Make add_pageblock_from_dict more flexible

This allows you to pass a pageblock instance to
`add_pageblock_from_dict`, as well as a dictionary.

For a complex custom pageblock, it can be simplest to initialize it
on its own with a factory, and then pass it into a call to
`add_child_section_from_dict`, similar to here:
http://django-pagetree.readthedocs.org/en/latest/testing.html

referencing issue #92

pagetree/generic/models.py

@@ -20,6 +20,13 @@ class Meta:
     display_name = None
     """The name for this block that's used in pagetree's menus."""
 
+    def as_dict(self):
+        """Returns the PageBlock as a dictionary.
+
+        :rtype: dictionary
+        """
+        return dict(block_type=self.display_name)
+
     def allow_redo(self):
         """Determines whether this block allows users to resubmit answers.
 

pagetree/models.py

@@ -538,7 +538,14 @@ def from_dict(self, d):
             self.add_child_section_from_dict(c)
 
     def add_pageblock_from_dict(self, d):
-        target_type = d.get('block_type', '')
+        try:
+            target_type = d.get('block_type', '')
+        except AttributeError:
+            # If we can't call .get on the dictionary,
+            # it must not be a dictionary. Assume it's a pageblock,
+            # and turn it into a dict here.
+            d = d.as_dict()
+            target_type = d.get('block_type', '')
 
         # now we need to figure out which kind of pageblock to create
         found_pbclass = None

pagetree/test_models.py

@@ -67,7 +67,9 @@ def edit(self, vals, files):
         self.save()
 
     def as_dict(self):
-        return dict(body=self.body)
+        d = super(TestBlock, self).as_dict()
+        d['body'] = self.body
+        return d
 
     def import_from_dict(self, d):
         self.body = d.get('body', '')

pagetree/tests/factories.py

@@ -7,7 +7,7 @@
 
 class UserFactory(factory.DjangoModelFactory):
     class Meta:
-        model  = User
+        model = User
 
     username = factory.Sequence(lambda n: "user%03d" % n)
     password = factory.PostGenerationMethodCall('set_password', 'test')

pagetree/tests/test_models.py

@@ -765,6 +765,17 @@ def test_add_pageblock_from_dict(self):
         block = self.section.pageblock_set.first()
         assert(block is not None)
         self.assertEqual(block.block().body, 'test body')
+        self.assertEqual(
+            self.section.pageblock_set.first(), block,
+            'The PageBlock has been added to the Section')
+
+    def test_add_pageblock_from_dict_instance(self):
+        testblock = TestBlockFactory()
+        self.section.add_pageblock_from_dict(testblock)
+        self.assertEqual(
+            self.section.pageblock_set.first().block().display_name,
+            testblock.display_name,
+            'The PageBlock has been added to the Section')
 
     def test_empty_section_is_unlocked(self):
         self.assertTrue(self.section.unlocked(self.user))