The HibernateSaveProcessor ( implements SaveProcessor)

The HibernateSaveProcessor class is responsible for taking a JSON payload from the Breeze client, and saving it through Hibernate. Under the hood several steps occur in this process.

1. Converting from JSON to Java entities
2. Re-establishing the relationships between entities, based on the foreign keys
3. Calling SaveWorkState.beforeSaveEntities to allow pre-save processing
4. Associating the entities to a Hibernate Session
5. Calling SaveWorkState.beforeCommit to allow additional pre-save processing
6. Saving the entities in the session to the database
7. Keeping track of the mapping between temporary (client-generated) keys and real (server-generated) keys.
8. Removing the relationships between entities, so they can be returned to the Breeze client.
9. Calling SaveWorkState.afterSaveEntities to allow post-save processing
10. Converting the entities and key mappings to a SaveResult
11. Converting the SaveResult to JSON
12. Handling errors

Errors from the database or in other processing are returned as an HTTP 500 response. Data validation errors or other application-supplied EntityErrors are returned as an HTTP 403 (Forbidden) response.

Example

The HibernateSaveProcessor is used to implement any endpoint to a breezejs SaveChanges call. In the example below, we are assuming that the Java servlet method has been called as a result of a BreezeJS saveChanges call.

public void saveChanges(HttpServletRequest request, HttpServletResponse response) {
    // extractSaveBundle is a method in the breeze-webservice lib
    // that will be described later.
    Map saveBundle = extractSaveBundle(request);
    SaveWorkState sws = new SaveWorkState(saveBundle);
    SaveProcessor processor = new HibernateSaveProcessor(metadata, sessionFactory);
    SaveResult sr = processor.saveChanges(saveWorkState);

    writeSaveResponse(response, sr);
}

The SaveWorkState object mentioned above is a wrapper over the save data that is passed in from the client saveChanges call. In addition, the SaveWorkState may be subclassed to add custom handling to the save process. The SaveWorkState has a beforeSaveEntity, beforeSaveEntities and a beforeCommit method that will all be called during save processing. These are discussed in more detail in the breeze-webserver section.