Entities, Bundles,Fields and Field instance

Entities

An<wbr><em>entity</em><wbr>is an abstractdata type in drupal. An<wbr><em>Entitytype</em><wbr>is required to implementthe<wbr><em>Entity</em><wbr>interfaces asdefined in the core Entity API. It is a generalisation of the node,comment, user, taxonomy term types of previous versions of Drupal.In Drupal 7, only the R from CRUD is specified in core, but work isunderway to fill the gap in next versions. There is acontributed<wbr><a href="http://dikini.net/31.08.2010/entities_bundles_fields_and_field_instances#entity_api">Entity APImodule</a>, which aims to do it. Entities can havemultiple<wbr><em><a href="http://dikini.net/31.08.2010/entities_bundles_fields_and_field_instances#bundles" title="Bundles definition">bundles</a></em></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

Bundles

Bundles are groups of fields. A bundle is a specialisation, aninstance of an<wbr><em><a href="http://dikini.net/31.08.2010/entities_bundles_fields_and_field_instances#entities">entity</a></em>. Ifnode is an<wbr><em>entity</em>, then an article isan<wbr><em>bundle</em>. This allows distinguishing thekinds and types within the system - kinds classify types, typesclassify values (concrete objects)</wbr></wbr></wbr>

Fields

Fields<wbr>are the incarnation of the CCKdata type of the same name moved to Drupal core. What are they? Theanswer can be found by reading<wbr><a href="http://api.drupal.org/api/group/field/7" title="Field Api">Field Api</a>. Inessence, a<wbr><em>field</em><wbr>is aprimitive drupal data type implementing the interface described inthose pages. Fields have an associated schema, formatter(s),widget(s) and settings. Example field types - file field, textfield, etc... Modules can define new field types.</wbr></wbr></wbr></wbr>

Field Instances

A<wbr><em>Field Instance</em><wbr>is aconcrete specialisation of a<wbr><a href="http://dikini.net/31.08.2010/entities_bundles_fields_and_field_instances#fields"><em>fieldtype</em></a>. It captures the field type together with itsconfiguration - schema, formatter and widget. Field instances areattached to bundles.</wbr></wbr></wbr>

Fieldable objects

The term is sometimes used for<wbr><a href="http://dikini.net/31.08.2010/entities_bundles_fields_and_field_instances#entity">entities</a><wbr>andbundles.</wbr></wbr>