Add generic support for multilingual search engines through Haystack

multilingual_haystack/backends.py

@@ -0,0 +1,71 @@
+# based on http://anthony-tresontani.github.io/Django/2012/09/20/multilingual-search/
+import re
+from django.conf import settings
+from django.utils import translation
+from haystack import connections
+from haystack.backends import BaseEngine, BaseSearchBackend, BaseSearchQuery
+from haystack.constants import DEFAULT_ALIAS
+from haystack.utils.loading import load_backend
+
+
+def get_using(language, alias=DEFAULT_ALIAS):
+    new_using = alias + "-" + language
+    using = new_using if new_using in settings.HAYSTACK_CONNECTIONS else alias
+    return using
+
+class MultilingualSearchBackend(BaseSearchBackend):
+    def update(self, index, iterable, commit=True):
+        initial_language = translation.get_language()[:2]
+        # retrieve unique backend name
+        backends = []
+        for language, _ in settings.LANGUAGES:
+            using = '%s-%s' % (self.connection_alias, language)
+            # Ensure each backend is called only once
+            if using in backends:
+                continue
+            else:
+                backends.append(using)
+            translation.activate(language)
+            backend = connections[using].get_backend()
+            backend.parent_class.update(backend, index, iterable, commit)
+
+        translation.activate(initial_language)
+    def clear(self, **kwargs):
+        return
+
+class MultilingualSearchQuery(BaseSearchQuery):
+    def __init__(self, using=DEFAULT_ALIAS):
+        language = translation.get_language()[:2]
+        using = get_using(language)
+        super(MultilingualSearchQuery, self).__init__(using=using)
+
+class LanguageSearchBackend(BaseSearchBackend):
+    def update(self, *args, **kwargs):
+        # Handle all updates through the main Multilingual object.
+        return
+
+class LanguageSearchQuery(BaseSearchQuery):
+    def __init__(self, **kwargs):
+        pass
+
+class LanguageSearchEngine(BaseEngine):
+    def __init__(self, **kwargs):
+        conn_config = settings.HAYSTACK_CONNECTIONS[kwargs['using']]
+        base_engine = load_backend(conn_config['BASE_ENGINE'])(**kwargs)
+
+        backend_bases = (LanguageSearchBackend, base_engine.backend)
+        backend_class = type('LanguageSearchBackend', backend_bases,
+                             {'parent_class': base_engine.backend})
+        self.backend = backend_class
+
+        query_bases = (LanguageSearchQuery, base_engine.query)
+        query_class = type('LanguageSearchQuery', query_bases,
+                           {'parent_class': base_engine.query})
+        self.query = query_class
+
+        super(LanguageSearchEngine, self).__init__(**kwargs)
+
+
+class MultilingualSearchEngine(BaseEngine):
+    backend = MultilingualSearchBackend
+    query = MultilingualSearchQuery