The document discusses various concepts related to entities in Drupal 7 including: 1) Declaring an entity using hook_entity_info() and specifying the controller class. 2) Implementing hook_schema() to define the entity's database table. 3) Additional functionality provided by the Entity API module including entity properties and wrappers. 4) Using the entity class and controller for common operations like loading and saving entities. 5) Performing queries on entity fields using the EntityFieldQuery class.

1. Entities in Drupal 7
Drupalcamp Arad 2012

2. About me
Senior LAMP developer at Pitech+plus
Drupal projects worked on:

http://www.louvre.fr

http://www.cartier.us
Module contributor:
Taxonomy revisions: http://drupal.org/project/taxonomy_revision
Maxlength widget for textareas: http://drupal.org/project/maxlength_js_widget
drupal.org profile:
http://drupal.org/user/350126
IRC nickname: skipyT
Twitter: @ztasnadi

3. Summary

short introduction to entities

declaring an entity

entity API

entity properties

fieldable entities

entity metadata wrappers

entity class and the entity controller

entity field queries

4. Entities
What is an entity?
A data unit!
A data unit which Drupal is aware of!
Stored Anywhere...
Entities in core:
node = entity content type = bundle
taxonomy term = entity vocabulary = bundle
and others like files, vocabularies.

5. Introduction to Entities
All of the entities are:
Loadable
Identifiable
Can be stored anywhere.
Also they can be fieldable.

6. Declaring an entity

Implement hook_entity_info()

Specify the controller class
/**
* Implements hook_entity_info().
*/
function drupalcamp_entity_info() {
$return = array(
'profile' => array(
'label' => t('Profile'),
'entity class' => 'ProfileEntity',
'controller class' => 'EntityAPIController',
'module' => 'drupalcamp',
'base table' => 'profile',

7. Declaring an entity
'access callback' => 'drupalcamp_profile_access',
'bundles' => array(
'profile' => array('label' => 'Profile'),
),
'entity keys' => array(
'id' => 'id',
),
),
);
return $return;
}

8. Declaring an entity
Implement hook_schema()
/**
* Implements hook_schema().
*/
function drupalcamp_product_schema() {
$schema = array();
$schema['profile'] = array(
'description' => "Base table of the profile entity.",
'fields' => array(
'id' => array(
'description' => 'The primary id of a profile.',
'type' => 'serial',
'unsigned' => TRUE,
'not null' => TRUE,
),

9. Declaring an entity
'created' => array(
'description' => 'The Unix timestamp when
the profile was created.',
'type' => 'int',
'not null' => TRUE,
'default' => 0,
),
),
'primary key' => array('id'),
);
return $schema;
}

10. Declaring an entity
And now you can use functions from core like:
entity_load();
entity_get_info();
entity_get_controller();
But this is not enough!
Let's check Entity API...

11. Entity API
Assists us interacting with entities.
entity_create()
entity_access()
entity_view()
entity_save()
entity_delete()
entity_load_single()
entity_get_property_info()
entity_metadata_wrapper()

12. Entity API
Provides a base entity class and a
base entity controller class.
Entity
EntityAPIController
Supports revisions, database
transactions, methods for create,
delete, load, etc.
Provides unified CRUD interface

13. Entity API

14. Fieldable entities

Entities are fieldable if we set:
'fieldable' = TRUE,
//in hook_entity_info()

Bundles are like content types for nodes

Check the entity bundle plugin also:
http://drupal.org/project/entity_bund
le_plugin

15. Entity properties

Unified access to entity data

Validation

Access information
Several contrib modules are using it:

Entity views

Rules

Entity tokens

Search API

WSClient

VBO, OG, Drupal commerce

16. Entity properties
In hook_entity_property_info()
And hook_entity_property_info_alter()
$properties['mail'] = array(
'label' => t("Email"),
'type' => 'text',
'description' => t("The email address of ..."),
'setter callback' => 'entity_property_verbatim_set',
'validation callback' => 'valid_email_address',
'required' => TRUE,
'access callback' => 'user_properties_access',
'schema field' => 'mail',
);

17. Entity properties
Example of entity property use:
/**
* Implements hook_entity_property_info().
*/
function drupalcamp_entity_property_info_alter(&$entity_info)
{
$entity_info['drupalcamp_product_display']['properties']
['sold_online'] = array(
'label' => t('Product sold online'),
'type' => 'list<text>',
'options list' => 'drupalcamp_sold_online_options_list',
'description' => t('A flag indicating whether or not the
product is sold online.'),
'getter callback' => 'drupalcamp_sold_online_getter',
'computed' => TRUE,
);
}

18. Entity wrappers
$wrapper = entity_metadata_wrapper('node', $node);
$mail = $wrapper­>author­>mail­>value();
$wrapper­>author­>mail
­>set('ztasnadi@pitechplus.com');
$text = $wrapper­>field_text­>value();
$wrapper­>language('ro')­>field_text­>value();
$terms = $wrapper­>field_tags­>value();
$wrapper­>field_tags[] = $term;
$options = $wrapper­>field_tags­>optionsList();
$label = $wrapper­>field_tags[0]­>label();
$access = $wrapper­>field_tags­>access('edit');

19. Entity class
We can use the entity class methods
to avoid to introduce new
implementations for:

hook_entity_presave

hook_entity_insert

hook_entity_update

Or to do custom methods like entity
health check, tagging, etc.

20. Entity controller
Example of usage:

During hook_cron we want to update,
touch multiple entities.
Don't forget to call the resetCache
and the mark to reindex if you are
updating the entities. Good example
is when you are enabling several
entities based on their publication
date.

21. Entity field queries
$query = new EntityFieldQuery();
$query­>entityCondition('entity_type', 'profile');
$query­>entityCondition('bundle', 'community_profile');
$query­>entityCondition('id', 2, '<>');
$query­>propertyCondition('created_at',
time() ­ 3600, '<');
$query­>propertyCondition('user_id', $user­>uid);
$query­>fieldCondition('field_taxonomy_category',
'target_id', $term­>tid);
$query­>fieldCondition('field_taxonomy_category',
'target_type', 'watches');
$query­>range(0, 10)
­>addMetaData('account', user_load(1)); // Run the
query as user 1.
// Other methods: count, propertyOrderBy, age
(FIELD_LOAD_CURRENT, FIELD_LOAD_REVISION)

22. Entity field queries
$result = $query­>execute();
if (!empty($result['profile'])) {
$profiles = entity_load('profile',
array_keys($result['profile']));
}
// The above example works only if the $query age
is set to FIELD_LOAD_CURRENT, which is the default
value. For FIELD_LOAD_REVISION the results are
keyed by the revision id.

23. And the guy is Charles Darwin
and not Santa, because we are: