Added get_indexed_instance method

When a signal handler is run on a model that is the parent in a multi
table inheritance relationship, we do not have access to all of the
fields we need to properly reindex the object.

This commit adds a method that the developer can use to specify how to
get the specific type of a particular instance which we can use to
reindex it.

wagtail/tests/models.py

@@ -429,14 +429,24 @@ class SearchTest(models.Model, index.Indexed):
     def get_indexed_objects(cls):
         indexed_objects = super(SearchTest, cls).get_indexed_objects()
 
-        # Exclude SearchTests that have a SearchTestChild to prevent duplicates
+        # Exclude SearchTests that have a SearchTestChild to stop update_index creating duplicates
         if cls is SearchTest:
             indexed_objects = indexed_objects.exclude(
                 id__in=SearchTestChild.objects.all().values_list('searchtest_ptr_id', flat=True)
             )
 
+        # Exclude SearchTests that have the title "Don't index me!"
+        indexed_objects = indexed_objects.exclude(title="Don't index me!")
+
         return indexed_objects
 
+    def get_indexed_instance(self):
+        # Check if there is a SearchTestChild that descends from this
+        child = SearchTestChild.objects.filter(searchtest_ptr_id=self.id).first()
+
+        # Return the child if there is one, otherwise return self
+        return child or self
+
 class SearchTestChild(SearchTest):
     subtitle = models.CharField(max_length=255, null=True, blank=True)
     extra_content = models.TextField()

wagtail/wagtailcore/models.py

@@ -564,6 +564,9 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
         content_type = ContentType.objects.get_for_model(cls)
         return super(Page, cls).get_indexed_objects().filter(content_type=content_type)
 
+    def get_indexed_instance(self):
+        return self.specific
+
     @classmethod
     def search(cls, query_string, show_unpublished=False, search_title_only=False, extra_filters={}, prefetch_related=[], path=None):
         # Filters

wagtail/wagtailsearch/index.py

@@ -51,6 +51,13 @@ class Indexed(object):
     def get_indexed_objects(cls):
         return cls.objects.all()
 
+    def get_indexed_instance(self):
+        """
+        If the indexed model uses multi table inheritance, override this method
+        to return the instance in its most specific class so it reindexes properly.
+        """
+        return self
+
     search_fields = ()
 
 

wagtail/wagtailsearch/signal_handlers.py

@@ -5,21 +5,30 @@ from wagtail.wagtailsearch.index import Indexed
 from wagtail.wagtailsearch.backends import get_search_backends
 
 
-def post_save_signal_handler(instance, **kwargs):
-    if not type(instance).get_indexed_objects().filter(id=instance.id).exists():
+def get_indexed_instance(instance):
+    indexed_instance = instance.get_indexed_instance()
+
+    # Make sure that the instance is in it's classes indexed objects
+    if not type(indexed_instance).get_indexed_objects().filter(id=indexed_instance.id).exists():
         return
 
+    return indexed_instance
 
-    for backend in get_search_backends():
-        backend.add(instance)
+
+def post_save_signal_handler(instance, **kwargs):
+    indexed_instance = get_indexed_instance(instance)
+
+    if indexed_instance:
+        for backend in get_search_backends():
+            backend.add(indexed_instance)
 
 
 def post_delete_signal_handler(instance, **kwargs):
-    if not type(instance).get_indexed_objects().filter(id=instance.id).exists():
-        return
+    indexed_instance = get_indexed_instance(instance)
 
-    for backend in get_search_backends():
-        backend.delete(instance)
+    if indexed_instance:
+        for backend in get_search_backends():
+            backend.delete(indexed_instance)
 
 
 def register_signal_handlers():

wagtail/wagtailsearch/tests/test_signal_handlers.py

@@ -0,0 +1,40 @@
+from django.test import TestCase
+
+from wagtail.wagtailsearch import signal_handlers
+from wagtail.tests import models
+
+
+class TestGetIndexedInstance(TestCase):
+    def test_gets_instance(self):
+        obj = models.SearchTest(
+            title="Hello",
+            live=True,
+        )
+        obj.save()
+
+        # Should just return the object
+        indexed_instance = signal_handlers.get_indexed_instance(obj)
+        self.assertEqual(indexed_instance, obj)
+
+    def test_gets_specific_class(self):
+        obj = models.SearchTestChild(
+            title="Hello",
+            live=True,
+        )
+        obj.save()
+
+        # Running the command with the parent class should find the specific class again
+        indexed_instance = signal_handlers.get_indexed_instance(obj.searchtest_ptr)
+        self.assertEqual(indexed_instance, obj)
+
+    def test_blocks_not_in_indexed_objects(self):
+        obj = models.SearchTestChild(
+            title="Don't index me!",
+            live=True,
+        )
+        obj.save()
+
+        # We've told it not to index anything with the title "Don't index me"
+        # get_indexed_instance should return None
+        indexed_instance = signal_handlers.get_indexed_instance(obj.searchtest_ptr)
+        self.assertEqual(indexed_instance, None)