Fix dataset-purge Paster command

The dataset-purge command leaves dangling references to purged datasets in "member"
table (so this fix takes care to remove those membership records before).

ckan/lib/cli.py

@@ -18,6 +18,7 @@
 import paste.script
 from paste.registry import Registry
 from paste.script.util.logging_config import fileConfig
+from sqlalchemy import or_, and_
 
 #NB No CKAN imports are allowed until after the config file is loaded.
 #   i.e. do the imports in methods, after _load_config is called.
@@ -925,7 +926,16 @@ def purge(self, dataset_ref):
         name = dataset.name
 
         rev = model.repo.new_revision()
+
+        # Purge membership to several groups
+        q_member = model.Session.query(model.Member).filter(and_(
+            model.Member.table_name == 'package',
+            model.Member.table_id == dataset_ref))
+        for memb in q_member.all():
+            memb.purge()
+        # Purge actual dataset
         dataset.purge()
+
         model.repo.commit_and_remove()
         print '%s purged' % name
 

ckan/model/group.py

@@ -102,13 +102,14 @@ def related_packages(self):
             id=self.table_id).all()
 
     def __unicode__(self):
-        # refer to objects by name, not ID, to help debugging
+        # Try to refer to objects by name, not ID, to help debugging
+        # Note A referenced object may be already deleted into the same transaction 
         if self.table_name == 'package':
-            table_info = 'package=%s' % meta.Session.query(_package.Package).\
-                get(self.table_id).name
+            pkg = meta.Session.query(_package.Package).get(self.table_id)
+            table_info = 'package=%s' % (pkg.name if pkg else self.table_id)
         elif self.table_name == 'group':
-            table_info = 'group=%s' % meta.Session.query(Group).\
-                get(self.table_id).name
+            grp = meta.Session.query(Group).get(self.table_id)
+            table_info = 'group=%s' % (grp.name if grp else self.table_id)
         else:
             table_info = 'table_name=%s table_id=%s' % (self.table_name,
                                                         self.table_id)