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.
Constants
| Name | Description |
|---|---|
| FIELD_STORAGE_INSERT | Argument for an insert operation. |
| FIELD_STORAGE_UPDATE | Argument for an update operation. |
Functions & methods
| Name | Description |
|---|---|
| hook_field_display_alter | Alters the display settings of a field before it gets displayed. |
| hook_field_display_ENTITY_TYPE_alter | Alters the display settings of a field on a given entity type before it gets displayed. |
| hook_field_extra_fields_display_alter | Alters the display settings of pseudo-fields before an entity is displayed. |
| hook_field_info_max_weight | Returns the maximum weight for the entity components handled by the module. |
| hook_field_storage_create_field | Act on creation of a new field. |
| hook_field_storage_delete | Delete all field data for an entity. |
| hook_field_storage_delete_field | Act on deletion of a field. |
| hook_field_storage_delete_instance | Act on deletion of a field instance. |
| hook_field_storage_delete_revision | Delete a single revision of field data for an entity. |
| hook_field_storage_details | Reveal the internal details about the storage for a field. |
| hook_field_storage_details_alter | Perform alterations on Field API storage details. |
| hook_field_storage_info | Expose Field API storage backends. |
| hook_field_storage_info_alter | Perform alterations on Field API storage types. |
| hook_field_storage_load | Load field data for a set of entities. |
| hook_field_storage_pre_insert | Act before the storage backends insert field data. |
| hook_field_storage_pre_load | Act before the storage backends load field data. |
| hook_field_storage_pre_update | Act before the storage backends update field data. |
| hook_field_storage_query | Execute an EntityFieldQuery. |
| hook_field_storage_write | Write field data for an entity. |
| hook_field_widget_properties_alter | Alters the widget properties of a field instance before it gets displayed. |
| hook_field_widget_properties_ENTITY_TYPE_alter | Alters the widget properties of a field instance on a given entity type before it gets displayed. |
File
- modules/
field/ field.attach.inc, line 32 - Field attach API, allowing entities (nodes, users, ...) to be 'fieldable'.