors.

Now, I have changed the form design and added the validation errors.

If the error occurs then it displays in the form. If any error is still there, then the submit button is disabled.

<!-- app.component.html -->

<div class="container">
    <h1>
      Angular 6 Forms
    </h1>
    <form [formGroup]="angularForm" novalidate>
          <div class="form-group">
              <label>Name:</label>
              <input class="form-control" formControlName="name" type="text">
          </div>
          <div *ngIf="angularForm.controls['name'].invalid && (angularForm.controls['name'].dirty || angularForm.controls['name'].touched)" class="alert alert-danger">
              <div *ngIf="angularForm.controls['name'].errors.required">
                Name is required.
              </div>
          </div>
          <button type="submit"
              [disabled]="angularForm.pristine || angularForm.invalid" class="btn btn-success">
              Save
          </button>
    </form>
    <br />
  </div>

 

Angular 6 Forms Validation Tutorial With Example

Finally, we have completed Angular 6 Forms Tutorial Example From Scratch.

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