prepopulating reactive form shoud check form control validation code example

Example 1: form builder validation messages on touched

import { Component, OnInit } from '@angular/core';
import { Validators, FormGroup, FormBuilder } from '@angular/forms';
import { CustomvalidationService } from '../services/customvalidation.service';

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

  registerForm: FormGroup;
  submitted = false;

  constructor(
    private fb: FormBuilder,
    private customValidator: CustomvalidationService
  ) { }

  ngOnInit() {
    this.registerForm = this.fb.group({
      name: ['', Validators.required],
      email: ['', [Validators.required, Validators.email]],
      username: ['', [Validators.required], this.customValidator.userNameValidator.bind(this.customValidator)],
      password: ['', Validators.compose([Validators.required, this.customValidator.patternValidator()])],
      confirmPassword: ['', [Validators.required]],
    },
      {
        validator: this.customValidator.MatchPassword('password', 'confirmPassword'),
      }
    );
  }

  get registerFormControl() {
    return this.registerForm.controls;
  }

  onSubmit() {
    this.submitted = true;
    if (this.registerForm.valid) {
      alert('Form Submitted succesfully!!!\n Check the values in browser console.');
      console.table(this.registerForm.value);
    }
  }
}

Example 2: form builder validation messages on touched

<div class="container">
    <div class="row">
        <div class="col-md-8 mx-auto">
            <div class="card">
                <div class="card-header">
                    <h3>Angular Reactive Form</h3>
                </div>
                <div class="card-body">
                    <form class="form" [formGroup]="registerForm" (ngSubmit)="onSubmit()">
                        <div class="form-group">
                            <label>Name</label>
                            <input type="text" class="form-control" formControlName="name">
                            <span class="text-danger"
                                *ngIf="(registerFormControl.name.touched || submitted) && registerFormControl.name.errors?.required">
                                Name is required
                            </span>
                        </div>
                        <div class="form-group">
                            <label>Email</label>
                            <input type="text" class="form-control" formControlName="email">
                            <span class="text-danger"
                                *ngIf="(registerFormControl.email.touched || submitted) && registerFormControl.email.errors?.required">
                                Email is required
                            </span>
                            <span class="text-danger"
                                *ngIf="registerFormControl.email.touched && registerFormControl.email.errors?.email">
                                Enter a valid email address
                            </span>
                        </div>
                        <div class="form-group">
                            <label>User Name</label>
                            <input type="text" class="form-control" formControlName="username">
                            <span class="text-danger"
                                *ngIf="(registerFormControl.username.touched || submitted) && registerFormControl.username.errors?.required">
                                User Name is required
                            </span>
                            <span class="text-danger"
                                *ngIf="registerFormControl.username.touched && registerFormControl.username.errors?.userNameNotAvailable">
                                User Name is not available
                            </span>
                        </div>
                        <div class="form-group">
                            <label>Password</label>
                            <input type="password" class="form-control" formControlName="password">
                            <span class="text-danger"
                                *ngIf="(registerFormControl.password.touched || submitted) && registerFormControl.password.errors?.required">
                                Password is required
                            </span>
                            <span class="text-danger"
                                *ngIf="registerFormControl.password.touched && registerFormControl.password.errors?.invalidPassword">
                                Password should have minimum 8 characters, at least 1 uppercase letter, 1 lowercase
                                letter and 1 number
                            </span>
                        </div>
                        <div class="form-group">
                            <label>Confirm Password</label>
                            <input type="password" class="form-control" formControlName="confirmPassword">
                            <span class="text-danger"
                                *ngIf="(registerFormControl.confirmPassword.touched || submitted)&& registerFormControl.confirmPassword.errors?.required">
                                Confirm Password is required
                            </span>
                            <span class="text-danger"
                                *ngIf="registerFormControl.confirmPassword.touched && registerFormControl.confirmPassword.errors?.passwordMismatch">
                                Passwords doesnot match
                            </span>
                        </div>
                        <div class="form-group">
                            <button type="submit" class="btn btn-success">Register</button>
                        </div>
                    </form>
                </div>
            </div>
        </div>
    </div>
</div>