How Do You Build Reactive Forms in Angular 6?

TL;DR

To start using reactive forms in Angular 6, import ReactiveFormsModule, define a FormGroup with FormBuilder, and bind it to HTML fields through formControlName. The tutorial builds five forms, beginning with email, message, and career controls before progressing to nested forms, dynamic fields, validation, and backend submission. Read on for specific setup, binding, value-tracking, and form-organization guidance.

Transcript

today I'm going to show you everything you need to know to start using reactive forms in angular 6 effectively we'll do this by building five different forms that started the absolute basics then progress on to topics like dynamic form fields validation and submitting your form data to a back-end database almost all apps use forms in some capacity ... Read More

Key Insights

• 💁 Angular Material offers UI elements for form validation in Angular 6.
• 💁 Form groups and form builder are essential for building reactive forms in Angular 6.
• 💁 Nested forms and form arrays provide organization and dynamic field addition to forms.
• 😄 Built-in validators in Angular 6 facilitate form validation with ease.
• 💁 Submission of form data to a backend database in Angular 6 can be achieved using Angular Firestore.
• 💁 Managing form states like loading and success are crucial for user feedback in form submissions.
• 💁 Leveraging reactive forms in Angular 6 enables real-time updates and validations in form fields.

Questions & Answers

Q: How do you build a reactive form in Angular 6?

Import ReactiveFormsModule from Angular forms, declare a variable with the FormGroup type, and inject FormBuilder into the component constructor. During ngOnInit, call FormBuilder.group to define the form’s fields, default values, and validation rules.

Q: How do you install Angular Material for Angular 6 form validation?

Run “ng add angular/material” in the Angular 6 project. The tutorial uses Angular Material modules to provide form fields and other UI elements for form validation.

Q: What is the difference between FormGroup and FormBuilder in Angular reactive forms?

FormGroup is the class that ties separate form controls together into one unified form. FormBuilder is a service that makes constructing that form and its data model easier.

Q: How do you connect a reactive FormGroup to HTML?

Bind the formGroup attribute in the HTML form to the form defined in TypeScript. For each field, add formControlName and give it the same attribute name used in the TypeScript data model.

Q: How can you observe reactive form value changes in real time?

Use the FormGroup’s valueChanges method, which returns an observable. Subscribing to it emits the form’s value every time an entered value changes.

Q: How do you set default values in an Angular 6 reactive form?

Provide the default value when defining each field inside FormBuilder.group. An empty string creates an initially empty field, while another value can be supplied when the form should start prefilled.

Q: How do you display a reactive form’s current value in HTML?

Reference the form’s value property in the template and apply the JSON pipe. The displayed value object then reflects changes made to fields such as email, message, and career.

Q: How do nested reactive forms keep Angular 6 forms organized?

Create a reusable FormGroup for related fields, such as the separate parts of a phone number, and place it inside a parent FormGroup. The same nested schema can be reused for multiple entries, including home and cell phone numbers.

Summary & Key Takeaways

• Learn how to set up reactive forms in Angular 6 for dynamic form fields, validation, and backend database submission.

• Utilize Angular Material for UI elements and form validation.

• Explore nested forms, form arrays for dynamic fields, form validation with built-in validators, and submitting form data to a backend database.