cssd-back/database/migrations/2019_04_11_105658_create_uploadables_table.php

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateUploadablesTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('uploadables', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->unsignedBigInteger('uploadable_id');
            $table->string('uploadable_type');
            $table->unsignedBigInteger('gallery_id');
            $table->foreign('gallery_id')->references('id')->on('galleries');
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('uploadables');
    }
}