many2many stuff

fkreplace/__init__.py

@@ -17,9 +17,12 @@ def merge(from_obj, to_obj):
             import pdb; pdb.set_trace()
             raise Exception('unknown code path')
 
-    for related_m2m in from_obj._meta.get_all_related_many_to_many_objects():
+    for related in from_obj._meta.get_all_related_many_to_many_objects():
         accessor_name = related.get_accessor_name()
+        if accessor_name:
             varname = related.field.name
-
-        #for obj in getattr(from_obj, varname)
-
+            field = getattr(from_obj, accessor_name)
+            if related.many_to_many:
+                for f in field.all():
+                    getattr(f, varname).remove(from_obj)
+                    getattr(f, varname).add(to_obj)

tests/models.py

@@ -18,4 +18,4 @@ class SSN(models.Model):
 
 class Group(models.Model):
     name = models.CharField(max_length=100)
-    people = models.ManyToManyField(Person)
+    people = models.ManyToManyField(Person, related_name='groups')

tests/tests.py

@@ -37,3 +37,27 @@ class MergeTests(TestCase):
         c = Person.objects.get(pk=self.c.pk)
         c.ssn.number == 1
         assert SSN.objects.count() == 2
+
+    # TODO: test one2one when there's a conflict
+
+    def test_many2many_simple(self):
+        merge(self.a, self.c)
+        # A's membership in G has been moved to C
+        assert self.g.people.all().count() == 2
+        assert self.a.groups.all().count() == 0
+        assert self.c.groups.all().count() == 1
+
+    def test_many2many_redundant(self):
+        merge(self.a, self.b)
+        # A's membership in G is redundant with B's
+        assert self.g.people.all().count() == 1
+        assert self.a.groups.all().count() == 0
+        assert self.b.groups.all().count() == 1
+
+    def test_many2many_self(self):
+        self.a.friends.add(self.b)
+        merge(self.a, self.c)
+        import pdb; pdb.set_trace()
+        assert self.a.friends.all().count() == 0
+        assert self.b.friends.get().name == self.c
+        assert self.c.friends.get().name == self.b