Add support for prefetching fields
This makes it possible to specify the fields that should be
prefetched as part of a getForFields query. Doing a prefetch on a
ReferenceProperty when it is known that the property will be
referenced in (almost all) entities is far more efficient than
doing the invididual fetches sequentially.
"Global Django exceptions"
class ObjectDoesNotExist(Exception):
"The requested object does not exist"
silent_variable_failure = True
class MultipleObjectsReturned(Exception):
"The query returned multiple objects when only one was expected."
pass
class SuspiciousOperation(Exception):
"The user did something suspicious"
pass
class PermissionDenied(Exception):
"The user did not have permission to do that"
pass
class ViewDoesNotExist(Exception):
"The requested view does not exist"
pass
class MiddlewareNotUsed(Exception):
"This middleware is not used in this server configuration"
pass
class ImproperlyConfigured(Exception):
"Django is somehow improperly configured"
pass
class FieldError(Exception):
"""Some kind of problem with a model field."""
pass
class ValidationError(Exception):
"""An error while validating data."""
pass