Clarify the use of SelfAttribute in RelatedFactory (Closes #264)

2 files changed, 47 insertions, 0 deletions

diff --git a/docs/reference.rst b/docs/reference.rst
index 6398d9a..b5ccd16 100644
--- a/docs/reference.rst
+++ b/docs/reference.rst
@@ -1412,6 +1412,23 @@ If a value if passed for the :class:`RelatedFactory` attribute, this disables
     1
 
 
+.. note:: The target of the :class:`RelatedFactory` is evaluated *after* the initial factory has been instantiated.
+          This means that calls to :class:`factory.SelfAttribute` cannot go higher than this :class:`RelatedFactory`:
+
+          .. code-block:: python
+
+              class CountryFactory(factory.Factory):
+                  class Meta:
+                      model = Country
+
+                  lang = 'fr'
+                  capital_city = factory.RelatedFactory(CityFactory, 'capital_of',
+                      # factory.SelfAttribute('..lang') will crash, since the context of
+                      # ``CountryFactory`` has already been evaluated.
+                      main_lang=factory.SelfAttribute('capital_of.lang'),
+                  )
+
+
 PostGeneration
 """"""""""""""
 
diff --git a/tests/test_using.py b/tests/test_using.py
index c7d2b85..0a893c1 100644
--- a/tests/test_using.py
+++ b/tests/test_using.py
@@ -1924,6 +1924,36 @@ class PostGenerationTestCase(unittest.TestCase):
         self.assertEqual(3, related.one)
         self.assertEqual(4, related.two)
 
+    def test_related_factory_selfattribute(self):
+        class TestRelatedObject(object):
+            def __init__(self, obj=None, one=None, two=None):
+                obj.related = self
+                self.one = one
+                self.two = two
+                self.three = obj
+
+        class TestRelatedObjectFactory(factory.Factory):
+            class Meta:
+                model = TestRelatedObject
+            one = 1
+            two = factory.LazyAttribute(lambda o: o.one + 1)
+
+        class TestObjectFactory(factory.Factory):
+            class Meta:
+                model = TestObject
+            one = 3
+            two = 2
+            three = factory.RelatedFactory(TestRelatedObjectFactory, 'obj',
+                two=factory.SelfAttribute('obj.two'),
+            )
+
+        obj = TestObjectFactory.build(two=4)
+        self.assertEqual(3, obj.one)
+        self.assertEqual(4, obj.two)
+        self.assertEqual(1, obj.related.one)
+        self.assertEqual(4, obj.related.two)
+
+
 
 class RelatedFactoryExtractionTestCase(unittest.TestCase):
     def setUp(self):