What are the best practices for utilizing Angular form validation effectively?

I am currently working on implementing form validation in my project. I have created a basic login form and now I want to validate the input fields before submitting them to the server, while also providing visual feedback to the user if the inputs are invalid. I attempted to follow the guidelines outlined in the official documentation, but encountered some challenges.

Here is the code snippet that I have developed so far:

<div class="content">
    <section>
        <div class="form-wrapper">
            <h3>Register</h3>
            <form class="form" [formGroup]="form" (submit)="submit()">
                <div class="form-item">
                    <input type="text" formControlName="name" placeholder="Name" required>
                </div>
                <div class="form-item">
                    <input formControlName="email" type="email" placeholder="Email Address" required>
                </div>
                <div class="form-item">
                    <input formControlName="password" type="password" placeholder="Password" required>
                </div>
                <div class="form-item">
                    <button type="submit">Register</button>
                </div>
            </form>
        </div>
    </section>
</div>

Additionally, here is the corresponding component.ts file:

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, FormControl } from '@angular/forms';
import { AuthService } from 'src/app/services/auth.service';
import { Router } from '@angular/router';
import { Validators } from '@angular/forms';

@Component({
  selector: 'app-register',
  templateUrl: './register.component.html',
  styleUrls: ['./register.component.scss']
})
export class RegisterComponent implements OnInit {

  form: FormGroup;
  name: string = '';
  email: string = '';
  password: string = '';
  error: string = '';

  constructor( private auth: AuthService, private router: Router) { }

  ngOnInit(): void {
    this.form = new FormGroup({
      name: new FormControl(this.name,[
        Validators.required,
      ]),
      email: new FormControl(this.email,[
        Validators.required,
        Validators.pattern("^[a-z0-9._%+-]+@[a-z0-9.-]+\\.[a-z]{2,4}$")
      ]),
      password: new FormControl(this.password, [
        Validators.required,
        Validators.minLength(8)
      ])
    })
  }

  submit(){
    this.auth.tryRegister(this.form.getRawValue())
    .subscribe(
      res => {
        if(res.status == 200){
          this.router.navigate(['/verify'])
        }},
      err => {
        if(err.status == 400){
          this.error = 'Invalid form data'
        }
        else if(err.status == 401){
          this.error = 'email address already in use'
        }
      })
  }
}

In order to visually indicate an invalid email address, I would like to apply the styling of my custom class ".is-invalid", which adds a red border around the input tag. If there are any existing Angular CSS classes for achieving this effect, I would be open to utilizing them as well.

As I am relatively new to Angular development, any guidance or recommended resources for accomplishing this task properly would be greatly appreciated.

Edit: I have implemented getters for my properties, but I am still encountering issues. Whenever I attempt to check

*ngIf="name.errors?.required"
, I receive the error "object is possibly null", despite using the safe navigation operator ?.

Answer №1

One way to access form controls in the HTML view is by creating a getter for them in the corresponding .ts file:

get username() {
    return this.form.get('username');
}

After that, you can use it in the HTML view like this:

<div class="error" *ngIf="username.errors?.required">
    Username is required.
</div>

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