better error messages for iterating on connection, database

pymongo/connection.py

@@ -228,3 +228,9 @@ class Connection(object):
         result = self[name]._command({"dropDatabase": 1})
         if result["ok"] != 1:
             raise OperationFailure("failed to drop database")
+
+    def __iter__(self):
+        return self
+
+    def next(self):
+        raise TypeError("'Connection' object is not iterable")

pymongo/database.py

@@ -237,3 +237,9 @@ class Database(object):
         """Returns a list containing current profiling information.
         """
         return list(self.system.profile.find())
+
+    def __iter__(self):
+        return self
+
+    def next(self):
+        raise TypeError("'Database' object is not iterable")

test/test_connection.py

@@ -101,5 +101,13 @@ class TestConnection(unittest.TestCase):
         dbs = connection.database_names()
         self.assertTrue("test" not in dbs)
 
+    def test_iteration(self):
+        connection = Connection(self.host, self.port)
+
+        def iterate():
+            [a for a in connection]
+
+        self.assertRaises(TypeError, iterate)
+
 if __name__ == "__main__":
     unittest.main()

test/test_database.py

@@ -155,6 +155,14 @@ class TestDatabase(unittest.TestCase):
         self.assertTrue(isinstance(info[0]["ts"], datetime.datetime))
         self.assertTrue(isinstance(info[0]["millis"], types.FloatType))
 
+    def test_iteration(self):
+        db = self.connection.test
+
+        def iterate():
+            [a for a in db]
+
+        self.assertRaises(TypeError, iterate)
+
     def test_save_find_one(self):
         db = Database(self.connection, "test")
         db.test.remove({})