[ckan-dev] Activity streams issue with deleted objects

Sun Feb 5 19:33:17 UTC 2012

Hey, I just wanted to flag up this issue I'm having with the activity 
streams:

http://trac.ckan.org/ticket/1743

If you delete an object such as a dataset, previous activity stream 
activities such as "Alice updated the dataset Foo" etc. still hyperlink 
to the deleted dataset. If it's a dataset for example the link takes you 
to a page where you can still see the 'deleted' dataset. If it's a 
resource the link might take you to a 404.

I'm not sure how important this is or how to fix it.

I think the activity streams logic action functions such as 
user_activity_list() etc. are probably the right place to fix this. The 
function gets a list of Activity objects from the database, and each 
Activity object holds the ID of the object of the activity (the Package 
or Resource etc.) But the object which the ID identifies could be of 
several types (Package, Resource...) so you can't simply do something 
like model.Package.get(id) to find out if the object still exists. You 
would have to switch on the activity_type field of the Activity object, 
like:

     if activity.activity_type in ('new package', 'changed package', 
'deleted package'):
         obj = model.Package.get(id)
     elif activity.activity_type in ('new resource', 'changed resource', 
'deleted resource'):
         obj = model.Resource.get(id)
     elif ...:
         ...

This doesn't seem like a very good solution.

The only other thing I can think of so far is to look for the most 
recent activity in the activities table for that object ID and see if 
the state of the object at the time of that activity (recorded in the 
activities table row) was 'deleted'.

Is there a better way around this?