Merge pull request #2962 from aptivate/override-feed-class

Allow RSS feed to be extended

ckan/controllers/feed.py

@@ -31,6 +31,7 @@
 import ckan.lib.base as base
 import ckan.lib.helpers as h
 import ckan.logic as logic
+import ckan.plugins as plugins
 
 from ckan.common import _, g, c, request, response, json
 
@@ -361,10 +362,18 @@ def output_feed(self, results, feed_title, feed_description,
             config.get('ckan.site_url', '').strip()
 
         # TODO language
-        feed = _FixedAtom1Feed(
-            title=feed_title,
-            link=feed_link,
-            description=feed_description,
+        feed_class = None
+        for plugin in plugins.PluginImplementations(plugins.IFeed):
+            if hasattr(plugin, 'get_feed_class'):
+                feed_class = plugin.get_feed_class()
+
+        if not feed_class:
+            feed_class = _FixedAtom1Feed
+
+        feed = feed_class(
+            feed_title,
+            feed_link,
+            feed_description,
             language=u'en',
             author_name=author_name,
             author_link=author_link,
@@ -377,6 +386,12 @@ def output_feed(self, results, feed_title, feed_description,
         )
 
         for pkg in results:
+            additional_fields = {}
+
+            for plugin in plugins.PluginImplementations(plugins.IFeed):
+                if hasattr(plugin, 'get_item_additional_fields'):
+                    additional_fields = plugin.get_item_additional_fields(pkg)
+
             feed.add_item(
                 title=pkg.get('title', ''),
                 link=self.base_url + h.url_for(controller='package',
@@ -396,7 +411,8 @@ def output_feed(self, results, feed_title, feed_description,
                                               id=pkg['name'],
                                               ver='2'),
                     unicode(len(json.dumps(pkg))),   # TODO fix this
-                    u'application/json')
+                    u'application/json'),
+                **additional_fields
             )
         response.content_type = feed.mime_type
         return feed.writeString('utf-8')

ckan/plugins/interfaces.py

@@ -12,6 +12,7 @@
     u'IMiddleware',
     u'IAuthFunctions',
     u'IDomainObjectModification',
+    u'IFeed',
     u'IGroupController',
     u'IOrganizationController',
     u'IPackageController',
@@ -206,6 +207,51 @@ def notify_after_commit(self, entity, operation):
         pass
 
 
+class IFeed(Interface):
+    """
+    Allows extension of the default Atom feeds
+    """
+
+    def get_feed_class(self):
+        """
+        Allows plugins to provide a custom class to generate feed items.
+
+        :returns: feed class
+        :rtype: type
+
+        The feed item generator's constructor is called as follows::
+
+            feed_class(
+                feed_title,        # Mandatory
+                feed_link,         # Mandatory
+                feed_description,  # Mandatory
+                language,          # Optional, always set to 'en'
+                author_name,       # Optional
+                author_link,       # Optional
+                feed_guid,         # Optional
+                feed_url,          # Optional
+                previous_page,     # Optional, url of previous page of feed
+                next_page,         # Optional, url of next page of feed
+                first_page,        # Optional, url of first page of feed
+                last_page,         # Optional, url of last page of feed
+            )
+
+        """
+
+        pass
+
+    def get_item_additional_fields(self, dataset_dict):
+        """
+        Allows plugins to set additional fields on a feed item.
+
+        :param dataset_dict: the dataset metadata
+        :type dataset_dict: dictionary
+        :returns: the fields to set
+        :rtype: dictionary
+        """
+        pass
+
+
 class IResourceUrlChange(Interface):
     u'''
     Receives notification of changed urls.

ckan/tests/controllers/test_feed.py

@@ -1,6 +1,9 @@
 # encoding: utf-8
 
 from routes import url_for
+from webhelpers.feedgenerator import GeoAtom1Feed
+
+import ckan.plugins as plugins
 
 import ckan.tests.helpers as helpers
 import ckan.tests.factories as factories
@@ -81,3 +84,58 @@ def test_custom_atom_feed_works(self):
         assert '<title>{0}</title>'.format(dataset1['title']) in res.body
 
         assert '<title>{0}</title>'.format(dataset2['title']) not in res.body
+
+
+class TestFeedInterface(helpers.FunctionalTestBase):
+    @classmethod
+    def setup_class(cls):
+        super(TestFeedInterface, cls).setup_class()
+
+        if not plugins.plugin_loaded('test_feed_plugin'):
+            plugins.load('test_feed_plugin')
+
+    @classmethod
+    def teardown_class(cls):
+        helpers.reset_db()
+        plugins.unload('test_feed_plugin')
+
+    def test_custom_class_used(self):
+        offset = url_for(controller='feed', action='general')
+        app = self._get_test_app()
+        res = app.get(offset)
+
+        assert 'xmlns:georss="http://www.georss.org/georss"' in res.body, res.body
+
+    def test_additional_fields_added(self):
+        metadata = {
+            'ymin': '-2373790',
+            'xmin': '2937940',
+            'ymax': '-1681290',
+            'xmax': '3567770',
+        }
+
+        extras = [
+            {'key': k, 'value': v} for (k, v) in
+            metadata.items()
+        ]
+
+        factories.Dataset(extras=extras)
+        offset = url_for(controller='feed', action='general')
+        app = self._get_test_app()
+        res = app.get(offset)
+
+        assert '<georss:box>-2373790.000000 2937940.000000 -1681290.000000 3567770.000000</georss:box>' in res.body, res.body
+
+
+class MockFeedPlugin(plugins.SingletonPlugin):
+    plugins.implements(plugins.IFeed)
+
+    def get_feed_class(self):
+        return GeoAtom1Feed
+
+    def get_item_additional_fields(self, dataset_dict):
+        extras = {e['key']: e['value'] for e in dataset_dict['extras']}
+
+        box = tuple(float(extras.get(n))
+                    for n in ('ymin', 'xmin', 'ymax', 'xmax'))
+        return {'geometry': box}

setup.py

@@ -166,6 +166,7 @@
         'test_datapusher_plugin = ckanext.datapusher.tests.test_interfaces:FakeDataPusherPlugin',
         'test_routing_plugin = ckan.tests.config.test_middleware:MockRoutingPlugin',
         'test_helpers_plugin = ckan.tests.lib.test_helpers:TestHelpersPlugin',
+        'test_feed_plugin = ckan.tests.controllers.test_feed:MockFeedPlugin',
     ],
     'babel.extractors': [
         'ckan = ckan.lib.extract:extract_ckan',