On 01/28/2010 11:12 AM, Matthias Kestenholz wrote: > Hi > > On Wed, Jan 27, 2010 at 11:29 PM, Olivier Guilyardi <m...@xung.org> wrote: >> Hi, >> >> I'm working with a polyhierarchical thesaurus, and trying to handle that in >> Django. By polyhierarchical, I mean : nodes can have both multiple parents >> and >> children. >> >> Actually, this is a geographical thesaurus, and yes a location can have >> multiple >> parents (being across countries, etc..). >> >> I have read about the Nested set paradigm [1], and would love to use that, >> maybe >> through django-mptt or django-treebeard. But unless someone shows me how, >> nested >> sets aren't suitable for polyhierarchical data. >> >> Currently I have a simple recursive many-to-many mapping. This allows to >> establish the poly-relations, but is completely unusable for real use cases. >> >> For instance, I have a table of "items", with a "location" field which >> points to >> a location in the thesaurus. >> >> Now I need to list all items which are located in a given country. >> >> I just can't filter by country, there's no such field in the items table. >> And a >> location can be of any level of precision, such as country, region, city, >> village, etc.. >> >> The nested set would be perfect for this, but apparently can't handle >> multiple >> parents. >> >> Do you see a fast and elegant way to handle this ? >> >> [1] http://dev.mysql.com/tech-resources/articles/hierarchical-data.html >> > > Maybe you could take a look at this project? > http://bitbucket.org/cmutel/django-directed-acyclic-graph/
It's quite interesting indeed. However, it uses database stored functions and triggers, which isn't very portable. What's great about the Nested set solution is that it can be achieved through standard Django model api calls. Unfortunately it doesn't fit the job. I'm still looking for an elegant solution, that I'll hopefully find soon... Thanks -- Olivier -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-us...@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.
