フィールドAPI　データー構造

Field APIのフィールド及びインスタンスについての説明です

フィールドAPIは2つの主要なデータ構造、フィールドおよびインスタンス、およびバンドルの概念を定義します。フィールドは、エンティティに加えることが出来る特別のタイプのデータを定義します。フィールドインスタンスは単一のバンドルに加えられたフィールドです。バンドルは、フィールドアタッチAPIによってグループと見なされる、1セットのフィールドで、単一のフィールド化可能なエンティティータイプと関連しています。

For example, suppose a site administrator wants Article nodes to　have a subtitle and photo. Using the Field API or Field UI module,
the administrator creates a field named 'subtitle' of type 'text'　and a field named 'photo' of type 'image'. The administrator(again, via a UI) creates two Field Instances, one attaching the　field 'subtitle' to the 'node' bundle 'article' and one attaching　the field 'photo' to the 'node' bundle 'article'. When the node　system uses the Field Attach API to load all fields for an Article　node, it passes the node's entity type (which is 'node') and
content type (which is 'article') as the node's bundle.　field_attach_load() then loads the 'subtitle' and 'photo' fields　because they are both attached to the 'node' bundle 'article'.

Field definitions are represented as an array of key/value pairs.

@param array $field:

• id (integer, read-only)
  The primary identifier of the field. It is assigned automatically
  by field_create_field().
• field_name (string)
  The name of the field. Each field name is unique within Field API.　When a field is attached to an entity, the field's data is stored　in $entity->$field_name. Maximum length is 32 characters.
• type (string)
  The type of the field, such as 'text' or 'image'. Field types　are defined by modules that implement hook_field_info().
• entity_types (array)
  The array of entity types that can hold instances of this field. If　empty or not specified, the field can have instances in any entity type.
• cardinality (integer)
  The number of values the field can hold. Legal values are any　positive integer or FIELD_CARDINALITY_UNLIMITED.
• translatable (integer)
  Whether the field is translatable.
• locked (integer)
  Whether or not the field is available for editing. If TRUE, users can't　change field settings or create new instances of the field in the UI.
  Defaults to FALSE.
• module (string, read-only)
  The name of the module that implements the field type.
• active (integer, read-only)
  TRUE if the module that implements the field type is currently　enabled, FALSE otherwise.
• deleted (integer, read-only)
  TRUE if this field has been deleted, FALSE otherwise. Deleted　fields are ignored by the Field Attach API. This property exists　because fields can be marked for deletion but only actually　destroyed by a separate garbage-collection process.
• columns (array, read-only).
  An array of the Field API columns used to store each value of　this field. The column list may depend on field settings; it is　not constant per field type. Field API column specifications are　exactly like Schema API column specifications but, depending on　the field storage module in use, the name of the column may not　represent an actual column in an SQL database.
• indexes (array).
  An array of indexes on data columns, using the same definition format　as Schema API index specifications. Only columns that appear in the
  'columns' setting are allowed. Note that field types can specify　default indexes, which can be modified or added to when　creating a field.
• foreign keys: (optional) An associative array of relations, using the same
  structure as the 'foreign keys' definition of hook_schema(). Note, however,
  that the field data is not necessarily stored in SQL. Also, the possible
  usage is limited, as you cannot specify another field as related, only
  existing SQL tables, such as filter formats.
• settings (array)
  A sub-array of key/value pairs of field-type-specific settings. Each
  field type module defines and documents its own field settings.
• storage (array)
  A sub-array of key/value pairs identifying the storage backend to use for
  the for the field.
  • type (string)
    The storage backend used by the field. Storage backends are defined
    by modules that implement hook_field_storage_info().
  • module (string, read-only)
    The name of the module that implements the storage backend.
  • active (integer, read-only)
    TRUE if the module that implements the storage backend is currently
    enabled, FALSE otherwise.
  • settings (array)
    A sub-array of key/value pairs of settings. Each storage backend
    defines and documents its own settings.

Field instance definitions are represented as an array of key/value pairs.

@param array $instance:

• id (integer, read-only)
  The primary identifier of this field instance. It is assigned
  automatically by field_create_instance().
• field_id (integer, read-only)
  The foreign key of the field attached to the bundle by this instance.
  It is populated automatically by field_create_instance().
• field_name (string)
  The name of the field attached to the bundle by this instance.
• entity_type (string)
  The name of the entity type the instance is attached to.
• bundle (string)
  The name of the bundle that the field is attached to.
• label (string)
  A human-readable label for the field when used with this
  bundle. For example, the label will be the title of Form API
  elements for this instance.
• description (string)
  A human-readable description for the field when used with this
  bundle. For example, the description will be the help text of
  Form API elements for this instance.
• required (integer)
  TRUE if a value for this field is required when used with this
  bundle, FALSE otherwise. Currently, required-ness is only enforced
  during Form API operations, not by field_attach_load(),
  field_attach_insert(), or field_attach_update().
• default_value_function (string)
  The name of the function, if any, that will provide a default value.
• default_value (array)
  If default_value_function is not set, then fixed values can be provided.
• deleted (integer, read-only)
  TRUE if this instance has been deleted, FALSE otherwise.
  Deleted instances are ignored by the Field Attach API.
  This property exists because instances can be marked for deletion but
  only actually destroyed by a separate garbage-collection process.
• settings (array)
  A sub-array of key/value pairs of field-type-specific instance
  settings. Each field type module defines and documents its own
  instance settings.
• widget (array)
  A sub-array of key/value pairs identifying the Form API input widget
  for the field when used by this bundle.
  • type (string)
    The type of the widget, such as text_textfield. Widget types
    are defined by modules that implement hook_field_widget_info().
  • settings (array)
    A sub-array of key/value pairs of widget-type-specific settings.
    Each field widget type module defines and documents its own
    widget settings.
  • weight (float)
    The weight of the widget relative to the other elements in entity
    edit forms.
  • module (string, read-only)
    The name of the module that implements the widget type.
• display (array)
  A sub-array of key/value pairs identifying the way field values should
  be displayed in each of the entity type's view modes, plus the 'default'
  mode. For each view mode, Field UI lets site administrators define
  whether they want to use a dedicated set of display options or the
  'default' options to reduce the number of displays to maintain as they
  add new fields. For nodes, on a fresh install, only the 'teaser' view
  mode is configured to use custom display options, all other view modes
  defined use the 'default' options by default. When programmatically
  adding field instances on nodes, it is therefore recommended to at least
  specify display options for 'default' and 'teaser'.
  • default (array)
    A sub-array of key/value pairs describing the display options to be
    used when the field is being displayed in view modes that are not
    configured to use dedicated display options.
    • label (string)
      Position of the label. 'inline', 'above' and 'hidden' are the
      values recognized by the default 'field' theme implementation.
    • type (string)
      The type of the display formatter, or 'hidden' for no display.
    • settings (array)
      A sub-array of key/value pairs of display options specific to
      the formatter.
    • weight (float)
      The weight of the field relative to the other entity components
      displayed in this view mode.
      • module (string, read-only)
        The name of the module which implements the display formatter.
  • some_mode
    A sub-array of key/value pairs describing the display options to be
    used when the field is being displayed in the 'some_mode' view mode.
    Those options will only be actually applied at run time if the view
    mode is not configured to use default settings for this bundle.
    • ...
  • other_mode
    • ...

Bundles are represented by two strings, an entity type and a bundle name.