[soc2010/query-refactor] Fixed Querysets in MongoDB with a limit of 0.

alex · alex · commit d6993c7dbb4f · 2010-06-22T18:09:08.000Z
git-svn-id: http://code.djangoproject.com/svn/django/branches/soc2010/query-refactor@13382 bcc190cf-cafb-0310-a4f2-bffc1f526a37
diff --git a/django/contrib/mongodb/compiler.py b/django/contrib/mongodb/compiler.py
@@ -1,6 +1,6 @@
 from pymongo import ASCENDING, DESCENDING
 
-from django.db.models.sql.datastructures import FullResultSet
+from django.db.models.sql.datastructures import FullResultSet, EmptyResultSet
 
 
 # TODO: ...
@@ -87,11 +87,16 @@ def build_query(self, aggregates=False):
         if self.query.low_mark:
             cursor = cursor.skip(self.query.low_mark)
         if self.query.high_mark is not None:
+            if self.query.high_mark - self.query.low_mark == 0:
+                raise EmptyResultSet
             cursor = cursor.limit(self.query.high_mark - self.query.low_mark)
         return cursor
     
     def results_iter(self):
-        query = self.build_query()
+        try:
+            query = self.build_query()
+        except EmptyResultSet:
+            return
         fields = self.get_fields(aggregates=False)
         if fields is None:
             fields = [
diff --git a/tests/regressiontests/mongodb/tests.py b/tests/regressiontests/mongodb/tests.py
@@ -95,8 +95,7 @@ def test_slicing(self):
         ]
         
         for i in xrange(5):
-            # TODO: should be i, but Mongo falls over with limit(0)
-            for j in xrange(i+1, 5):
+            for j in xrange(i, 5):
                 self.assertQuerysetEqual(
                     Artist.objects.all()[i:j],
                     artists[i:j],

Original file line number	Diff line number	Diff line change
`@@ -95,8 +95,7 @@ def test_slicing(self):`
`95`	`95`	`]`
`96`	`96`
`97`	`97`	`for i in xrange(5):`
`98`		`- # TODO: should be i, but Mongo falls over with limit(0)`
`99`		`- for j in xrange(i+1, 5):`
	`98`	`+ for j in xrange(i, 5):`
`100`	`99`	`self.assertQuerysetEqual(`
`101`	`100`	`Artist.objects.all()[i:j],`
`102`	`101`	`artists[i:j],`