Replace ReferenceError with umongo NoneReferenceError

umongo/__init__.py

@@ -22,6 +22,7 @@
     DeleteError,
     NotCreatedError,
     FieldNotLoadedError,
+    NoneReferenceError,
     UnknownFieldInDBError,
 )
 from . import fields, validate
@@ -58,6 +59,7 @@
     'DeleteError',
     'NotCreatedError',
     'FieldNotLoadedError',
+    'NoneReferenceError',
     'UnknownFieldInDBError',
 
     'fields',

umongo/exceptions.py

@@ -46,5 +46,9 @@ class FieldNotLoadedError(UMongoError):
     """Accessing a field not loaded after partial load"""
 
 
+class NoneReferenceError(UMongoError):
+    """Retrieving a None reference"""
+
+
 class UnknownFieldInDBError(UMongoError):
     """Data from database contains unknown field"""

umongo/frameworks/motor_asyncio.py

@@ -9,7 +9,9 @@
 from ..document import DocumentImplementation
 from ..data_proxy import missing
 from ..data_objects import Reference
-from ..exceptions import NotCreatedError, UpdateError, ValidationError, DeleteError
+from ..exceptions import (
+    NotCreatedError, UpdateError, DeleteError, ValidationError, NoneReferenceError
+)
 from ..fields import ReferenceField, ListField, EmbeddedField
 from ..query_mapper import map_query
 
@@ -356,7 +358,7 @@ def __init__(self, *args, **kwargs):
     async def fetch(self, no_data=False, force_reload=False):
         if not self._document or force_reload:
             if self.pk is None:
-                raise ReferenceError('Cannot retrieve a None Reference')
+                raise NoneReferenceError('Cannot retrieve a None Reference')
             self._document = await self.document_cls.find_one(self.pk)
             if not self._document:
                 raise ValidationError(self.error_messages['not_found'].format(

umongo/frameworks/pymongo.py

@@ -6,7 +6,9 @@
 from ..document import DocumentImplementation
 from ..data_proxy import missing
 from ..data_objects import Reference
-from ..exceptions import NotCreatedError, UpdateError, DeleteError, ValidationError
+from ..exceptions import (
+    NotCreatedError, UpdateError, DeleteError, ValidationError, NoneReferenceError
+)
 from ..fields import ReferenceField, ListField, EmbeddedField
 from ..query_mapper import map_query
 
@@ -291,7 +293,7 @@ def __init__(self, *args, **kwargs):
     def fetch(self, no_data=False, force_reload=False):
         if not self._document or force_reload:
             if self.pk is None:
-                raise ReferenceError('Cannot retrieve a None Reference')
+                raise NoneReferenceError('Cannot retrieve a None Reference')
             self._document = self.document_cls.find_one(self.pk)
             if not self._document:
                 raise ValidationError(self.error_messages['not_found'].format(

umongo/frameworks/txmongo.py

@@ -8,7 +8,9 @@
 from ..document import DocumentImplementation
 from ..data_proxy import missing
 from ..data_objects import Reference
-from ..exceptions import NotCreatedError, UpdateError, DeleteError, ValidationError
+from ..exceptions import (
+    NotCreatedError, UpdateError, DeleteError, ValidationError, NoneReferenceError
+)
 from ..fields import ReferenceField, ListField, EmbeddedField
 from ..query_mapper import map_query
 
@@ -297,7 +299,7 @@ def __init__(self, *args, **kwargs):
     def fetch(self, no_data=False, force_reload=False):
         if not self._document or force_reload:
             if self.pk is None:
-                raise ReferenceError('Cannot retrieve a None Reference')
+                raise NoneReferenceError('Cannot retrieve a None Reference')
             self._document = yield self.document_cls.find_one(self.pk)
             if not self._document:
                 raise ValidationError(self.error_messages['not_found'].format(