add support to excludes and filters results based upon query params (#15)

Author: manjitkumar

docs/README.md

@@ -90,22 +90,23 @@ class PlayersViewSet(FiltersMixin, viewsets.ModelViewSet):
         query parameters in the URL.
         """
         query_params = self.request.query_params
-        queryset = Player.objects.prefetch_related(
-            'teams'  # use prefetch_related to minimize db hits.
-        ).all()
+        url_params = self.kwargs
+
+        # get queryset_filters from FilterMixin
+        queryset_filters = self.get_db_filters(url_params, query_params)
 
         # This dict will hold filter kwargs to pass in to Django ORM calls.
-        db_filters = {}
+        db_filters = queryset_filters['db_filters']
 
-        # update filters dict with incoming query params and then pass as
-        # **kwargs to queryset.filter()
-        db_filters.update(
-            self.get_queryset_filters(
-                query_params
-            )
-        )
-        return queryset.filter(**db_filters)
+        # This dict will hold exclude kwargs to pass in to Django ORM calls.
+        db_excludes = queryset_filters['db_excludes']
+
+        # fetch queryset from Players model
+        queryset = Player.objects.prefetch_related(
+            'teams'  # use prefetch_related to minimize db hits.
+        ).all()
 
+        return queryset.filter(**db_filters).exclude(**db_excludes)
 ```
 
 With the use of `drf-url-filters` adding a new filter on a new column is as simple as adding a new key in the dict. Prohibitting a filter on particular column is same as removing a key value mapping from the `filter_mappings` dict.
@@ -117,7 +118,7 @@ Copyright (c) 2016 Manjit Kumar
 Read more about it in LICENSE file available in repo.
 
 # Credits
-Special thanks to authors of [voluptouos](https://github.com/alecthomas/voluptuous) and friends [*](https://github.com/cdax) [**](https://github.com/SaurabhJha) who encourage people to contribute into open source community.
+Special thanks to authors of [voluptouos](https://github.com/alecthomas/voluptuous) and friends [saurabhjha](https://github.com/cdax) [cdax](https://github.com/SaurabhJha) who encourage people to contribute into open source community.
 
 # Support
 Please [open an issue](https://github.com/manjitkumar/drf-url-filters/issues/new) for support.

example_app/views.py

@@ -43,21 +43,23 @@ def get_queryset(self):
         query parameters in the URL.
         """
         query_params = self.request.query_params
+        url_params = self.kwargs
+
+        # get queryset_filters from FilterMixin
+        queryset_filters = self.get_db_filters(url_params, query_params)
+
+        # This dict will hold filter kwargs to pass in to Django ORM calls.
+        db_filters = queryset_filters['db_filters']
+
+        # This dict will hold exclude kwargs to pass in to Django ORM calls.
+        db_excludes = queryset_filters['db_excludes']
+
+        # fetch queryset from Players model
         queryset = Player.objects.prefetch_related(
             'teams'  # use prefetch_related to minimize db hits.
         ).all()
 
-        # This dict will hold filter kwargs to pass in to Django ORM calls.
-        db_filters = {}
-
-        # update filters dict with incoming query params and then pass as
-        # **kwargs to queryset.filter()
-        db_filters.update(
-            self.get_queryset_filters(
-                query_params
-            )
-        )
-        return queryset.filter(**db_filters)
+        return queryset.filter(**db_filters).exclude(**db_excludes)
 
 
 class TeamsViewSet(FiltersMixin, viewsets.ModelViewSet):
@@ -90,18 +92,21 @@ def get_queryset(self):
         Optionally restricts the queryset by filtering against
         query parameters in the URL.
         """
+
         query_params = self.request.query_params
+        url_params = self.kwargs
+
+        # get queryset_filters from FilterMixin
+        queryset_filters = self.get_db_filters(url_params, query_params)
+
+        # This dict will hold filter kwargs to pass in to Django ORM calls.
+        db_filters = queryset_filters['db_filters']
+
+        # This dict will hold exclude kwargs to pass in to Django ORM calls.
+        db_excludes = queryset_filters['db_excludes']
+
