Impossible d'obtenir la valeur de l'entrée de la forme à l'intérieur de l'angulaire 8

J'ai une forme simple dans la page HTML. Maintenant, il s'agit d'un formulaire "add-edit", alors quand j'ouvre la page avec un ID, je devrais compiler toutes les entrées avec les valeurs objecid, lorsque j'ouvre la page sans id ID, je devrais pouvoir compiler toutes les entrées manuellement et Ajoutez ensuite l'objet à la base de données. Le problème est que je ne peux pas lire / écrire la valeur du champ INPUTS à l'aide de:

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, Validators, FormControl } from '@angular/forms';
import { Router, ActivatedRoute } from '@angular/router';
import { FuelService } from '../services/fuel.service';
import { VehiclesService } from '../services/vehicles.service';
import { Fuel } from '../models/fuel';
import { Vehicle } from '../models/vehicle';
import { of } from 'rxjs';

@Component({
  selector: 'app-fuel-add-edit',
  templateUrl: './fuel-add-edit.component.html',
  styleUrls: ['./fuel-add-edit.component.css']
})
export class FuelAddEditComponent implements OnInit {

  form: FormGroup;
  plateCtrl: FormControl;
  actionType: string;
  fuelId: number;
  errorMessage: any;
  existingFuel: Fuel;
  vehicles: Vehicle[];
  dataSelected: Date;

  constructor(private fuelService: FuelService, private vehicleService: VehiclesService, private formBuilder: FormBuilder, private avRoute: ActivatedRoute, private router: Router) {
    const idParam = 'id';
    this.actionType = 'Add';
    if (this.avRoute.snapshot.params[idParam]) {
      this.fuelId = this.avRoute.snapshot.params[idParam];
    }

    this.form = this.formBuilder.group(
      {
        picker: [''],
        cost: ['', [Validators.required]],
        vehicleList: [''],
        startKm: ['', [Validators.required]],
        endKm: ['', [Validators.required]],
        liter: ['', [Validators.required]],
        average: ['', [Validators.required]]
      }
    )

    of(this.vehicleService.getVehicles().subscribe(data=> (
      this.vehicles = data
    )))

  }

  ngOnInit() {
    if (this.fuelId > 0) {
      console.log(this.form);
      this.actionType = "Edit";
      this.fuelService.getFuel(this.fuelId)
        .subscribe(data => (
          this.existingFuel = data,
          this.form.get["picker"].setValue(data.date),
          this.form.get["cost"].setValue(data.cost),
          this.form.get["vehicleList"].setValue(data.vehicle.id),
          this.form.get["startKm"].setValue(data.startKm),
          this.form.get["endKm"].setValue(data.endKm),
          this.form.get["liter"].setValue(data.liter),
          this.form.get["average"].setValue(data.average)
        ));
    }
  }

  get picker() { return this.form.get("picker"); }
  get cost() { return this.form.get("cost"); }
  get vehicleList() { return this.form.get("vehicleList"); }
  get startKm() { return this.form.get("startKm"); }
  get endKm() { return this.form.get("endKm"); }
  get liter() { return this.form.get("liter"); }
  get average() { return this.form.get("average"); }
}