How to store data in foreign key of a user table - laravel

Question

The question is pretty simple. I am storing user's form data into table. I am using Auth login system of laravel, when user fill the input fields and register all values received in array called $data in create function (as you know code written in laravel as default) but when I save it in table, all values save expect department_id that is a foreign key. There is also a candidate_id and it is also a foreign key of candidate_table and it also save, but department_id have some issue.
Blade
#extends('layouts.app')
#section('content')
<div class="container">
<div class="row">
<div class="col-md-8 col-md-offset-2">
<div class="panel panel-default">
<div class="panel-heading">Register</div>
<div class="panel-body">
<form class="form-horizontal" method="POST" action="{{ route('register') }}">
{{ csrf_field() }}
{{--<input style="text-transform: capitalize;" id="test" type="number" class="form-control" name="id" required autofocus>--}}
<div class="form-group{{ $errors->has('name') ? ' has-error' : '' }}">
<label for="name" class="col-md-4 control-label">Name</label>
<div class="col-md-6">
<input style="text-transform: capitalize;" id="name" type="text" class="form-control" name="name" value="{{ old('name') }}" required autofocus>
#if ($errors->has('name'))
<span class="help-block">
<strong>{{ $errors->first('name') }}</strong>
</span>
#endif
</div>
</div>
<div class="form-group{{ $errors->has('email') ? ' has-error' : '' }}">
<label for="email" class="col-md-4 control-label">E-Mail Address</label>
<div class="col-md-6">
<input id="email" type="email" class="form-control" name="email" value="{{ old('email') }}" required>
#if ($errors->has('email'))
<span class="help-block">
<strong>{{ $errors->first('email') }}</strong>
</span>
#endif
</div>
</div>
<div class="form-group{{ $errors->has('password') ? ' has-error' : '' }}">
<label for="password" class="col-md-4 control-label">Password</label>
<div class="col-md-6">
<input id="password" type="password" class="form-control" name="password" required>
#if ($errors->has('password'))
<span class="help-block">
<strong>{{ $errors->first('password') }}</strong>
</span>
#endif
</div>
</div>
<div class="form-group">
<label for="password-confirm" class="col-md-4 control-label">Confirm Password</label>
<div class="col-md-6">
<input id="password-confirm" type="password" class="form-control" name="password_confirmation" required>
</div>
</div>
<input style="text-transform: capitalize;" id="department" type="number" class="form-control" name="department" required autofocus>
<div class="form-group">
<div class="col-md-6 col-md-offset-4">
<button type="submit" class="btn btn-primary">
Register
</button>
</div>
</div>
</form>
</div>
</div>
</div>
</div>
</div>
#endsection
User Model
<?php
namespace App;
use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;
class User extends Authenticatable
{
public function candidate()
{
return $this->belongsTo(Candidate::class,'candidate_id');
}
public function department()
{
return $this->belongsTo(Department::class,'department_id');
}
use Notifiable;
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = [
'name','email','password','image','candidate_id'
];
/**
* The attributes that should be hidden for arrays.
*
* #var array
*/
protected $hidden = [
'password', 'remember_token',
];
}
Controller
<?php
namespace App\Http\Controllers\Auth;
use App\Department;
use App\User;
use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Validator;
use Illuminate\Foundation\Auth\RegistersUsers;
class RegisterController extends Controller
{
/*
|--------------------------------------------------------------------------
| Register Controller
|--------------------------------------------------------------------------
|
| This controller handles the registration of new users as well as their
| validation and creation. By default this controller uses a trait to
| provide this functionality without requiring any additional code.
|
*/
use RegistersUsers;
/**
* Where to redirect users after registration.
*
* #var string
*/
protected $redirectTo = '/home';
/**
* Create a new controller instance.
*
* #return void
*/
public function __construct()
{
$this->middleware('guest');
}
/**
* Get a validator for an incoming registration request.
*
* #param array $data
* #return \Illuminate\Contracts\Validation\Validator
*/
protected function validator(array $data)
{
return Validator::make($data, [
'name' => 'required|string|max:255',
'email' => 'required|string|email|max:255|unique:users',
'password' => 'required|string|min:6|confirmed',
]);
}
/**
* Create a new user instance after a valid registration.
*
* #param array $data
* #return \App\User
*/
protected function create(array $data)
{
return User::create([
'name' => $data['name'],
'email' => $data['email'],
// 'candidate_id' => $data['id'],
'password' => bcrypt($data['password']),
'department_id' => $data['department'],
]);
}
}

Answer 1

As you can see, for department_id input you have commented out form input field.
{{--<input style="text-transform: capitalize;" id="test" type="number" class="form-control" name="id" required autofocus>--}}
Uncomment the code and it will work fine.
And because of it, it will not store department_id

Answer 2

Try changing...
protected $fillable = [
'name','email','password','image','candidate_id'
];
to
protected $fillable = [
'name','email','password','image','candidate_id','department_id'
];