Adds alias for grouping by multiple related fields

flask_restless/search/drivers.py

@@ -130,7 +130,7 @@ def search(session, model, filters=None, sort=None, group_by=None,
         for field_name in group_by:
             if '.' in field_name:
                 field_name, field_name_in_relation = field_name.split('.')
-                relation_model = get_related_model(model, field_name)
+                relation_model = aliased(get_related_model(model, field_name))
                 field = getattr(relation_model, field_name_in_relation)
                 query = query.join(relation_model)
                 query = query.group_by(field)

tests/test_fetching.py

@@ -18,6 +18,7 @@
 specification.
 
 """
+from itertools import product
 from operator import itemgetter
 from unittest2 import skip
 
@@ -50,6 +51,7 @@ def setUp(self):
         class Person(self.Base):
             __tablename__ = 'person'
             id = Column(Integer, primary_key=True)
+            age = Column(Integer)
             name = Column(Unicode)
 
         class Article(self.Base):
@@ -187,13 +189,34 @@ def test_group_by_related(self):
         article3.author = person2
         self.session.add_all([person1, person2, article1, article2, article3])
         self.session.commit()
-        response = self.app.get('/api/article?group=author.name')
+        query_string = {'group': 'author.name'}
+        response = self.app.get('/api/article', query_string=query_string)
         document = loads(response.data)
         articles = document['data']
         author_ids = sorted(article['relationships']['author']['data']['id']
                             for article in articles)
         assert ['1', '2'] == author_ids
 
+    def test_group_by_mutiple_relationship_attributes(self):
+        """Tests for grouping results by multiple fields of a related model."""
+        names = [u'foo', u'bar']
+        ages = [10, 20]
+        # There are two people with each combination of name and age.
+        for i, (name, age) in enumerate(product(names, ages), start=1):
+            person1 = self.Person(id=2 * i - 1, name=name, age=age)
+            person2 = self.Person(id=2 * i, name=name, age=age)
+            article1 = self.Article(author=person1)
+            article2 = self.Article(author=person2)
+            self.session.add_all([article1, article2, person1, person2])
+        self.session.commit()
+        query_string = {'group': ','.join(['author.name', 'author.age'])}
+        response = self.app.get('/api/article', query_string=query_string)
+        document = loads(response.data)
+        articles = document['data']
+        author_ids = sorted(article['relationships']['author']['data']['id']
+                            for article in articles)
+        assert ['2', '4', '6', '8'] == author_ids
+
     def test_pagination_links_empty_collection(self):
         """Tests that pagination links work correctly for an empty
         collection.