Add getitem support for QueryChain

sqlalchemy_utils/query_chain.py

@@ -44,5 +44,16 @@ class QueryChain(object):
             else:
                 skipped += obj_count
 
+    def __getitem__(self, key):
+        if isinstance(key, slice):
+            return self.__class__(
+                queries=self.queries,
+                limit=key.stop,
+                offset=key.start
+            )
+        else:
+            for obj in self[key:1]:
+                return obj
+
     def __repr__(self):
         return '<QueryChain at 0x%x>' % id(self)

tests/test_query_chain.py

@@ -80,3 +80,12 @@ class TestQueryChain(TestCase):
 
     def test_repr(self):
         assert repr(self.chain) == '<QueryChain at 0x%x>' % id(self.chain)
+
+    def test_getitem_with_slice(self):
+        chain = self.chain[1:]
+        assert chain.offset == 1
+        assert chain.limit is None
+
+    def test_getitem_with_single_key(self):
+        article = self.chain[2]
+        assert article == self.articles[0]