Fix long fields stored as int32 in Python 3. issue #1253

AUTHORS

@@ -235,3 +235,4 @@ that much better:
  * Steven Rossiter (https://github.com/BeardedSteve)
  * Luo Peng (https://github.com/RussellLuo)
  * Bryan Bennett (https://github.com/bbenne10)
+ * Gilb's Gilb's (https://github.com/gilbsgilbs)

mongoengine/fields.py

@@ -19,7 +19,7 @@ else:
 
 import pymongo
 import gridfs
-from bson import Binary, DBRef, SON, ObjectId
+from bson import Binary, DBRef, SON, ObjectId, Int64
 
 from mongoengine.errors import ValidationError
 from mongoengine.python_support import (PY3, bin_type, txt_type,
@@ -227,6 +227,9 @@ class LongField(BaseField):
             pass
         return value
 
+    def to_mongo(self, value, **kwargs):
+        return Int64(value)
+
     def validate(self, value):
         try:
             value = long(value)

tests/fields/fields.py

@@ -21,6 +21,7 @@ except ImportError:
 from decimal import Decimal
 
 from bson import Binary, DBRef, ObjectId
+from bson.int64 import Int64
 
 from mongoengine import *
 from mongoengine.connection import get_db
@@ -4114,6 +4115,19 @@ class EmbeddedDocumentListFieldTestCase(unittest.TestCase):
         self.assertTrue(hasattr(CustomData.c_field, 'custom_data'))
         self.assertEqual(custom_data['a'], CustomData.c_field.custom_data['a'])
 
+    def test_long_field_is_stored_as_long(self):
+        """
+        Tests that long fields are stored as long in mongo, even if long value
+        is small enough to be an int.
+        """
+        class TestDocument(Document):
+            some_long = LongField()
+
+        doc = TestDocument(some_long=42).save()
+        db = get_db()
+        self.assertTrue(isinstance(get_db().test_document.find()[0]['some_long'], Int64))
+        self.assertTrue(isinstance(doc.some_long, (int, long,)))
+
 
 if __name__ == '__main__':
     unittest.main()