title: How to bind the attribute value with a variable in angular 8?
body: <p>I'm developing a virtual store and i need to make a comment with a logged user and save his id in my database.
  so i need to pass the id of the logged user in the value attribute of my hidden input and update the model too. 
  But when i click on the save icon ,i don't get the id in my model 
  Can you help me with this? </p>
  
  <p>This is my model in my ts file of the component</p>
  
  <pre><code>    comentario: '',
      producto_id: '',
      usuario_id: '',
      estado: '',
      created_at: new Date(),
      update_at: new Date(),
    } ``` 
  
  
  This is one of my input 
  ``` &lt;input type="hidden" name="usuario_id" (ngModelChange)="comentario.usuario_id" value="{{user.id}}" class="form-control" ng-init="comentario.usuario_id=user.id"&gt;``` 
  
  I expect to see the element of the variable {{user.id}} in my model but the current is the default one of my model 
  
  comentario: "ddsdsd"
  ​
  created_at: Date 2019-06-28T11:39:40.014Z
  ​
  estado: ""
  ​
  producto_id: ""
  ​
  update_at: Date 2019-06-28T11:39:40.014Z
  ​
  usuario_id: "1" I expect to get this from my {{user.id}}
  </code></pre>