Drupal 7 Module Development

Working with Content
'default' => '',
),
'created' => array(
'description' =>
'The Unix timestamp when the artwork was created.',
'type' => 'int',
'not null' => TRUE,
'default' => 0,
),
'changed' => array(
'description' =>
'The Unix timestamp when the artwork was most recently saved.',
'type' => 'int',
'not null' => TRUE,
'default' => 0,
),
),
'unique keys' => array(
'aid_vid' => array('aid', 'vid'),
'aid' => array('aid')
),
'primary key' => array('aid'),
);
}
return $schema;
That looks like a lot of code, but it's really just another big Drupal array. The keys of
the $schema array are the names of tables to be created. Each table is then defined as
another nested array that defines the fields, indices, and other data about the table.
Most are self-explanatory.
See http://drupal.org/node/146843 for more information
on the Schema API.
Note that we're using an integer field called aid for our primary key. We also store
the bundle that an artwork belongs to in a column called type (just like nodes),
and we have a "version ID" field called vid. All entities can support versioning in a
similar fashion to nodes, so let's build that in from the start.
To store old revisions, we'll need another table as well. We'll call that table
artwork_revision:
$schema['artwork_revision'] = array(
'description' =>
'Stores information about each saved version of an {artwork}.',
[ 154 ]