[entities] Do not push already pushed resources

Look for existing resources on CKAN side and compare with their url (download
url).

entities.py

@@ -64,6 +64,14 @@ class CKANPublishableAdapter(EntityAdapter):
         # XXX CKAN uses Markdown syntax for notes field.
         return self.entity.printable_value('description', format='text/plain')
 
+    def ckan_package_resources(self):
+        """Return the list of resources URL for dataset"""
+        data = {'id': self.entity.ckan_dataset_id}
+        res = ckan_post(self._cw.vreg.config, 'package_show', data)
+        if res:
+            return [d['url'] for d in res['resources']]
+        return []
+
     def ckan_get_organization_id(self, orgname):
         """Retrieve the ID of an organization given its name"""
         data = {'organizations': [orgname],
@@ -122,6 +130,7 @@ class CKANPublishableAdapter(EntityAdapter):
 
     def ckan_resources(self):
         """Yield dicts of CKAN dataset resource info"""
+        resources_url = self.ckan_package_resources()
         for entity in self.dataset_resources():
             adapted = entity.cw_adapt_to('IDownloadable')
             if adapted is None:
@@ -129,7 +138,12 @@ class CKANPublishableAdapter(EntityAdapter):
                     'invalid resource %r, could not adapt to IDownloadable',
                     entity)
                 continue
-            yield {'url': adapted.download_url(),
+            url = adapted.download_url()
+            if url in resources_url:
+                self.info('skipping resource %s and it seems to be already '
+                          'on CKAN side', entity)
+                continue
+            yield {'url': url,
                    'name': adapted.download_file_name(),
                    'mimetype': adapted.download_content_type(),
                    'created': str(entity.creation_date),

test/unittest_hooks.py

@@ -89,6 +89,14 @@ class CKANPublishHooksTC(CubicWebTC):
         r0 = resources[0]
         iresource = resource.cw_adapt_to('IDownloadable')
         self.assertEqual(r0['url'], iresource.download_url())
+        # Update the entity (should trigger another push to CKAN, but no new
+        # resource).
+        entity.cw_set(description=u'blurp')
+        cnx.commit()
+        result = ckan_post(self.ckan_config, 'package_show',
+                           {'id': entity.ckan_dataset_id})
+        resources = result['resources']
+        self.assertEqual(len(resources), 1)
 
     def _check_entity_delete(self, cnx, entity):
         self.set_description('entity deletion')