TypeError: self.context.newUser is undefined on Angular2

Question

When I try to add an input filed on the template I get this errr TypeError: self.context.newUser is undefined

this is the component

import { Component } from '@angular/core';
import { OnInit } from '@angular/core';
import { Router } from '@angular/router';
import { User } from './user';
import { UserService } from './user.service';


@Component({
  selector: 'vista3',
  templateUrl: 'app/vista3.component.html',
  styleUrls:['app/vista3.component.css']
})

export class Vista3Component implements OnInit{
  users: User[] = [];
  newUser: User;

  constructor(
    private router: Router,
    private userService: UserService) {
  }

  ngOnInit(){
    this.userService.getUsers().then( users => this.users = users);
  }
}

the template

<div  class="separar">
  <table class="table table-striped">
      <tr>
        <th>Nombre</th>
        <th>Apellido</th>
      </tr>
        <tr *ngFor="let user of users">
          <td>{{user.name}}</td><td>{{user.lastName}}</td>
        </tr>
  </table>
</div>
<div  class="separar">
  <div class="row">
    <div class="col-xs-12 col-md-3">
      Nombre: <input [(ngModel)]="newUser.name"/>
    </div>
  </div>
</div>

and the user class

export class User{
  name: string;
  lastName: string;
}

I don't know what I'm missing ,angular2 and typescript are new for me, if somebody cann see the problem...

Answer 1

1. It doesn't look like you ever assign anything to newUser class member.

2. The error in trigger in the line [(ngModel)]="newUser.name" .

You try to get name from undefined . I'd recommend using ?. operator.

<input [(ngModel)]="newUser?.name"/>

And also create an empty user in the constructor:

  constructor(
    private router: Router,
    private userService: UserService) {

    this.newUser = new User;
  }

Answer 2

You need to intiliaze newUser first in order to do newUser.name

You can intiliaze like

newUser: User = new User();

and change the User class as by adding a Constructor

export class User{
    constructor(
        public name?: string,
        public lastName?: string
    ) { }
}

Hope this will help