More efficient contains method for proxy dict

CHANGES.rst

@@ -4,6 +4,12 @@ Changelog
 Here you can see the full list of changes between each SQLAlchemy-Utils release.
 
 
+0.12.5 (2013-06-05)
+^^^^^^^^^^^^^^^^^^^
+
+- ProxyDict now contains None values in cache - more efficient contains method.
+
+
 0.12.4 (2013-06-01)
 ^^^^^^^^^^^^^^^^^^^
 

setup.py

@@ -24,7 +24,7 @@ class PyTest(Command):
 
 setup(
     name='SQLAlchemy-Utils',
-    version='0.12.4',
+    version='0.12.5',
     url='https://github.com/kvesteri/sqlalchemy-utils',
     license='BSD',
     author='Konsta Vesterinen',

sqlalchemy_utils/proxy_dict.py

@@ -18,10 +18,9 @@ class ProxyDict(object):
         return [x[0] for x in self.collection.values(descriptor)]
 
     def __contains__(self, key):
-        try:
-            return key in self.cache or self.fetch(key) is not None
-        except KeyError:
-            return False
+        if key in self.cache:
+            return self.cache[key] is not None
+        return self.fetch(key) is not None
 
     def has_key(self, key):
         return self.__contains__(key)
@@ -29,7 +28,9 @@ class ProxyDict(object):
     def fetch(self, key):
         session = sa.orm.object_session(self.parent)
         if session and sa.orm.util.has_identity(self.parent):
-            return self.collection.filter_by(**{self.key_name: key}).first()
+            obj = self.collection.filter_by(**{self.key_name: key}).first()
+            self.cache[key] = obj
+            return obj
 
     def create_new_instance(self, key):
         value = self.child_class(**{self.key_name: key})
@@ -39,11 +40,12 @@ class ProxyDict(object):
 
     def __getitem__(self, key):
         if key in self.cache:
-            return self.cache[key]
-
-        value = self.fetch(key)
-        if value:
-            return value
+            if self.cache[key] is not None:
+                return self.cache[key]
+        else:
+            value = self.fetch(key)
+            if value:
+                return value
 
         return self.create_new_instance(key)
 

tests/__init__.py

@@ -5,31 +5,37 @@ from sqlalchemy.orm import sessionmaker
 from sqlalchemy.ext.declarative import declarative_base
 
 from sqlalchemy_utils import (
-    escape_like,
-    sort_query,
     InstrumentedList,
-    PhoneNumber,
     PhoneNumberType,
-    merge
 )
 
 
+@sa.event.listens_for(sa.engine.Engine, 'before_cursor_execute')
+def count_sql_calls(conn, cursor, statement, parameters, context, executemany):
+    try:
+        conn.query_count += 1
+    except AttributeError:
+        conn.query_count = 0
+
+
 class TestCase(object):
     def setup_method(self, method):
         self.engine = create_engine(
             'postgres://postgres@localhost/sqlalchemy_utils_test'
         )
+        self.connection = self.engine.connect()
         self.Base = declarative_base()
 
         self.create_models()
-        self.Base.metadata.create_all(self.engine)
+        self.Base.metadata.create_all(self.connection)
 
-        Session = sessionmaker(bind=self.engine)
+        Session = sessionmaker(bind=self.connection)
         self.session = Session()
 
     def teardown_method(self, method):
         self.session.close_all()
-        self.Base.metadata.drop_all(self.engine)
+        self.Base.metadata.drop_all(self.connection)
+        self.connection.close()
         self.engine.dispose()
 
     def create_models(self):

tests/test_proxy_dict.py

@@ -79,6 +79,25 @@ class TestProxyDict(TestCase):
         )
         article.translations['en']
 
+    def test_contains_efficiency(self):
+        article = self.Article()
+        self.session.add(article)
+        self.session.commit()
+        article.id
+        query_count = self.connection.query_count
+        'en' in article.translations
+        'en' in article.translations
+        'en' in article.translations
+        assert self.connection.query_count == query_count + 1
+
+    def test_getitem_with_none_value_in_cache(self):
+        article = self.Article()
+        self.session.add(article)
+        self.session.commit()
+        article.id
+        'en' in article.translations
+        assert article.translations['en']
+
     def test_contains(self):
         article = self.Article()
         assert 'en' not in article.translations