Q:

Laravel migration with foreign key drops 1064 error

I spent already hell of a lot of time but still doesn't work my migration with foreign keys alter. I get 
[Illuminate\Database\QueryException]                                                 
  SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your S  
  QL syntax; check the manual that corresponds to your MySQL server version for the r  
  ight syntax to use near '1' at line 1 (SQL: alter table `posts` add constraint post  
  s_author_foreign foreign key (`author`) references `users` (`id`) on delete 1)       

the class what I try to migrate look like
<?php

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

class CreatePostsTable extends Migration {

    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up() {
        if (!Schema::hasTable('posts')) {
            Schema::create('posts', function($table) {

                $table->engine = 'InnoDB';

                $table->increments('id');
                $table->string('title', 255);
                $table->string('slug', 255);
                $table->unique('slug');
                $table->string('type', 255);
                $table->text('content');
                $table->integer('parent');
                $table->integer('author')->unsigned();
                $table->string('avatar', 255);
                $table->string('guid', 255);
                $table->string('mime_type', 255);
                $table->integer('menu_order');
                $table->boolean('status');
                $table->index('id');
                $table->timestamps();
            });

            Schema::table('posts', function($table) {
                $table->foreign('author')->references('id')->on('users')->onDelete();
            });

        }
    }

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

}

what is wrong in my migration?

A:

The error says it all.
Maybe you wanted this:
$table->foreign('author')->references('id')->on('users')->onDelete();

to be: 
$table->foreign('author')->references('id')->on('users')->onDelete('cascade');

or maybe simply:
$table->foreign('author')->references('id')->on('users');

See the documentations here.

