Answers for "how to get old value in laravel 8 foreign values"

foreignId in laravel

// for laravel 7 or above. 
$table->foreignId('user_id')->constrained();
/*-----------OR---------------*/
$table->foreignId('user_id')->constrained('users');

laravel 8 foreign key migration

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

Schema::table('posts', function (Blueprint $table) {
    $table->unsignedBigInteger('user_id');

    $table->foreign('user_id')->references('id')->on('users');
});