         queryset = Team.objects.prefetch_related(
             'players'
         ).all()
 
-        # This dict will hold filter kwargs to pass in to Django ORM calls.
-        db_filters = {}
-
-        # filters on mercant queryset
-        db_filters.update(
-            self.get_queryset_filters(
-                query_params
-            )
-        )
-        return queryset.filter(**db_filters)
+        return queryset.filter(**db_filters).exclude(**db_excludes)

filters/mixins.py

@@ -9,38 +9,72 @@ class FiltersMixin(object):
     queryset.
     '''
 
-    def get_queryset_filters(self, query_params, *args, **kwargs):
+    def __get_queryset_filters(self, query_params, *args, **kwargs):
         '''
         get url_params and query_params and make db_filters
         to filter the queryset to the finest.
-
-        [1] when a CSV is passed as value to a query params make a filter
+        [1] ~ sign is used to negated / exclude a filter.
+        [2] when a CSV is passed as value to a query params make a filter
             with 'IN' query.
         '''
 
         filters = []
+        excludes = []
+
         if getattr(self, 'filter_mappings', None) and query_params:
             filter_mappings = self.filter_mappings
 
             try:
                 # check and raise 400_BAD_REQUEST for invalid query params
-                if getattr(self, 'filter_validation_schema', None):
-                    query_params = self.filter_validation_schema(
-                        self.request.query_params
-                    )
-                else:
-                    raise Invalid('Validation is not configured for filters.')
+                filter_validation_schema = getattr(
+                    self,
+                    'filter_validation_schema',
+                    base_query_params_schema
+                )
+                query_params = filter_validation_schema(query_params)
             except Invalid as inst:
                 raise ParseError(detail=inst)
 
-            filters = []
-            for query, value in query_params.items():
+            for query, value in query_params.iteritems():
+                # [1] ~ sign is used to exclude a filter.
+                is_exclude = '~' in query
                 if query in self.filter_mappings and value:
                     query = filter_mappings[query]
-                    # [1] multiple options is filter values will execute as in query
+                    # [2] multiple options is filter values will execute as `IN` query
                     if isinstance(value, list):
                         query += '__in'
                     if value:
-                        filters.append((query, value))
-            filters = dict(filters)
-        return filters
+                        if is_exclude:
+                            excludes.append((query, value))
+                        else:
+                            filters.append((query, value))
+
+        return dict(filters), dict(excludes)
+
+    def __merge_query_params(url_params, query_params):
+        '''
+        merges the url_params dict with query_params query dict and returns
+        the merged dict.
+        '''
+        url_params = {}
+        for key in query_params:
+            url_params[key] = query_params.get(key) # get method on query-dict works differently than on dict.
+        return url_params
+
+    def get_db_filters(self, url_params, query_params):
+        '''
+        returns a dict with db_filters and db_excludes values which can be
+        used to apply on viewsets querysets.
+        '''
+
+        # merge url and query params
+        query_params = self.__merge_query_params(url_params, query_params)
+
+        # get queryset filters
+        db_filters = self.__get_queryset_filters(query_params)[0]
+        db_excludes = self.__get_queryset_filters(query_params)[1]
+
+        return {
+            'db_filters': db_filters,
+            'db_excludes': db_excludes,
+        }

setup.py

@@ -19,7 +19,7 @@
 os.chdir(os.path.normpath(os.path.join(os.path.abspath(__file__), os.pardir)))
 
 __name__ = 'drf-url-filters'
-__version__ = '0.1.4'
+__version__ = '0.2.0'
 __author__ = 'Manjit Kumar'
 __author_email__ = 'manjit1727@gmail.com'
 __url__ = 'https://github.com/manjitkumar/drf-url-filters'