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Day 04 Advanced Patterns

Reactive Forms

Angular Reactive Forms give you full programmatic control over form state, validation, and submission. This lesson covers FormBuilder, Validators, custom v

~1 hour Hands-on Precision AI Academy

Today's Objective

Learn the core concepts of Reactive Forms and apply them in practical exercises.

01

Setting Up Reactive Forms

Import ReactiveFormsModule in your module, then build forms in the component class using FormBuilder.

app.module.ts
app.module.ts
imports: [ReactiveFormsModule]
registration.component.ts
registration.component.ts
import { Component } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';

@Component({ selector: 'app-registration', templateUrl: '...' })
export class RegistrationComponent {
  form: FormGroup;

  constructor(private fb: FormBuilder) {
    this.form = this.fb.group({
      name: ['', [Validators.required, Validators.minLength(2)]],
      email: ['', [Validators.required, Validators.email]],
      password: ['', [Validators.required, Validators.minLength(8)]],
      confirmPassword: ['', Validators.required]
    }, { validators: this.passwordMatch });
  }

  // Custom cross-field validator
  passwordMatch(group: FormGroup) {
    const pw = group.get('password')?.value;
    const confirm = group.get('confirmPassword')?.value;
    return pw === confirm ? null : { mismatch: true };
  }

  get nameControl() { return this.form.get('name'); }

  onSubmit() {
    if (this.form.valid) {
      console.log(this.form.value);
    } else {
      this.form.markAllAsTouched();
    }
  }
}
registration.component.html
registration.component.html

  

    
    
    
      Name is required.
      At least 2 characters.
    
  


  

    
    
  


  

    
    
  


  Passwords don't match.
💡
Access control state without the getter boilerplate: form.get('email')?.errors?.['email']. The ?. optional chaining prevents errors when the control hasn't been touched yet.
Next →
Day 5: Build and Deploy
→

Supporting References & Reading

Go deeper with these external resources.

Docs
Reactive Forms Official documentation for angular.
→
GitHub
Reactive Forms Open source examples and projects for Reactive Forms
→
MDN
MDN Web Docs Comprehensive web technology reference
→

Day 4 Checkpoint

Before moving on, confirm understanding of these key concepts:

Continue To Day 5
Day 5 of the Angular in 5 Days course
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