Start variables with data from an Input

Thanks for your answers ... I add my code as an example

MY CONTROLLER

survey: any [] = [];

constructor (public navCtrl: NavController,               public navParams: NavParams,               public userService: UserProvider,               public toastCtrl: ToastController,               public http: Http,) {

this.http; Http;

this.encuesta['idencuesta'] = '';

this.http.get(url).subscribe(data =>{
  //console.log(data.json())
  this.lists = data.json();//Esto es de otro arreglo :d
  console.log(this.lists['registros']);//Esto es de otro arreglo :d

}, error=> {
  console.log(error.json());
});

}

voteYes () {

let data = new URLSearchParams();

data.append('encuesta[idCiudadano]', this.encuesta['idCiudadano']);
data.append('encuesta[idencuesta]', this.encuesta['idencuesta']);

  this.http.post(url, data)
   .subscribe(data =>{
   },error =>{
     console.log(error.json());
   })

}

VISTA   

In the view Basically, I put an input with the id of a survey, to know which poll is going to vote. In the Controller with the Append I recover that data (idencuesta) that is going away to vote. It is there, where the error jumps .. that the variable is initialized as empty and in the input it is defined with a value.

I more or less understood your question, you should document it a bit more to be able to understand you

What I understood is that you want to define an array and then fill it with even data so you should define the array with all fields (just before the constructor)

something like that

  public Form = {
        campo1:"",
        campo2:"",
        campo3:"",
        campo4:"",
        
   };

If you are going to fill the array with data in the constructor you should use

this.Form.campo1 = "El valor que le quiero asignar ";

if you want to fill them in from an input

<ion-item>
          <ion-label color="primary">campo1 </ion-label>
          <ion-input placeholder="escriba el valor" name="campo1" [(ngModel)]="Form.campo1" ></ion-input>
</ion-item>