Package com.google.appengine.tools.compilation

Class DatastoreCallbacksProcessor

  • All Implemented Interfaces:
    Processor
    @SupportedAnnotationTypes({"com.google.appengine.api.datastore.PrePut","com.google.appengine.api.datastore.PostPut","com.google.appengine.api.datastore.PreDelete","com.google.appengine.api.datastore.PostDelete","com.google.appengine.api.datastore.PreGet","com.google.appengine.api.datastore.PostLoad","com.google.appengine.api.datastore.PreQuery"})
@SupportedOptions("debug")
public class DatastoreCallbacksProcessor
extends AbstractProcessor
    Processes datastore callback annotations ( PrePut, PostPut, PreDelete, PostDelete, PreGet, PostLoad, PreQuery) and generates a config file that the Datastore API can load at runtime. Each line of the config file is of the format:
    kind.callback_type=comma-separated list of methods
    where 'kind' is the kind of the entity to which the config on that line applies, 'callback_type' is one of PrePut, PostPut, PreDelete, PostDelete, and each entry in the comma-separated list of methods is a colon-delimited fully-qualified classname:method name tuple. So for example, if the dev wants a method named 'prePutCallback1' belonging to class 'com.example.MyCallbacks and a method named 'prePutCallback2' belonging to the same class to be invoked before any entity of kind 'yar' is put, the config file will look like this: 
     yar.PrePut=com.example.MyCallbacks:prePutCallback1,com.example.MyCallbacks:prePutCallback2
    Note that it is possible to have a line which refers to all kinds by omitting the kind name: 
     .PreDelete=com.example.MyCallbacks:preDeleteCallback1

    Each type of callback has its own signature requirements for the methods it annotates. If any of these signature requirements are violated the processor will produce an error. See the javadoc for the annotations for more information about the callback-specific signature requirements.

    Processor Options:

    • debug - turns on debug statements