Storing hierarchical (parent/child) data in Python/Django: MPTT alternative?

Question

I'm looking for a good way to store and use hierarchical (parent/child) data in Django. I've been using django-mptt, but it seems entirely incompatible with my brain - I end up with non-obvious bugs in non-obvious places, mostly when moving things around in the tree: I end up with inconsistent state, where a node and its parent will disagree on their relationship.

My needs are simple:

• Given a node:
  • find its root
  • find its ancestors
  • find its descendants
• With a tree:
  • easily move nodes (ie. change parent)

My trees will be smallish (at most 10k nodes over 20 levels, generally much much smaller, say 10 nodes with 1 or 2 levels).

I have to think there has to be an easier way to do trees in python/django. Are there other approaches that do a better job of maintaining consistency?

Noenoel

django-mptt is great - just read some of Daniel Roseman's answer here (#2325227) for some help with moving nodes around. Don't give up! – Jase

Thanks, that looks like the likely cause of my issues as well, but I don't trust myself to get that right every time - seems too easy to miss. I'll echo your comment: "Still a bit nervous about MPTT and the possibility of the tree getting into a bad state" :-) I take it you ended up happy? – Noenoel

Answer 1

django-treebeard is another option. It has great documentation. I believe it meets all of your above requirements and includes some functions for checking the tree for problems and fixing those problems in the tree.

Node.find_problems() https://tabo.pe/projects/django-treebeard/docs/1.60/api.html#treebeard.models.Node.find_problems

Node.fix_tree() https://tabo.pe/projects/django-treebeard/docs/1.60/api.html#treebeard.models.Node.fix_tree

Enigmatic

For what it's worth I ended up sticking with mptt and working through the issues, although I'm not particularly happy about it. treebeard looks like a good alternative so I'm accepting the answer. – Noenoel