Allow search backends to be imported by module

This allows the elasticsearch backend to be imported like "wagtail.wagtailsearch.backends.elasticsearch" (dropping .ElasticSearch from the end of the import string)

docs/howto/settings.rst

@@ -162,7 +162,7 @@ Search
   # Replace the search backend
   WAGTAILSEARCH_BACKENDS = {
     'default': {
-      'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch.ElasticSearch',
+      'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch',
       'INDEX': 'myapp'
     }
   }
@@ -498,7 +498,7 @@ These two files should reside in your project directory (``myproject/myproject/`
   # Replace the search backend
   #WAGTAILSEARCH_BACKENDS = {
   #  'default': {
-  #    'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch.ElasticSearch',
+  #    'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch',
   #    'INDEX': 'myapp'
   #  }
   #}

docs/search/backends.rst

@@ -34,7 +34,7 @@ The backend is configured in settings:
 
   WAGTAILSEARCH_BACKENDS = {
       'default': {
-          'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch.ElasticSearch',
+          'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch',
           'URLS': ['http://localhost:9200'],
           'INDEX': 'wagtail',
           'TIMEOUT': 5,

wagtail/tests/settings.py

@@ -135,7 +135,7 @@ COMPRESS_ENABLED = False  # disable compression so that we can run tests on the
 
 WAGTAILSEARCH_BACKENDS = {
     'default': {
-        'BACKEND': 'wagtail.wagtailsearch.backends.db.DBSearch',
+        'BACKEND': 'wagtail.wagtailsearch.backends.db',
     }
 }
 
@@ -147,7 +147,7 @@ try:
 
     # Import succeeded, add an Elasticsearch backend
     WAGTAILSEARCH_BACKENDS['elasticsearch'] = {
-        'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch.ElasticSearch',
+        'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch',
         'TIMEOUT': 10,
         'max_retries': 1,
     }

wagtail/wagtailsearch/backends/__init__.py

@@ -2,6 +2,9 @@
 # Based on the Django cache framework
 # https://github.com/django/django/blob/5d263dee304fdaf95e18d2f0619d6925984a7f02/django/core/cache/__init__.py
 
+import sys
+import six
+from importlib import import_module
 
 from django.utils.module_loading import import_string
 from django.core.exceptions import ImproperlyConfigured
@@ -12,11 +15,34 @@ class InvalidSearchBackendError(ImproperlyConfigured):
     pass
 
 
+def import_backend(dotted_path):
+    """
+    Theres two formats for the dotted_path.
+    One with the backend class (old) and one without (new)
+    eg:
+      old: wagtail.wagtailsearch.backends.elasticsearch.ElasticSearch
+      new: wagtail.wagtailsearch.backends.elasticsearch
+
+    If a new style dotted path was specified, this function would
+    look for a backend class from the "SearchBackend" attribute.
+    """
+    try:
+        # New
+        backend_module = import_module(dotted_path)
+        return backend_module.SearchBackend
+    except ImportError as e:
+        try:
+            # Old
+            return import_string(dotted_path)
+        except ImportError:
+            six.reraise(ImportError, e, sys.exc_info()[2])
+
+
 def get_search_backend(backend='default', **kwargs):
     # Get configuration
     default_conf = {
         'default': {
-            'BACKEND': 'wagtail.wagtailsearch.backends.db.DBSearch',
+            'BACKEND': 'wagtail.wagtailsearch.backends.db',
         },
     }
     WAGTAILSEARCH_BACKENDS = getattr(
@@ -29,7 +55,7 @@ def get_search_backend(backend='default', **kwargs):
     except KeyError:
         try:
             # Trying to import the given backend, in case it's a dotted path
-            import_string(backend)
+            import_backend(backend)
         except ImportError as e:
             raise InvalidSearchBackendError("Could not find backend '%s': %s" % (
                 backend, e))
@@ -42,7 +68,7 @@ def get_search_backend(backend='default', **kwargs):
 
     # Try to import the backend
     try:
-        backend_cls = import_string(backend)
+        backend_cls = import_backend(backend)
     except ImportError as e:
         raise InvalidSearchBackendError("Could not find backend '%s': %s" % (
             backend, e))

wagtail/wagtailsearch/backends/db.py

@@ -93,3 +93,6 @@ class DBSearch(BaseSearch):
 
     def _search(self, queryset, query_string, fields=None):
         return DBSearchResults(self, DBSearchQuery(queryset, query_string, fields=fields))
+
+
+SearchBackend = DBSearch

wagtail/wagtailsearch/backends/elasticsearch.py

@@ -465,3 +465,6 @@ class ElasticSearch(BaseSearch):
 
     def _search(self, queryset, query_string, fields=None):
         return ElasticSearchResults(self, ElasticSearchQuery(queryset, query_string, fields=fields))
+
+
+SearchBackend = ElasticSearch

wagtail/wagtailsearch/tests/test_backends.py

@@ -133,7 +133,7 @@ class BackendTests(WagtailTestUtils):
 
 
 @override_settings(WAGTAILSEARCH_BACKENDS={
-    'default': {'BACKEND': 'wagtail.wagtailsearch.backends.db.DBSearch'}
+    'default': {'BACKEND': 'wagtail.wagtailsearch.backends.db'}
 })
 class TestBackendLoader(TestCase):
     def test_import_by_name(self):
@@ -141,11 +141,15 @@ class TestBackendLoader(TestCase):
         self.assertIsInstance(db, DBSearch)
 
     def test_import_by_path(self):
+        db = get_search_backend(backend='wagtail.wagtailsearch.backends.db')
+        self.assertIsInstance(db, DBSearch)
+
+    def test_import_by_full_path(self):
         db = get_search_backend(backend='wagtail.wagtailsearch.backends.db.DBSearch')
         self.assertIsInstance(db, DBSearch)
 
     def test_nonexistent_backend_import(self):
-        self.assertRaises(InvalidSearchBackendError, get_search_backend, backend='wagtail.wagtailsearch.backends.doesntexist.DoesntExist')
+        self.assertRaises(InvalidSearchBackendError, get_search_backend, backend='wagtail.wagtailsearch.backends.doesntexist')
 
     def test_invalid_backend_import(self):
         self.assertRaises(InvalidSearchBackendError, get_search_backend, backend="I'm not a backend!")

wagtail/wagtailsearch/tests/test_db_backend.py

@@ -6,7 +6,7 @@ from .test_backends import BackendTests
 
 
 class TestDBBackend(BackendTests, TestCase):
-    backend_path = 'wagtail.wagtailsearch.backends.db.DBSearch'
+    backend_path = 'wagtail.wagtailsearch.backends.db'
 
     @unittest.expectedFailure
     def test_callable_indexed_field(self):

wagtail/wagtailsearch/tests/test_elasticsearch_backend.py

@@ -13,7 +13,7 @@ from .test_backends import BackendTests
 
 
 class TestElasticSearchBackend(BackendTests, TestCase):
-    backend_path = 'wagtail.wagtailsearch.backends.elasticsearch.ElasticSearch'
+    backend_path = 'wagtail.wagtailsearch.backends.elasticsearch'
 
     def test_search_with_spaces_only(self):
         # Search for some space characters and hope it doesn't crash