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Question

I did forms in Angular 7 and I did *ngIf conditions to say user, that he don't insert all data to forms. A tried to use ! before *ngIf , and it is OK for Visual Studio Code, but it has the opposite effect.

This is error:

[Angular] Identifier 'name' is not defined. '__type' does not contain such a member property messageForm of RegisterComponent

HTML file:

<h1>Log in</h1>

<form [formGroup]="messageForm" (ngSubmit)="onSubmit()">

  <h5 *ngIf="success">Your form is valid!</h5>

  <label>
    Tvoj nick:
    <input type="text" formControlName="name">
    <div *ngIf="submitted && messageForm.controls.name.errors" class="error">
      <div *ngIf="messageForm.controls.name.errors.required">... aale no, tvoj nick potrebujeme, aby si mal svoj tim</div>
    </div>
  </label>

  <label>
    Email:
    <input type="email" formControlName="email">
    <div *ngIf="submitted && messageForm.controls.email.errors" class="error">
      <div *ngIf="messageForm.controls.email.errors.required">Email je dolezity na zasielanie informacii pre teba</div>
    </div>
  </label>

  <label>
    Tvoje heslo:
    <input type="password" formControlName="password">
    <div *ngIf="submitted && messageForm.controls.password.errors" class="error">
      <div *ngIf="messageForm.controls.password.errors.required">Heslo je zaklad registracie!</div>
    </div>
  </label>

  <input type="submit" value="Zaregistruj sa" class="cta">

</form>

TS file:

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

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

  messageForm: FormGroup;
  submitted = false;
  success = false;

  constructor(private formBuilder: FormBuilder) { }

  ngOnInit() {
    this.messageForm = this.formBuilder.group({
      name: ['', Validators.required],
      email: ['', Validators.required],
      password: ['', Validators.required]
    });
  }

  onSubmit(){
    this.submitted = true;

    if(this.messageForm.invalid){
      return;
    }

    this.success = true;
  }
}

Answer 1

Try to set validation this way

<div *ngIf="submitted && f.name.errors" class="invalid-feedback">
          <div *ngIf="f.name.errors.required">Name is required</div>
</div>

In .ts file

get f() { return this.messageForm.controls; }

Update

<div *ngIf="name?.errors.required">Name is required.</div>


this.messageForm = this.formBuilder.group({
  email: ['', [Validators.required, Validators.email]],
  password: ['', [Validators.required, Validators.minLength(3)]]
});

Reference link

Update email validation issue

<div *ngIf="submitted && f.email.errors" class="invalid-feedback">
    <div *ngIf="f.email.errors.required">Email is required</div>
    <div *ngIf="f.email.errors.email">Email must be a valid email address</div>
</div>