cis-rest-api/app/Championship.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Championship extends Model
{

    protected $fillable = ['title', 'from_date', 'to_date', 'month', 'year', 'expert', 'competence', 'city', 'location', 'group', 'status'];

    public function expert()
    {
        return $this->hasOne(User::class, 'id', 'expert');
    }

    public function competence()
    {
        return $this->hasOne(Competence::class, 'number', 'competence');
    }

    public function competences()
    {
        return $this->hasOne(Competence::class, 'number', 'competence');
    }

    public function month()
    {
        return $this->hasOne(Month::class, 'id', 'month');
    }

    public function months()
    {
        return $this->hasOne(Month::class, 'id', 'month');
    }

    public function modules()
    {
        return $this->hasMany(Module::class, 'championship', 'id');
    }

    public function members()
    {
        return $this->hasMany(Member::class, 'championship', 'id');
    }

    public function experts()
    {
        return $this->hasMany(Expert::class, 'champ_id', 'id');
    }

    public function cities()
    {
        return $this->hasOne(City::class, 'id', 'city');
    }
}