SQL 1005 error when running Laravel 4 migration

Question

I'm trying to set up a comments table with a foreign key to the users table with Laravel 4's schema builder, like so:

Schema::create('comments', function(Blueprint $table)
{
    $table->increments('id');
    $table->integer('user_id');
    $table->text('body');
    $table->timestamps();

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

But when I run the migration, I get the following error message:

[Exception]
SQLSTATE[HY000]: General error: 1005 Can't create table 'streamr.#sql-16fc_89' (errno: 150)
(SQL: alter table `comments` add constraint comments_user_id_foreign foreign key (`user_id`) references `users` (`id`)) (Bindings: array ())

As far as I can tell, this is because the id column of the users table is int(10), and $table->integer('user_id') makes an int(11) column causing the foreign key to fail due to incompatible column types. However, when I try to set the length of the integer column I'm creating it doesn't work:

$table->integer('user_id', 10);

Is there any way to get around this? Seems strange to me that Laravel's schema builder will build a int(10) column for primary keys and not make them compatible with integer columns :/

Edit: I've also made sure the tables are InnoDB, and they are.

Answer 1

$table->increments('id') produces an unsigned integer. Integers are not compatible with unsigned integers when setting up a foreign key.

Try this:

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

From laravel docs (http://laravel.com/docs/schema#foreign-keys):

Note: When creating a foreign key that references an incrementing integer, remember to always make the foreign key column unsigned.