Question

first time post and new to google app engine!

i can’t for the life of me figure out why my attempts to access an object using Model.get_by_id does not function.

my test data is populated and i can verify the output as commented. i can confirm the ID of the data in the Datastore viewer… but attempts to use that ID fail to return the object.

    namespace_manager.set_namespace('myNamespace')

    for t in models.MyClass.all().fetch(100):
        print t.key().id() # prints the key and verified in the Datastore Viewer
        print t.date # prints the date

        myClassInstance = models.MyClass.get_by_id(t.key().id()) # never finds the object
        if tour is None:
            print "MyClass instance not found"

so output is

    6
    2012-04-24 20:47:13.537000
    MyClass instance not found
    27
    2012-04-24 20:47:13.605000
    MyClass instance not found
    29
    2012-04-24 20:47:13.611000
    MyClass instance not found
    31
    2012-04-24 20:47:13.617000
    MyClass instance not found

note that this is not a root entity and has children as well… but shouldn’t the MyClass.get_by_id method return the correct object?

thanks in advance!

Answer 1

if you are creating your entities with a parent/ancestor you need to provide that to the get_by_id function too.

entity = MyModel(parent = parentkey,
                 name   = 'somename')
entity.put()

entity_by_id = MyModel.get_by_id(entity.key().id(), parent = parentkey)