Annotation Interface HandleDocument

@Documented @Retention(RUNTIME) @Target({METHOD,CONSTRUCTOR}) @HandleMessage(DOCUMENT) public @interface HandleDocument
Marks a method or constructor as a handler for document messages within a search collection.

This is a specialization of HandleMessage for MessageType.DOCUMENT messages. It allows consuming updates from the document store in near real-time—similar to event tracking. Handlers can either specify a collection name or a document class, or infer a Model node or logical Graph from the handler parameter.

Document Tracking Semantics

Each time a document is (re)indexed in Fluxzero, it receives a new tracking index. When a handler is subscribed via @HandleDocument, it will receive the most recent version of the document for each index. If the tracker is behind (e.g., during a replay), earlier versions of the same document may be skipped—only the latest version is retained.

Transforming and Updating Documents

A powerful feature of document handlers is that they can return a modified version of the document to update it in-place. This allows document transformations and upcasting to be applied automatically and reliably.

For this behavior to take effect:

  • The returned document must have a higher Revision than the one stored
  • The updated version will be stored in the document collection under the same ID

Independent Model values use the stricter schema-only contract described by source(). This mechanism supports fully-automated data migrations: handlers can evolve or patch documents over time, and changes are persisted across application restarts.

See Also:

  • Element Details

    • onMissingProtectedData

      MissingProtectedDataPolicy onMissingProtectedData
      Determines how the handler responds when referenced protected data is no longer available.
      Default:
      DEFAULT

    • value

      String value
      Optional name of the document collection. If provided, documentClass() is ignored.

      If neither documentClass nor value are specified, the first parameter of the method is used to determine the collection: 

      class OrganisationHandler {
    @HandleDocument
    void on(Organisation organisation, Metadata metadata) { ... }
}
      See Also:
      Default:
      ""

    • documentClass

      Class<?> documentClass
      Optional class of the documents to handle. If annotated with Searchable, the annotation defines the collection; otherwise the class name is used.

      If neither documentClass nor value are specified, the first parameter of the method is used to determine the collection: 

      class OrganisationHandler {
    @HandleDocument
    void on(Organisation organisation, Metadata metadata) { ... }
}
      See Also:
      Default:
      java.lang.Void.class

    • source

      DocumentSource source
      Document source to observe. DocumentSource.SEARCH is the default: a Model parameter selects its canonical searchable node, and Graph<Model> selects that root and its included descendants. Ancestor content alone does not trigger the latter. Graph handling works with every projection mode; NONE composes the latest indexed nodes when reading an update and does not retain previous Graph snapshots.

      DocumentSource.MODEL_STATE explicitly selects maintained internal Model state for observation or schema migration, including non-searchable DOCUMENT Models. It requires a Model value, not a Graph, and cannot be combined with an explicit collection. There is no automatic fallback between sources.

      Returning an injected Model value may persist a higher-revision schema upcast, but must preserve identity and business state. Use Model commands for business changes. Returning a stored Graph can migrate only its aggregate projection under a concurrency guard; returning a live Graph never writes its nodes. A void handler only observes. Neither route creates historical Graph snapshots that the selected storage does not maintain.

      Default:
      SEARCH

    • disabled

      boolean disabled
      If true, disables this handler during discovery.
      Default:
      false