Empty result sets should not be fetched again

flask_sqlalchemy_cache/core.py

@@ -79,7 +79,7 @@ def get_value(self, merge=True, createfunc=None,
                                      ignore_expiration=ignore_expiration)
         else:
             cached_value = cache.get(cache_key)
-            if not cached_value:
+            if cached_value is None:
                 cached_value = createfunc()
                 cache.set(cache_key, cached_value, timeout=expiration_time)
 

flask_sqlalchemy_cache/tests/test_minimal.py

@@ -1,10 +1,12 @@
 # coding: UTF-8
 import unittest
+from unittest.mock import Mock, MagicMock
 
 from flask import Flask
-from flask.ext.sqlalchemy import SQLAlchemy, Model
-from flask.ext.cache import Cache
-from flask.ext.sqlalchemy_cache import CachingQuery, FromCache
+from flask_cache import Cache
+from flask_sqlalchemy import SQLAlchemy, Model
+from flask_sqlalchemy_cache import CachingQuery, FromCache
+
 
 Model.query_class = CachingQuery
 
@@ -69,6 +71,13 @@ def test_no_results(self):
         # regression test (check #3) to handle zero results gracefully
         Country.query.filter_by(name="URSS").options(FromCache(cache)).all()
 
+    def test_empty_results(self):
+        # An empty result set should not trigger another set
+        mock_cache = Mock()
+        mock_cache.get = MagicMock(return_value=[])
+        Country.query.filter_by(name="URSS").options(FromCache(mock_cache)).all()
+        mock_cache.set.assert_not_called()
+
     def test_special_chars(self):
         unicode_name = u"Côte d'Ivoire"
         unicode_country = Country(unicode_name)

setup.py

@@ -4,7 +4,7 @@
 
 setup(
     name='Flask-SQLAlchemy-Cache',
-    version='0.1.5',
+    version='0.1.6',
     description='CachingQuery implementation to Flask using Flask-SQLAlchemy and Flask-Cache',
     author='Iuri de Silvio',
     author_email='iurisilvio@gmail.com',
@@ -13,7 +13,7 @@
     platforms='any',
     packages=['flask_sqlalchemy_cache'],
     install_requires=[
-        'Flask>=0.9',
+        'Flask >=0.12, <1',
         'Flask-Cache',
         'Flask-SQLAlchemy',
     ],