Simple implementation of BinaryField

mongoengine/fields.py

@@ -11,7 +11,8 @@ import decimal
 __all__ = ['StringField', 'IntField', 'FloatField', 'BooleanField',
            'DateTimeField', 'EmbeddedDocumentField', 'ListField', 'DictField',
            'ObjectIdField', 'ReferenceField', 'ValidationError',
-           'DecimalField', 'URLField', 'GenericReferenceField']
+           'DecimalField', 'URLField', 'GenericReferenceField',
+           'BinaryField']
 
 RECURSIVE_REFERENCE_CONSTANT = 'self'
 
@@ -442,3 +443,16 @@ class GenericReferenceField(BaseField):
 
     def prepare_query_value(self, op, value):
         return self.to_mongo(value)['_ref']
+
+class BinaryField(BaseField):
+    """A binary data field.
+    """
+
+    def __init__(self, **kwargs):
+        super(BinaryField, self).__init__(**kwargs)
+
+    def to_mongo(self, value):
+        return pymongo.binary.Binary(value)
+
+    def to_python(self, value):
+        return str(value)

tests/fields.py

@@ -495,6 +495,24 @@ class FieldTest(unittest.TestCase):
         Post.drop_collection()
         User.drop_collection()
 
+    def test_binary_fields(self):
+        """Ensure that binary fields can be stored and retrieved.
+        """
+        class Attachment(Document):
+            content_type = StringField()
+            blob = BinaryField()
+
+        BLOB = '\xe6\x00\xc4\xff\x07'
+        MIME_TYPE = 'application/octet-stream'
+
+        Attachment.drop_collection()
+
+        attachment = Attachment(content_type=MIME_TYPE, blob=BLOB)
+        attachment.save()
+
+        attachment_1 = Attachment.objects().first()
+        self.assertEqual(MIME_TYPE, attachment_1.content_type)
+        self.assertEqual(BLOB, attachment_1.blob)
 
 if __name__ == '__main__':
     unittest.main()