Add count() support to find_streams

Returns [{'count': num_streams}]

Change-Id: I37e7fc462a14dda793ac5c231439ed7d5e5ee523

tests/test_db.py

@@ -446,4 +446,6 @@ class TestDB(unittest.TestCase):
         with self.assertRaises(db.NoSuchStreamError):
             self.db.get_stream_by_id(1)
 
-
+    def test_find_stream_count(self):
+        count = self.db.find_streams(count=True)
+        self.assertEqual([{'count': 8}], count)

winchester/db/interface.py

@@ -235,7 +235,8 @@ class DBInterface(object):
         return stream
 
     @sessioned
-    def find_streams(self, stream_id=None, state=None, older_than=None, younger_than=None,
+    def find_streams(self, count=False, stream_id=None, state=None,
+                     older_than=None, younger_than=None,
                      name=None, distinguishing_traits=None,
                      session=None, include_events=False):
         q = session.query(models.Stream)
@@ -254,6 +255,11 @@ class DBInterface(object):
                 q = q.filter(models.Stream.distinguished_by.any(and_(
                         models.DistinguishingTrait.name == name,
                         models.DistinguishingTrait.value == val)))
+
+        if count:
+            q = q.count()
+            return [{"count": q}]
+
         stream_info = []
         for stream in q.all():
             info = stream.as_dict