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.

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

Ordinary document replacements preserve all metadata embedded in the handled stored version, including when the payload was upcast. Tracking-envelope metadata is not copied into the document. Return a Message to replace the complete document metadata explicitly; empty metadata removes it. Only the returned Message's payload and metadata participate in document replacement; its message ID, message timestamp, routing key and any subclass-specific envelope fields are not used for that write. The payload must still have a higher revision. The handled document's ID and collection remain unchanged; indexed start/end times retain the existing values unless the payload declares timestamp/end paths. A plain null result still deletes the document.

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

    • disabled

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