Fixes read_preference

Fixes mongoengine/mongoengine#10

docs/changelog.rst

@@ -4,6 +4,7 @@ Changelog
 
 Changes in 0.6.X
 ================
+- Bug fix Read preference now passed correctly
 - Added support for File like objects for GridFS
 - Fix for #473 - Dereferencing abstracts
 

mongoengine/connection.py

@@ -63,7 +63,8 @@ def register_connection(alias, name, host='localhost', port=27017,
             'password': uri_dict.get('password'),
             'read_preference': read_preference,
         })
-
+        if "replicaSet" in host:
+            conn_settings['replicaSet'] = True
     _connection_settings[alias] = conn_settings
 
 
@@ -112,7 +113,11 @@ def get_connection(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
             conn_settings['hosts_or_uri'] = conn_settings.pop('host', None)
             # Discard port since it can't be used on ReplicaSetConnection
             conn_settings.pop('port', None)
+            # Discard replicaSet if not base string
+            if not isinstance(conn_settings['replicaSet'], basestring):
+                conn_settings.pop('replicaSet', None)
             connection_class = ReplicaSetConnection
+
         try:
             _connections[alias] = connection_class(**conn_settings)
         except Exception, e:

tests/replicaset_connection.py

@@ -0,0 +1,28 @@
+import unittest
+import pymongo
+from pymongo import ReadPreference
+
+import mongoengine
+from mongoengine import *
+from mongoengine.connection import get_db, get_connection, ConnectionError
+
+
+class ConnectionTest(unittest.TestCase):
+
+    def tearDown(self):
+        mongoengine.connection._connection_settings = {}
+        mongoengine.connection._connections = {}
+        mongoengine.connection._dbs = {}
+
+    def test_replicaset_uri_passes_read_preference(self):
+        """Requires a replica set called "rs" on port 27017
+        """
+        try:
+            conn = connect(db='mongoenginetest', host="mongodb://localhost/mongoenginetest?replicaSet=rs", read_preference=ReadPreference.SECONDARY_ONLY)
+        except ConnectionError, e:
+            return
+
+        self.assertEquals(conn.read_preference, ReadPreference.SECONDARY_ONLY)
+
+if __name__ == '__main__':
+    unittest.main()