Answers for "how to set foreign key in laravel"

foreign key in laravel migration

$table->unsignedBigInteger('user_id');
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');

add foreign key column laravel 5.8

update your `integer('user_id')` to `bigInteger('user_id')`
public function up() { 
        Schema::create('evaluation', function (Blueprint $table) { 
            $table->increments('id'); 
            $table->bigInteger('user_id')->unsigned()->index(); 
            $table->timestamps();
            $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
        });
    }

foreign key string laravel

Schema::table('portfolios', function (Blueprint $table) {
            $table->string('filter_alias');
            $table->foreign('filter_alias')->cascadeOnDelete()->references('alias')->on('filters');
        });