Fixed case where SearchQuerySet.more_like_this would fail when usin…

…g deferred Models. Thanks to Alex Gaynor for the original patch.

AUTHORS

@@ -29,3 +29,4 @@ Thanks to
     * Frank Wiles for documentation patches.
     * Chris Adams (acdha) for various patches.
     * Kyle MacFarlane for various patches.
+    * Alex Gaynor (alex) for help with handling deferred models with More Like This.

haystack/backends/solr_backend.py

@@ -3,6 +3,7 @@
 from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
 from django.db.models.loading import get_model
+from django.db.models.sql.query import get_proxied_model
 from django.utils.encoding import force_unicode
 from haystack.backends import BaseSearchBackend, BaseSearchQuery, log_query
 from haystack.exceptions import MissingDependency, MoreLikeThisError
@@ -184,7 +185,13 @@ def search(self, query_string, sort_by=None, start_offset=0, end_offset=None,
     def more_like_this(self, model_instance, additional_query_string=None,
                        start_offset=0, end_offset=None,
                        limit_to_registered_models=True, **kwargs):
-        index = self.site.get_index(model_instance.__class__)
+        # Handle deferred models.
+        if hasattr(model_instance, '_deferred') and model_instance._deferred:
+            model_klass = get_proxied_model(model_instance._meta)
+        else:
+            model_klass = type(model_instance)
+
+        index = self.site.get_index(model_klass)
         field_name = index.get_content_field()
         params = {
             'fl': '*,score',

tests/solr_tests/tests/solr_backend.py

@@ -535,6 +535,14 @@ def test_more_like_this(self):
         alt_mlt_with_models = self.sqs.models(MockModel).more_like_this(MockModel.objects.get(pk=1))
         self.assertEqual(alt_mlt_with_models.count(), 23)
         self.assertEqual([result.pk for result in alt_mlt_with_models], ['6', '14', '4', '10', '22', '5', '3', '12', '2', '23', '18', '19', '13', '7', '15', '21', '9', '20', '16', '17', '8', '11'])
+
+        if hasattr(MockModel.objects, 'defer'):
+            # Make sure MLT works with deferred bits.
+            mi = MockModel.objects.defer('foo').get(pk=1)
+            self.assertEqual(mi._deferred, True)
+            deferred = self.sqs.models(MockModel).more_like_this(mi)
+            self.assertEqual(alt_mlt_with_models.count(), 23)
+            self.assertEqual([result.pk for result in alt_mlt_with_models], ['6', '14', '4', '10', '22', '5', '3', '12', '2', '23', '18', '19', '13', '7', '15', '21', '9', '20', '16', '17', '8', '11'])
 
 
 class SolrRoundTripSearchIndex(indexes.RealTimeSearchIndex):