call save when deserializing cells (#15673)

combo/data/models.py

@@ -340,6 +340,8 @@ class Page(models.Model):
         # load new cells
         for cell in serializers.deserialize('json', json.dumps(cells)):
             cell.save()
+            # will populate cached_* attributes
+            cell.object.save()
 
     @classmethod
     def load_serialized_pages(cls, json_site):

tests/test_wcs.py

@@ -258,6 +258,24 @@ def test_form_cell_save_cache():
          'url': 'http://127.0.0.1:8999/form-title/',
          'text': ''}]
 
+
+@wcsctl_present
+def test_form_cell_load():
+    page = Page(title='xxx', slug='test_form_cell_save_cache', template_name='standard')
+    page.save()
+    cell = WcsFormCell(page=page, placeholder='content', order=0)
+    cell.formdef_reference = u'default:form-title'
+    cell.save()
+    site_export = [page.get_serialized_page()]
+    cell.delete()
+    assert not page.get_cells()
+    Page.load_serialized_pages(site_export)
+    cells = page.get_cells()
+    assert len(cells) == 1
+    cell = cells[0]
+    assert cell.cached_title == 'form title'
+
+
 @wcsctl_present
 def test_category_cell_save_cache():
     page = Page(title='xxx', slug='test_category_cell_save_cache', template_name='standard')