Replace BooleanSum with Django native stuff

We now no longer need to guess database backend.

Fixes #946
Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/boolean_sum.py

@@ -23,56 +23,16 @@ Wrapper for Sum to work with PostgreSQL database.
 See also https://code.djangoproject.com/ticket/17564
 '''
 from django.conf import settings
-from django.db.models.aggregates import Sum
-from django.db.models.sql.aggregates import Sum as BaseSQLSum
+from django.db.models import Sum, When, Case, IntegerField
 
 
-def get_template():
-    '''
-    Adds type casting to boolean values for PostgreSQL.
-    '''
-    engine = settings.DATABASES['default']['ENGINE']
-    if 'psycopg2' in engine or 'postgres' in engine:
-        return '%(function)s(%(field)s::int)'
-    return '%(function)s(%(field)s)'
-
-
-class SQLSum(BaseSQLSum):
-    @property
-    def sql_template(self):
-        """
-        Returns template for the SQL
-        """
-        return get_template()
-
-
-class BooleanSum(Sum):
-    '''
-    Sum for boolean fields.
-    '''
-    # pylint: disable=W0223
-    def add_to_query(self, query, alias, col, source, is_summary):
-        '''
-        Generates query to use SQLSum class with type casting.
-
-        Used for Django 1.7
-        '''
-        aggregate = SQLSum(
-            col, source=source, is_summary=is_summary, **self.extra
+def do_boolean_sum(field):
+    """Wrapper to generate SUM on boolean values"""
+    cond = {field: True}
+    return Sum(
+        Case(
+            When(then=1, **cond),
+            default=0,
+            output_field=IntegerField()
         )
-        query.aggregates[alias] = aggregate
-
-    def _patch_aggregate(self, query):
-        """
-        Wrapper to disable compatibility layer in Django 1.8
-        """
-        return
-
-    @property
-    def template(self):
-        """
-        Returns template for the SQL
-
-        Used for Django 1.8 and newer
-        """
-        return get_template()
+    )

weblate/trans/migrations/0013_auto_20141124_1036.py

@@ -4,7 +4,7 @@ from __future__ import unicode_literals
 from django.db import migrations
 from django.db.models.aggregates import Sum
 
-from weblate.trans.boolean_sum import BooleanSum
+from weblate.trans.boolean_sum import do_boolean_sum
 
 
 def fill_in_have_comment(apps, schema_editor):
@@ -13,7 +13,7 @@ def fill_in_have_comment(apps, schema_editor):
     for translation in Translation.objects.all():
         stats = translation.unit_set.aggregate(
             Sum('num_words'),
-            BooleanSum('has_comment'),
+            has_comment__sum=do_boolean_sum('has_comment'),
         )
         if stats['num_words__sum'] is not None:
             translation.have_comment = int(stats['has_comment__sum'])

weblate/trans/models/translation.py

@@ -44,7 +44,7 @@ from weblate.trans.site import get_site_url
 from weblate.trans.util import translation_percent, split_plural
 from weblate.accounts.avatar import get_user_display
 from weblate.trans.mixins import URLMixin, PercentMixin, LoggerMixin
-from weblate.trans.boolean_sum import BooleanSum
+from weblate.trans.boolean_sum import do_boolean_sum
 from weblate.accounts.models import notify_new_string, get_author_name
 from weblate.trans.models.changes import Change
 from weblate.trans.checklists import TranslationChecklist
@@ -608,12 +608,12 @@ class Translation(models.Model, URLMixin, PercentMixin, LoggerMixin):
         # Grab stats
         stats = self.unit_set.aggregate(
             Sum('num_words'),
-            BooleanSum('fuzzy'),
-            BooleanSum('translated'),
-            BooleanSum('has_failing_check'),
-            BooleanSum('has_suggestion'),
-            BooleanSum('has_comment'),
             Count('id'),
+            fuzzy__sum=do_boolean_sum('fuzzy'),
+            translated__sum=do_boolean_sum('translated'),
+            has_failing_check__sum=do_boolean_sum('has_failing_check'),
+            has_suggestion__sum=do_boolean_sum('has_suggestion'),
+            has_comment__sum=do_boolean_sum('has_comment'),
         )
 
         # Check if we have any units