Ignoring empty query string parameters sent to search endpoint (#352)

These empty parameters cause errors, resulting in failed responses.

ECOM-5685

course_discovery/apps/api/filters.py

@@ -59,14 +59,34 @@ class FacetQueryBuilderWithQueries(FacetQueryBuilder):
         return query
 
 
-class HaystackFacetFilterWithQueries(HaystackFacetFilter):
+class HaystackRequestFilterMixin:
+    @staticmethod
+    def get_request_filters(request):
+        filters = HaystackFacetFilter.get_request_filters(request)
+
+        # Remove items with empty values.
+        #
+        # NOTE 1: We copy the keys list to avoid a RuntimeError that occurs when modifying a dict while iterating.
+        #
+        # NOTE 2: We filter in this fashion, as opposed to dictionary comprehension, due to the fact that filters
+        # is a `QueryDict` object, not a `dict`. Dictionary comprehension will not preserve the values of
+        # `QueryDict.getlist()`. Since we support multiple values for a single parameter, dictionary comprehension is a
+        # dealbreaker (and production breaker).
+        for key in list(filters.keys()):
+            if not filters[key]:
+                del filters[key]
+
+        return filters
+
+
+class HaystackFacetFilterWithQueries(HaystackRequestFilterMixin, HaystackFacetFilter):
     query_builder_class = FacetQueryBuilderWithQueries
 
 
-class HaystackFilter(DefaultHaystackFilter):
+class HaystackFilter(HaystackRequestFilterMixin, DefaultHaystackFilter):
     @staticmethod
     def get_request_filters(request):
-        filters = HaystackFacetFilter.get_request_filters(request)
+        filters = HaystackRequestFilterMixin.get_request_filters(request)
 
         # Return data for the default partner, if no partner is requested
         if not any(field in filters for field in ('partner', 'partner_exact')):

course_discovery/apps/api/tests/test_filters.py

+import ddt
+from django.test import TestCase
+from rest_framework.test import APIRequestFactory
+from rest_framework.views import APIView
+
+from course_discovery.apps.api.filters import HaystackRequestFilterMixin
+
+
+@ddt.ddt
+class HaystackRequestFilterMixinTests(TestCase):
+    def test_get_request_filters(self):
+        """ Verify the method removes query parameters with empty values """
+        request = APIRequestFactory().get('/?q=')
+        request = APIView().initialize_request(request)
+        filters = HaystackRequestFilterMixin.get_request_filters(request)
+        self.assertDictEqual(filters, {})
+
+    def test_get_request_filters_with_list(self):
+        """ Verify the method does not affect list values. """
+        request = APIRequestFactory().get('/?q=&content_type=courserun&content_type=program')
+        request = APIView().initialize_request(request)
+        filters = HaystackRequestFilterMixin.get_request_filters(request)
+        self.assertNotIn('q', filters)
+        self.assertEqual(filters.getlist('content_type'), ['courserun', 'program'])
+
+    def test_get_request_filters_with_falsey_values(self):
+        """ Verify the method does not strip valid falsey values. """
+        request = APIRequestFactory().get('/?q=&test=0')
+        request = APIView().initialize_request(request)
+        filters = HaystackRequestFilterMixin.get_request_filters(request)
+        self.assertNotIn('q', filters)
+        self.assertEqual(filters.get('test'), '0')

course_discovery/apps/api/v1/tests/test_views/test_search.py

@@ -236,3 +236,15 @@ class AggregateSearchViewSet(DefaultPartnerMixin, SerializationMixin, LoginMixin
         response_data = json.loads(response.content.decode('utf-8'))
         self.assertListEqual(response_data['objects']['results'],
                              [self.serialize_course_run(other_course_run), self.serialize_program(other_program)])
+
+    def test_empty_query(self):
+        """ Verify, when the query (q) parameter is empty, the endpoint behaves as if the parameter
+        was not provided. """
+        course_run = CourseRunFactory(course__partner=self.partner, status=CourseRunStatus.Published)
+        program = ProgramFactory(partner=self.partner, status=ProgramStatus.Active)
+
+        response = self.get_search_response({'q': '', 'content_type': ['courserun', 'program']})
+        self.assertEqual(response.status_code, 200)
+        response_data = json.loads(response.content.decode('utf-8'))
+        self.assertListEqual(response_data['objects']['results'],
+                             [self.serialize_course_run(course_run), self.serialize_program(program)])