BadMethodCallException in Macroable.php line 74: Method specialization does not exist

I am getting this small issue. Below is the source code

Doctor Model: class Doctor extends Model { ...... .... public function specialization() { return $this->HasMany('App\Specialization'); } } Specialization Model:
class Specialization extends Model { ...... .... public function doctor () { return $this->belongsTo('App\Doctor', 'id'); } }

Specialization Model:
Here the spec_id is a foreign key class DoctorController extends Controller { ...... .... //Create a Doctor public function createDoctor(Request $request) { $doctor = new Doctor(); $doctor->doctor_id = $request->input('doctor_id'); // $doctor->spec_id = $request->input('spec_id'); $doctor->spec_id = $request->specialization()->id; $doctor->dob = $request->input('dob'); $doctor->age = $request->input('age'); $doctor->gender = $request->input('gender'); $doctor->qualification = $request->input('qualification'); $doctor->experience = $request->input('experience'); $doctor->phone_number = $request->input('phone_number'); // $doctor->email = $request->user()->email; $doctor->email = $request->input('email'); // $doctor->user_id = $request->user()->user_id; $doctor->user_id = $request->input('user_id'); $doctor->save(); return response()->json(['doctor' => $doctor], 201); } } Please let me know how do i fix it.

via Chebli Mohamed