Add unaccent to SearchFilter (based on encode#7733)

Author: mgaligniana

docs/api-guide/filtering.md

@@ -230,6 +230,7 @@ The search behavior may be specified by prefixing field names in `search_fields`
 | `$`    | `iregex`      | Regex search.      |
 | `@`    | `search`      | Full-text search (Currently only supported Django's [PostgreSQL backend][postgres-search]). |
 | None   | `icontains`   | Contains search (Default).  |
+| `&`    | `unaccent`    | Accent-insensitive search. (Currently only supported Django's [PostgreSQL backend][postgres-lookups]). |
 
 For example:
 
@@ -370,3 +371,4 @@ The [djangorestframework-word-filter][django-rest-framework-word-search-filter]
 [HStoreField]: https://docs.djangoproject.com/en/3.0/ref/contrib/postgres/fields/#hstorefield
 [JSONField]: https://docs.djangoproject.com/en/3.0/ref/contrib/postgres/fields/#jsonfield
 [postgres-search]: https://docs.djangoproject.com/en/stable/ref/contrib/postgres/search/
+[postgres-lookups]: https://docs.djangoproject.com/en/stable/ref/contrib/postgres/lookups/#unaccent

rest_framework/filters.py

@@ -68,6 +68,7 @@ class SearchFilter(BaseFilterBackend):
         '=': 'iexact',
         '@': 'search',
         '$': 'iregex',
+        '&': 'unaccent',
     }
     search_title = _('Search')
     search_description = _('A search term.')

tests/test_filters.py

@@ -10,7 +10,7 @@
 from django.test.utils import override_settings
 
 from rest_framework import filters, generics, serializers
-from rest_framework.compat import coreschema
+from rest_framework.compat import coreschema, postgres_fields
 from rest_framework.exceptions import ValidationError
 from rest_framework.test import APIRequestFactory
 
@@ -146,6 +146,23 @@ class SearchListView(generics.ListAPIView):
             {'id': 2, 'title': 'zz', 'text': 'bcd'}
         ]
 
+    @pytest.mark.skipif(not postgres_fields, reason='psycopg2 is not installed')
+    def test_unaccent_search(self):
+        class SearchListView(generics.ListAPIView):
+            queryset = SearchFilterModel.objects.all()
+            serializer_class = SearchFilterSerializer
+            filter_backends = (filters.SearchFilter,)
+            search_fields = ('title', '&text')
+
+        obj = SearchFilterModel(title='Accent títle', text='Accent téxt').save()
+        view = SearchListView.as_view()
+        lower_and_unaccent_text = 'accent text'
+        request = factory.get('/', {'search': lower_and_unaccent_text})
+        response = view(request)
+        assert response.data == [
+            {'id': obj.id, 'title': 'Accent títle', 'text': 'Accent téxt'}
+        ]
+
     def test_regexp_search(self):
         class SearchListView(generics.ListAPIView):
             queryset = SearchFilterModel.objects.all()