Implement a storage engine for Field API data.
The Field Attach API uses the Field Storage API to perform all "database access". Each Field Storage API hook function defines a primitive database operation such as read, write, or delete. The default field storage module, field_sql_storage.module, uses the local SQL database to implement these operations, but alternative field storage backends can choose to represent the data in SQL differently or use a completely different storage mechanism such as a cloud-based database.
Each field defines which storage backend it uses. The Drupal system variable 'field_storage_default' identifies the storage backend used by default.
See Field API for information about the other parts of the Field API.
field/ field.attach.inc, line 32
- Field attach API, allowing entities (nodes, users, ...) to be 'fieldable'.
||Write field data for an entity.|
||Act on creation of a new field.|
||Delete all field data for an entity.|
||Act on deletion of a field.|
||Act on deletion of a field instance.|
||Delete a single revision of field data for an entity.|
||Reveal the internal details about the storage for a field.|
||Perform alterations on Field API storage details.|
||Expose Field API storage backends.|
||Perform alterations on Field API storage types.|
||Load field data for a set of entities.|
||Act before the storage backends insert field data.|
||Act before the storage backends load field data.|
||Act before the storage backends update field data.|
||Remove field storage information when field data is purged.|
||Remove field storage information when a field record is purged.|
||Remove field storage information when a field instance is purged.|
||Execute an EntityFieldQuery.|