Allow to loads undeclared field with meta attribute (fix #934)

docs/apireference.rst

@@ -34,6 +34,9 @@ Documents
 .. autoclass:: mongoengine.ValidationError
   :members:
 
+.. autoclass:: mongoengine.FieldDoesNotExist
+
+
 Context Managers
 ================
 

mongoengine/base/document.py

@@ -70,9 +70,9 @@ def __init__(self, *args, **values):
 
         signals.pre_init.send(self.__class__, document=self, values=values)
 
-        # Check if there are undefined fields supplied, if so raise an
-        # Exception.
-        if not self._dynamic:
+        # Check if there are undefined fields supplied to the constructor,
+        # if so raise an Exception.
+        if not self._dynamic and (self._meta.get('strict', True) or _created):
             for var in values.keys():
                 if var not in self._fields.keys() + ['id', 'pk', '_cls', '_text_score']:
                     msg = (

mongoengine/document.py

@@ -135,6 +135,11 @@ class Document(BaseDocument):
     doesn't contain a list) if allow_inheritance is True. This can be
     disabled by either setting cls to False on the specific index or
     by setting index_cls to False on the meta dictionary for the document.
+
+    By default, any extra attribute existing in stored data but not declared
+    in your model will raise a :class:`~mongoengine.FieldDoesNotExist` error.
+    This can be disabled by setting :attr:`strict` to ``False``
+    in the :attr:`meta` dictionnary.
     """
 
     # The __metaclass__ attribute is removed by 2to3 when running with Python3

mongoengine/errors.py

@@ -42,7 +42,14 @@ class NotUniqueError(OperationError):
 
 
 class FieldDoesNotExist(Exception):
-    pass
+    """Raised when trying to set a field
+    not declared in a :class:`~mongoengine.Document`
+    or an :class:`~mongoengine.EmbeddedDocument`.
+
+    To avoid this behavior on data loading,
+    you should the :attr:`strict` to ``False``
+    in the :attr:`meta` dictionnary.
+    """
 
 
 class ValidationError(AssertionError):

tests/document/instance.py

@@ -16,7 +16,8 @@
 
 from mongoengine import *
 from mongoengine.errors import (NotRegistered, InvalidDocumentError,
-                                InvalidQueryError, NotUniqueError)
+                                InvalidQueryError, NotUniqueError,
+                                FieldDoesNotExist)
 from mongoengine.queryset import NULLIFY, Q
 from mongoengine.connection import get_db
 from mongoengine.base import get_document
@@ -2467,6 +2468,114 @@ class Group(Document):
         group = Group.objects.first()
         self.assertEqual("hello - default", group.name)
 
+    def test_load_undefined_fields(self):
+        class User(Document):
+            name = StringField()
+
+        User.drop_collection()
+
+        User._get_collection().save({
+            'name': 'John',
+            'foo': 'Bar',
+            'data': [1, 2, 3]
+        })
+
+        self.assertRaises(FieldDoesNotExist, User.objects.first)
+
+    def test_load_undefined_fields_with_strict_false(self):
+        class User(Document):
+            name = StringField()
+
+            meta = {'strict': False}
+
+        User.drop_collection()
+
+        User._get_collection().save({
+            'name': 'John',
+            'foo': 'Bar',
+            'data': [1, 2, 3]
+        })
+
+        user = User.objects.first()
+        self.assertEqual(user.name, 'John')
+        self.assertFalse(hasattr(user, 'foo'))
+        self.assertEqual(user._data['foo'], 'Bar')
+        self.assertFalse(hasattr(user, 'data'))
+        self.assertEqual(user._data['data'], [1, 2, 3])
+
+    def test_load_undefined_fields_on_embedded_document(self):
+        class Thing(EmbeddedDocument):
+            name = StringField()
+
+        class User(Document):
+            name = StringField()
+            thing = EmbeddedDocumentField(Thing)
+
+        User.drop_collection()
+
+        User._get_collection().save({
+            'name': 'John',
+            'thing': {
+                'name': 'My thing',
+                'foo': 'Bar',
+                'data': [1, 2, 3]
+            }
+        })
+
+        self.assertRaises(FieldDoesNotExist, User.objects.first)
+
+    def test_load_undefined_fields_on_embedded_document_with_strict_false_on_doc(self):
+        class Thing(EmbeddedDocument):
+            name = StringField()
+
+        class User(Document):
+            name = StringField()
+            thing = EmbeddedDocumentField(Thing)
+
+            meta = {'strict': False}
+
+        User.drop_collection()
+
+        User._get_collection().save({
+            'name': 'John',
+            'thing': {
+                'name': 'My thing',
+                'foo': 'Bar',
+                'data': [1, 2, 3]
+            }
+        })
+
+        self.assertRaises(FieldDoesNotExist, User.objects.first)
+
+    def test_load_undefined_fields_on_embedded_document_with_strict_false(self):
+        class Thing(EmbeddedDocument):
+            name = StringField()
+
+            meta = {'strict': False}
+
+        class User(Document):
+            name = StringField()
+            thing = EmbeddedDocumentField(Thing)
+
+        User.drop_collection()
+
+        User._get_collection().save({
+            'name': 'John',
+            'thing': {
+                'name': 'My thing',
+                'foo': 'Bar',
+                'data': [1, 2, 3]
+            }
+        })
+
+        user = User.objects.first()
+        self.assertEqual(user.name, 'John')
+        self.assertEqual(user.thing.name, 'My thing')
+        self.assertFalse(hasattr(user.thing, 'foo'))
+        self.assertEqual(user.thing._data['foo'], 'Bar')
+        self.assertFalse(hasattr(user.thing, 'data'))
+        self.assertEqual(user.thing._data['data'], [1, 2, 3])
+
     def test_spaces_in_keys(self):
 
         class Embedded(DynamicEmbeddedDocument):

tests/fields/fields.py

@@ -3160,7 +3160,7 @@ class Doc(Document):
 
     def test_undefined_field_exception(self):
         """Tests if a `FieldDoesNotExist` exception is raised when trying to
-        set a value to a field that's not defined.
+        instanciate a document with a field that's not defined.
         """
 
         class Doc(Document):
@@ -3171,6 +3171,21 @@ def test():
 
         self.assertRaises(FieldDoesNotExist, test)
 
+    def test_undefined_field_exception_with_strict(self):
+        """Tests if a `FieldDoesNotExist` exception is raised when trying to
+        instanciate a document with a field that's not defined,
+        even when strict is set to False.
+        """
+
+        class Doc(Document):
+            foo = StringField(db_field='f')
+            meta = {'strict': False}
+
+        def test():
+            Doc(bar='test')
+
+        self.assertRaises(FieldDoesNotExist, test)
+
 
 class EmbeddedDocumentListFieldTestCase(unittest.TestCase):