On Jul 11, 11:37 am, "Daniele Procida" <dani...@apple-juice.co.uk> wrote: > I have a many-to-many relationship between two models, People and > Entities (enities are departments and offices etc). > > Some of these relationships are managed by the user in admin, but others > are implicit. > > For example, if the user adds John to the Laser Research Lab > Administrative Office, it means that John is also a member of the Laser > Research Lab. This is because the Entities are in a hierarchy, and being > a member of one means being a member of its parent. > > Because there will be thousands of people and hundreds of entities, I > can see that my present functions to find out what members an entity > has, or what entities someone is a member of, will involve lots of looping. > > I would rather assemble this information only when the user makes a > change to the admin, and for each person have a list of entities that > can quickly be read off, and vice-versa for the entities. > > I think this means that I need to add a routine to my admin.py so that > when the user hits Save, it will also manually assemble the information > and save it for the affected models. > > Is that correct? If so, what is doing this called, so I can look it up > in the documentation? > > Thanks, > > Daniele
Well, this is called a Signal, and you wouldn't do it in admin.py necessarily - you would connect a function to the post-save signal so that any time the user is saved, the group information is also collected and saved. However I think a better solution for you would be to investigate django-mptt. MPTT is an algorithm that allows you to efficiently retrieve hierarchical data, so that in your example you would be able to get the user's group and all of its parent groups in a single query rather than having to denormalise the data and store it per user. -- DR. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
