Sub-Modules

When to Use

You need extended functionality like GraphQL, JSON:API normalization, Entity Browser, Linkit, Media Library, Search API, Single Directory Component rendering, or AI integration. Nine sub-modules ship with 5.x.

All sub-modules declare core_version_requirement: ^11.4 || ^12 in 5.x.

custom_field_graphql

GraphQL Compose integration with 11 schema type plugins.

Dependencies: graphql_compose -- unversioned in .info.yml; upstream tests against 2.4.x-dev
Schema types: CustomFieldType, CustomFieldImage, CustomFieldFile, CustomFieldEntityReference, CustomFieldLinkType, CustomFieldUriType, CustomFieldLinkAttributesType, CustomFieldDateRange, CustomFieldTimeRange, CustomFieldViewfield, CustomFieldViewfieldSchemaExtension
Exposes custom fields to GraphQL API automatically

custom_field_jsonapi

JSON:API normalizers for custom field types.

Dependencies: jsonapi (core)
Normalizers: 6 classes -- DateRange, DateTime, EntityReference, StringLong, TimeRange, Uri
Automatically normalizes custom field data in JSON:API responses

custom_field_entity_browser

Entity Browser widget for entity reference columns.

Dependencies: entity_browser
Plugin: EntityReferenceBrowserWidget
Visual entity browser instead of autocomplete for entity reference columns

custom_field_linkit

Linkit autocomplete widgets for link and uri columns.

Dependencies: linkit:linkit, unversioned in .info.yml; composer.json require-dev pins ^7 only -- 6.x support was dropped
Plugins: LinkitWidget, LinkitUrlWidget, plus the LinkitFormatter and LinkitUrlFormatter sub-field formatters
Linkit autocomplete for internal link selection in link columns, and matching output formatters

custom_field_media

Media library widget for image columns.

Dependencies: drupal:media_library (core) -- the media_library module, not media alone
Select existing media entities instead of direct file upload

custom_field_search_api

Search API integration.

Dependencies: search_api
Index and search custom field columns

custom_field_viewfield

Viewfield type for embedding views in custom fields.

Dependencies: None
Type: viewfield (embed view displays)
Extended properties: field__display, field__arguments, field__items

custom_field_ai

AI module integration.

Dependencies: ai:ai (>= 1.3) in .info.yml; require-dev ^1.3
AI-powered field processing

custom_field_sdc

Renders a whole view mode through a Single Directory Component.

Dependencies: none beyond core SDC
Contents: two hook classes and a config-schema file -- src/Hook/FormHooks.php (adds the component/prop/slot settings to the entity view display form as a custom_field_sdc third-party setting) and src/Hook/EntityHooks.php (hook_entity_view_alter(), which replaces the entity build with the configured component, and bails out if sdc_display has claimed the display). No plugin classes.
Not here: the custom_field_sdc field-level formatter (SingleDirectoryComponentFormatter) lives in the main module and works without this sub-module. The shared plugin ID makes them easy to confuse.
An alternative to the sdc_display contrib module for component-driven output of whole view modes
Full treatment: SDC View-Mode Rendering -- the mechanism, the config shape, the fail-safes, and when to pick it over UI Patterns or Canvas

Common Mistakes

Enabling unnecessary sub-modules -- Only enable modules for integrations you actually use
Not configuring Linkit profiles -- LinkitWidget requires configured Linkit profile to work
Expecting auto-indexing -- Search API sub-module provides types; you must configure index fields