Fix for get_top query in MySQL; all tests now pass in MySQL

git-svn-id: https://django-voting.googlecode.com/svn/trunk@54 662f01ad-f42a-0410-a340-718c64ddaef4

managers.py

@@ -1,3 +1,4 @@
+from django.conf import settings
 from django.db import backend, connection, models
 from django.contrib.contenttypes.models import ContentType
 
@@ -16,7 +17,9 @@ def get_score(self, obj):
         cursor = connection.cursor()
         cursor.execute(query, [ctype.id, obj._get_pk_val()])
         result = cursor.fetchall()[0]
-        return {'score': result[0] or 0, 'num_votes': result[1]}
+        # MySQL returns floats and longs respectively for these
+        # results, so we need to convert them to ints explicitly.
+        return {'score': result[0] and int(result[0]) or 0, 'num_votes': int(result[1])}
 
     def get_scores_in_bulk(self, objects):
         """
@@ -36,9 +39,9 @@ def get_scores_in_bulk(self, objects):
         cursor = connection.cursor()
         cursor.execute(query, [ctype.id] + [obj._get_pk_val() for obj in objects])
         results = cursor.fetchall()
-        return dict([(object_id, {
-                          'score': score,
-                          'num_votes': num_votes,
+        return dict([(int(object_id), {
+                          'score': int(score),
+                          'num_votes': int(num_votes),
                       }) for object_id, score, num_votes in results])
 
     def record_vote(self, obj, user, vote):
@@ -71,14 +74,27 @@ def get_top(self, Model, limit=10, reversed=False):
         """
         ctype = ContentType.objects.get_for_model(Model)
         query = """
-        SELECT object_id, SUM(vote)
+        SELECT object_id, SUM(vote) as %s
         FROM %s
         WHERE content_type_id = %%s
-        GROUP BY object_id""" % backend.quote_name(self.model._meta.db_table)
+        GROUP BY object_id""" % (
+            backend.quote_name('score'),
+            backend.quote_name(self.model._meta.db_table),
+        )
+
+        # MySQL has issues with re-using the aggregate function in the
+        # HAVING clause, so we alias the score and use this alias for
+        # its benefit.
+        if settings.DATABASE_ENGINE == 'mysql':
+            having_score = backend.quote_name('score')
+        else:
+            having_score = 'SUM(vote)'
         if reversed:
-            query += ' HAVING SUM(vote) < 0 ORDER BY SUM(vote) ASC LIMIT %s'
+            having_sql = ' HAVING %(having_score)s < 0 ORDER BY %(having_score)s ASC LIMIT %%s'
         else:
-            query += ' HAVING SUM(vote) > 0 ORDER BY SUM(vote) DESC LIMIT %s'
+            having_sql = ' HAVING %(having_score)s > 0 ORDER BY %(having_score)s DESC LIMIT %%s'
+        query += having_sql % {'having_score': having_score}
+
         cursor = connection.cursor()
         cursor.execute(query, [ctype.id, limit])
         results = cursor.fetchall()
@@ -90,7 +106,7 @@ def get_top(self, Model, limit=10, reversed=False):
         # relations, missing objects are silently ignored.
         for id, score in results:
             if id in objects:
-                yield objects[id], score
+                yield objects[id], int(score)
 
     def get_bottom(self, Model, limit=10):
         """

tests/settings.py

@@ -5,10 +5,20 @@
 
 DATABASE_ENGINE = 'sqlite3'
 DATABASE_NAME = os.path.join(DIRNAME, 'database.db')
-DATABASE_USER = ''
-DATABASE_PASSWORD = ''
-DATABASE_HOST = ''
-DATABASE_PORT = ''
+
+#DATABASE_ENGINE = 'mysql'
+#DATABASE_NAME = 'tagging_test'
+#DATABASE_USER = 'root'
+#DATABASE_PASSWORD = ''
+#DATABASE_HOST = 'localhost'
+#DATABASE_PORT = '3306'
+
+#DATABASE_ENGINE = 'postgresql_psycopg2'
+#DATABASE_NAME = 'tagging_test'
+#DATABASE_USER = 'postgres'
+#DATABASE_PASSWORD = ''
+#DATABASE_HOST = 'localhost'
+#DATABASE_PORT = '5432'
 
 INSTALLED_APPS = (
     'django.contrib.auth',

tests/tests.py

@@ -80,4 +80,6 @@
 >>> list(Vote.objects.get_bottom(Item))
 [(<Item: test3>, -4), (<Item: test4>, -3), (<Item: test2>, -2)]
 
+>>> Vote.objects.get_scores_in_bulk([i1, i2, i3, i4])
+{1: {'score': 0, 'num_votes': 4}, 2: {'score': -2, 'num_votes': 4}, 3: {'score': -4, 'num_votes': 4}, 4: {'score': -3, 'num_votes': 3}}
 """