Ensured BaseSearchBackend.search method always return BaseSearchResults subclasses

wagtail/api/v2/pagination.py

@@ -3,12 +3,9 @@ from __future__ import absolute_import, unicode_literals
 from collections import OrderedDict
 
 from django.conf import settings
-from django.db.models.query import QuerySet
 from rest_framework.pagination import BasePagination
 from rest_framework.response import Response
 
-from wagtail.wagtailsearch.backends.base import BaseSearchResults
-
 from .utils import BadRequestError
 
 
@@ -36,7 +33,7 @@ class WagtailPagination(BasePagination):
         stop = offset + limit
 
         self.view = view
-        self.total_count = queryset.count() if isinstance(queryset, (BaseSearchResults, QuerySet)) else len(queryset)
+        self.total_count = queryset.count()
         return queryset[start:stop]
 
     def get_paginated_response(self, data):

wagtail/contrib/wagtailapi/pagination.py

@@ -3,12 +3,9 @@ from __future__ import absolute_import, unicode_literals
 from collections import OrderedDict
 
 from django.conf import settings
-from django.db.models.query import QuerySet
 from rest_framework.pagination import BasePagination
 from rest_framework.response import Response
 
-from wagtail.wagtailsearch.backends.base import BaseSearchResults
-
 from .utils import BadRequestError
 
 
@@ -36,7 +33,7 @@ class WagtailPagination(BasePagination):
         stop = offset + limit
 
         self.view = view
-        self.total_count = queryset.count() if isinstance(queryset, (BaseSearchResults, QuerySet)) else len(queryset)
+        self.total_count = queryset.count()
         return queryset[start:stop]
 
     def get_paginated_response(self, data):

wagtail/wagtailsearch/backends/base.py

@@ -186,6 +186,20 @@ class BaseSearchResults(object):
         return clone
 
 
+class EmptySearchResults(BaseSearchResults):
+    def __init__(self):
+        return super(EmptySearchResults, self).__init__(None, None)
+
+    def _clone(self):
+        return self.__class__()
+
+    def _do_search(self):
+        return []
+
+    def _do_count(self):
+        return 0
+
+
 class BaseSearchBackend(object):
     query_class = None
     results_class = None
@@ -230,11 +244,11 @@ class BaseSearchBackend(object):
 
         # Model must be a class that is in the index
         if not class_is_indexed(model):
-            return []
+            return EmptySearchResults()
 
         # Check that theres still a query string after the clean up
         if query_string == "":
-            return []
+            return EmptySearchResults()
 
         # Only fields that are indexed as a SearchField can be passed in fields
         if fields: