Drupal 7 Module Development

Working with Content
Once again, our primary means of communicating with Drupal is through large
structured arrays that define all the information we need. In this case, our $return
array has a single entry, artwork. The string artwork, as the top-most key, will serve
as the "machine name" of this entity, which is how it will be referred to in code. The
label key specifies what name should be shown to the user. The base table, revision
table, and object keys entries tell the entity system about how our artwork is going to
be stored, and are used by the default controller:
• The main table where artworks are stored is called artwork, which has a
primary key field (the "id" field) of aid.
• Revisions will be stored in a table called artwork_revision, and the revision's
unique ID is called vid.
• Since we're supporting multiple bundles, we also tell the system what field
will indicate to which bundle a given artwork belongs. In this case, we use
the type field.
• The human-readable name of a given artwork is stored in the title field.
The view modes key defines the different ways that our entity can be viewed. In this
case we are defining a "full" version and a "teaser" version, just as nodes use, but
we could define whatever view modes we wanted. Other modules are free to inject
additional view modes via hook_entity_info_alter() as well. As usual, the key of
the view modes array is the machine name of the view mode and the label property
is the human-friendly name. The custom settings flag indicates whether or not the
Field UI should allow field formatters to be configured separately for that view mode
by default. It is easily changed via the UI.
We also define a uri_callback function, namely artwork_uri(). That allows us
to abstract out the definition of the path within Drupal where this artwork will be
accessed. Instead of hard coding a path, such as artwork/$aid, we call a callback
function to generate it for us. That is most important when listing entities of different
types, as we can simply call a single function, entity_uri($type, $entity), and
get back the correct information to pass to the url() or l() functions. Our simple
callback looks like this:
function artwork_uri($artwork) {
return array(
'path' => 'artwork/' . $artwork->aid,
);
}
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