refactor: make QueryFilterFactory return a list of filters #259

- This is in preparation to add a `SearchAPIQueryFilterFactory` where a single query parameter will have multiple filters
- This commit also fixes the tests which impact this change

datagateway_api/common/datagateway_api/query_filter_factory.py

@@ -57,18 +57,18 @@ def get_query_filter(request_filter):
             field = list(request_filter[filter_name].keys())[0]
             operation = list(request_filter[filter_name][field].keys())[0]
             value = request_filter[filter_name][field][operation]
-            return WhereFilter(field, value, operation)
+            return [WhereFilter(field, value, operation)]
         elif filter_name == "order":
             field = request_filter["order"].split(" ")[0]
             direction = request_filter["order"].split(" ")[1]
-            return OrderFilter(field, direction)
+            return [OrderFilter(field, direction)]
         elif filter_name == "skip":
-            return SkipFilter(request_filter["skip"])
+            return [SkipFilter(request_filter["skip"])]
         elif filter_name == "limit":
-            return LimitFilter(request_filter["limit"])
+            return [LimitFilter(request_filter["limit"])]
         elif filter_name == "include":
-            return IncludeFilter(request_filter["include"])
+            return [IncludeFilter(request_filter["include"])]
         elif filter_name == "distinct":
-            return DistinctFieldFilter(request_filter["distinct"])
+            return [DistinctFieldFilter(request_filter["distinct"])]
         else:
             raise FilterError(f" Bad filter: {request_filter}")

datagateway_api/common/helpers.py

@@ -103,7 +103,7 @@ def get_filters_from_query_string():
         filters = []
         for arg in request.args:
             for value in request.args.getlist(arg):
-                filters.append(
+                filters.extend(
                     QueryFilterFactory.get_query_filter({arg: json.loads(value)}),
                 )
         return filters

test/db/test_query_filter_factory.py

@@ -13,13 +13,13 @@
 )
 
 
+# TODO - Move outside of db/
 class TestQueryFilterFactory:
     @pytest.mark.usefixtures("flask_test_app_db")
     def test_valid_distinct_filter(self):
-        assert isinstance(
-            QueryFilterFactory.get_query_filter({"distinct": "TEST"}),
-            DatabaseDistinctFieldFilter,
-        )
+        test_filter = QueryFilterFactory.get_query_filter({"distinct": "TEST"})
+        assert isinstance(test_filter[0], DatabaseDistinctFieldFilter)
+        assert len(test_filter) == 1
 
     @pytest.mark.usefixtures("flask_test_app_db")
     @pytest.mark.parametrize(
@@ -34,28 +34,27 @@ def test_valid_distinct_filter(self):
         ],
     )
     def test_valid_include_filter(self, filter_input):
-        assert isinstance(
-            QueryFilterFactory.get_query_filter(filter_input), DatabaseIncludeFilter,
-        )
+        test_filter = QueryFilterFactory.get_query_filter(filter_input)
+        assert isinstance(test_filter[0], DatabaseIncludeFilter)
+        assert len(test_filter) == 1
 
     @pytest.mark.usefixtures("flask_test_app_db")
     def test_valid_limit_filter(self):
-        assert isinstance(
-            QueryFilterFactory.get_query_filter({"limit": 10}), DatabaseLimitFilter,
-        )
+        test_filter = QueryFilterFactory.get_query_filter({"limit": 10})
+        assert isinstance(test_filter[0], DatabaseLimitFilter)
+        assert len(test_filter) == 1
 
     @pytest.mark.usefixtures("flask_test_app_db")
     def test_valid_order_filter(self):
-        assert isinstance(
-            QueryFilterFactory.get_query_filter({"order": "id DESC"}),
-            DatabaseOrderFilter,
-        )
+        test_filter = QueryFilterFactory.get_query_filter({"order": "id DESC"})
+        assert isinstance(test_filter[0], DatabaseOrderFilter)
+        assert len(test_filter) == 1
 
     @pytest.mark.usefixtures("flask_test_app_db")
     def test_valid_skip_filter(self):
-        assert isinstance(
-            QueryFilterFactory.get_query_filter({"skip": 10}), DatabaseSkipFilter,
-        )
+        test_filter = QueryFilterFactory.get_query_filter({"skip": 10})
+        assert isinstance(test_filter[0], DatabaseSkipFilter)
+        assert len(test_filter) == 1
 
     @pytest.mark.usefixtures("flask_test_app_db")
     @pytest.mark.parametrize(
@@ -72,6 +71,6 @@ def test_valid_skip_filter(self):
         ],
     )
     def test_valid_where_filter(self, filter_input):
-        assert isinstance(
-            QueryFilterFactory.get_query_filter(filter_input), DatabaseWhereFilter,
-        )
+        test_filter = QueryFilterFactory.get_query_filter(filter_input)
+        assert isinstance(test_filter[0], DatabaseWhereFilter)
+        assert len(test_filter) == 1