Drupal 7 Module Development

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Chapter 7
Now look at that query again. It's returning three properties, the entity id, revision
id, and bundle name. All entity queries return that same data: the entity type, entity
id, revision id, and bundle. Each record is keyed by its entity id, which in turn is
keyed by the entity type (since it is possible to get back multiple types of entities
in a single query).
Because we know exactly what that structure is, we can leverage it easily. In this
case we want to fully load all artworks that we found, so we run array_keys() on
the $result['artwork'] array, to get an array of just those ids and then load them.
Note that we're using artwork_load_multiple(). Rather than loading each artwork
separately, and running whatever queries are needed to do so, we load them all at
once. That means one or five (or fifty if we were allowing that many) results all take
about the same amount of time to load.
Once we have our artwork objects, we simply get the render array representing each
one using the functionality we build in Chapter 6 and merge them together, then
return the resulting array. When it gets rendered we will see all of our artworks,
one after another.
Now let's make one small change to our field query:
$query = new EntityFieldQuery();
$query
->entityCondition('entity_type', 'artwork')
->propertyOrderBy('created', 'DESC')
->fieldCondition('field_artist', 'value', 'Da Vinci')
->range(0, 5);
$result = $query->execute();
Here, we also filter for just those artworks that have a field named field_artist,
the value column of which is exactly equal to the string Da Vinci. The rest of the
code is the same, but we will now get fewer results. If we assume that everything is
stored in the local SQL database then the query could be something like this:
SELECT field_data_field_artist0.entity_id AS entity_id, field_data_
field_artist0.revision_id AS revision_id, field_data_field_artist0.
bundle AS bundle, fcet.type AS entity_type
FROM
field_data_field_artist field_data_field_artist0
INNER JOIN field_config_entity_type fcet ON fcet.etid = field_data_
field_artist0.etid
INNER JOIN artwork artwork ON artwork.aid = field_data_field_artist0.
entity_id
WHERE (field_data_field_artist0.field_artist_value = 'Da Vinci') AND
(field_data_field_artist0.deleted = 0) AND (fcet.type = 'artwork')
ORDER BY artwork.created DESC
LIMIT 5 OFFSET 0