laravel polymorphic pivot table code example

Example 1: has many through laravel

class Country extends Model
{
    public function posts()
    {
        return $this->hasManyThrough(
            'App\Post',
            'App\User',
            'country_id', // Foreign key on users table...
            'user_id', // Foreign key on posts table...
            'id', // Local key on countries table...
            'id' // Local key on users table...
        );
    }
}

when
countries
    id - integer
    name - string

users
    id - integer
    country_id - integer
    name - string

posts
    id - integer
    user_id - integer
    title - string

Example 2: laravel has one through

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Mechanic extends Model
{
    /**
     * Get the car's owner.
     */
    public function carOwner()
    {
        return $this->hasOneThrough('App\Owner', 'App\Car');
    }
}

Example 3: morph relation laravel

You may register the morphMap in the boot function of your 
App\Providers\AppServiceProvider class or create a separate service provider 
if you wish.

use Illuminate\Database\Eloquent\Relations\Relation;

Relation::morphMap([
    'post' => 'App\Models\Post',
    'video' => 'App\Models\Video',
]);