Fixed Query.exists() method for the case, when query doesn't have any filters applied.pr/24

2 files changed, 11 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index b71bfe08f..d64575aec 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -2494,7 +2494,7 @@ class Query(object):
         .. versionadded:: 0.8.1
 
         """
-        return sql.exists(self.with_entities('1').statement)
+        return sql.exists(self.statement.with_only_columns(['1']))
 
     def count(self):
         """Return a count of rows this Query would return.
diff --git a/test/orm/test_query.py b/test/orm/test_query.py
index 0973dc357..7151ef0b6 100644
--- a/test/orm/test_query.py
+++ b/test/orm/test_query.py
@@ -1730,9 +1730,18 @@ class ExistsTest(QueryTest, AssertsCompiledSQL):
     def test_exists(self):
         User = self.classes.User
         sess = create_session()
-        q1 = sess.query(User).filter(User.name == 'fred')
+
+        q1 = sess.query(User)
         self.assert_compile(sess.query(q1.exists()),
             'SELECT EXISTS ('
+                'SELECT 1 FROM users'
+            ') AS anon_1',
+            dialect=default.DefaultDialect()
+        )
+
+        q2 = sess.query(User).filter(User.name == 'fred')
+        self.assert_compile(sess.query(q2.exists()),
+            'SELECT EXISTS ('
                 'SELECT 1 FROM users WHERE users.name = :name_1'
             ') AS anon_1',
             dialect=default.DefaultDialect()