From 9f4b04ea0f4d4a6d15a3f59f674d11f073ebe2a1 Mon Sep 17 00:00:00 2001
From: Manuel Jeckelmann <maennel@users.noreply.github.com>
Date: Thu, 22 Dec 2016 19:19:18 +0100
Subject: [PATCH] Fix querying an embedded document field by an invalid value
 (#1440)

---
 mongoengine/base/document.py |  6 ++++--
 mongoengine/fields.py        |  8 ++++++--
 tests/document/instance.py   |  4 ++++
 tests/queryset/queryset.py   | 18 ++++++++++++++++--
 4 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/mongoengine/base/document.py b/mongoengine/base/document.py
index 03dc7562..03536d6f 100644
--- a/mongoengine/base/document.py
+++ b/mongoengine/base/document.py
@@ -16,8 +16,7 @@ from mongoengine.base.datastructures import (BaseDict, BaseList,
                                              SemiStrictDict, StrictDict)
 from mongoengine.base.fields import ComplexBaseField
 from mongoengine.common import _import_class
-from mongoengine.errors import (FieldDoesNotExist, InvalidDocumentError,
-                                LookUpError, OperationError, ValidationError)
+from mongoengine.errors import (FieldDoesNotExist, InvalidDocumentError, LookUpError, OperationError, ValidationError)
 
 __all__ = ('BaseDocument',)
 
@@ -675,6 +674,9 @@ class BaseDocument(object):
         if not only_fields:
             only_fields = []
 
+        if son and not isinstance(son, dict):
+            raise ValueError("The source SON object needs to be of type 'dict'")
+
         # Get the class name from the document, falling back to the given
         # class if unavailable
         class_name = son.get('_cls', cls._class_name)
diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index d812a762..3991ef5c 100644
--- a/mongoengine/fields.py
+++ b/mongoengine/fields.py
@@ -28,7 +28,7 @@ from mongoengine.base import (BaseDocument, BaseField, ComplexBaseField,
                               GeoJsonBaseField, ObjectIdField, get_document)
 from mongoengine.connection import DEFAULT_CONNECTION_NAME, get_db
 from mongoengine.document import Document, EmbeddedDocument
-from mongoengine.errors import DoesNotExist, ValidationError
+from mongoengine.errors import DoesNotExist, InvalidQueryError, ValidationError
 from mongoengine.python_support import StringIO
 from mongoengine.queryset import DO_NOTHING, QuerySet
 
@@ -566,7 +566,11 @@ class EmbeddedDocumentField(BaseField):
 
     def prepare_query_value(self, op, value):
         if value is not None and not isinstance(value, self.document_type):
-            value = self.document_type._from_son(value)
+            try:
+                value = self.document_type._from_son(value)
+            except ValueError:
+                raise InvalidQueryError("Querying the embedded document '%s' failed, due to an invalid query value" %
+                                        (self.document_type._class_name,))
         super(EmbeddedDocumentField, self).prepare_query_value(op, value)
         return self.to_mongo(value)
 
diff --git a/tests/document/instance.py b/tests/document/instance.py
index b92bafa9..d961f034 100644
--- a/tests/document/instance.py
+++ b/tests/document/instance.py
@@ -1860,6 +1860,10 @@ class InstanceTest(unittest.TestCase):
                 'occurs': {"hello": None}
             })
 
+        # Tests for issue #1438: https://github.com/MongoEngine/mongoengine/issues/1438
+        with self.assertRaises(ValueError):
+            Word._from_son('this is not a valid SON dict')
+
     def test_reverse_delete_rule_cascade_and_nullify(self):
         """Ensure that a referenced document is also deleted upon deletion.
         """
diff --git a/tests/queryset/queryset.py b/tests/queryset/queryset.py
index 11ce0a27..a15807a5 100644
--- a/tests/queryset/queryset.py
+++ b/tests/queryset/queryset.py
@@ -1266,7 +1266,7 @@ class QuerySetTest(unittest.TestCase):
 
     def test_find_embedded(self):
         """Ensure that an embedded document is properly returned from
-        a query.
+        different manners of querying.
         """
         class User(EmbeddedDocument):
             name = StringField()
@@ -1277,8 +1277,9 @@ class QuerySetTest(unittest.TestCase):
 
         BlogPost.drop_collection()
 
+        user = User(name='Test User')
         BlogPost.objects.create(
-            author=User(name='Test User'),
+            author=user,
             content='Had a good coffee today...'
         )
 
@@ -1286,6 +1287,19 @@ class QuerySetTest(unittest.TestCase):
         self.assertTrue(isinstance(result.author, User))
         self.assertEqual(result.author.name, 'Test User')
 
+        result = BlogPost.objects.get(author__name=user.name)
+        self.assertTrue(isinstance(result.author, User))
+        self.assertEqual(result.author.name, 'Test User')
+
+        result = BlogPost.objects.get(author={'name': user.name})
+        self.assertTrue(isinstance(result.author, User))
+        self.assertEqual(result.author.name, 'Test User')
+
+        # Fails, since the string is not a type that is able to represent the
+        # author's document structure (should be dict)
+        with self.assertRaises(InvalidQueryError):
+            BlogPost.objects.get(author=user.name)
+
     def test_find_empty_embedded(self):
         """Ensure that you can save and find an empty embedded document."""
         class User(EmbeddedDocument):