Optimize ElasticSearch backend (closes django-haystack#1590)

Thanks to @klass-ivan for the patch

Author: acdha

haystack/backends/elasticsearch_backend.py

@@ -625,8 +625,8 @@ def from_timestamp(tm):
             model = haystack_get_model(app_label, model_name)
 
             if model and model in indexed_models:
+                index = source and unified_index.get_index(model)
                 for key, value in source.items():
-                    index = unified_index.get_index(model)
                     string_key = str(key)
 
                     if string_key in index.fields and hasattr(index.fields[string_key], 'convert'):

test_haystack/elasticsearch_tests/test_elasticsearch_backend.py

@@ -5,6 +5,7 @@
 import logging as std_logging
 import operator
 import unittest
+from contextlib import contextmanager
 from decimal import Decimal
 
 import elasticsearch
@@ -229,6 +230,24 @@ def test_kwargs_are_passed_on(self):
         self.assertEqual(backend.conn.transport.max_retries, 42)
 
 
+class ElasticSearchMockUnifiedIndex(UnifiedIndex):
+
+    spy_args = None
+
+    def get_index(self, model_klass):
+        if self.spy_args is not None:
+            self.spy_args.setdefault('get_index', []).append(model_klass)
+        return super(ElasticSearchMockUnifiedIndex, self).get_index(model_klass)
+
+    @contextmanager
+    def spy(self):
+        try:
+            self.spy_args = {}
+            yield self.spy_args
+        finally:
+            self.spy_args = None
+
+
 class ElasticsearchSearchBackendTestCase(TestCase):
     def setUp(self):
         super(ElasticsearchSearchBackendTestCase, self).setUp()
@@ -239,7 +258,7 @@ def setUp(self):
 
         # Stow.
         self.old_ui = connections['elasticsearch'].get_unified_index()
-        self.ui = UnifiedIndex()
+        self.ui = ElasticSearchMockUnifiedIndex()
         self.smmi = ElasticsearchMockSearchIndex()
         self.smmidni = ElasticsearchMockSearchIndexWithSkipDocument()
         self.smtmmi = ElasticsearchMaintainTypeMockSearchIndex()
@@ -412,6 +431,13 @@ def test_clear(self):
         self.sb.clear([AnotherMockModel, MockModel])
         self.assertEqual(self.raw_search('*:*').get('hits', {}).get('total', 0), 0)
 
+    def test_results_ask_for_index_per_entry(self):
+        # Test that index class is obtained per result entry, not per every entry field
+        self.sb.update(self.smmi, self.sample_objs)
+        with self.ui.spy() as spy:
+            self.sb.search('*:*', limit_to_registered_models=False)
+            self.assertEqual(len(spy.get('get_index', [])), len(self.sample_objs))
+
     def test_search(self):
         self.sb.update(self.smmi, self.sample_objs)
         self.assertEqual(self.raw_search('*:*')['hits']['total'], 3)