This project is currently unmaintained

django-mptt works by storing pre-computed left/right/level/tree_id values alongside each row. This makes reads very fast, but it means that every insert, move, or delete must update a potentially large number of sibling and ancestor rows. This write amplification is the fundamental reason the library is hard to maintain: concurrent writes can race and corrupt the tree, bulk operations bypass the update logic entirely, and any code that touches the database outside of django-mptt (raw SQL, bulk_update, migrations) can leave the tree in an inconsistent state. Rebuilding with rebuild() is the escape hatch, but it locks the table.

If you are starting a new project, or can afford to migrate, consider an alternative. Newer databases support recursive Common Table Expressions (CTE), which let you store only a parent FK and compute ancestry on the fly. See django-tree-queries for such an implementation and its announcement blog post. Other alternatives are listed on Django Packages.

django-mptt itself is kept alive on a best-effort basis — bugs get fixed when reported with a clear reproduction, compatibility with new Django versions is maintained, but new features will not be added.

Utilities for implementing Modified Preorder Tree Traversal with your Django Models and working with trees of Model instances.

Project home: https://github.com/django-mptt/django-mptt/

Documentation: https://django-mptt.readthedocs.io/

Discussion group: https://groups.google.com/forum/#!forum/django-mptt-dev

What is Modified Preorder Tree Traversal?

MPTT is a technique for storing hierarchical data in a database. The aim is to make retrieval operations very efficient.

The trade-off for this efficiency is that performing inserts and moving items around the tree are more involved, as there's some extra work required to keep the tree structure in a good state at all times.

Here are a few articles about MPTT to whet your appetite and provide details about how the technique itself works:

• Trees in SQL
• Storing Hierarchical Data in a Database
• Managing Hierarchical Data in MySQL

What is django-mptt?

django-mptt is a reusable Django app that aims to make it easy for you to use MPTT with your own Django models.

It takes care of the details of managing a database table as a tree structure and provides tools for working with trees of model instances.

Requirements

• A supported version of Python: https://devguide.python.org/versions/#supported-versions
• A supported version of Django: https://www.djangoproject.com/download/#supported-versions

Feature overview

• Simple registration of models - fields required for tree structure will be added automatically.
• The tree structure is automatically updated when you create or delete model instances, or change an instance's parent.
• Each level of the tree is automatically sorted by a field (or fields) of your choice.
• New model methods are added to each registered model for:
  • changing position in the tree
  • retrieving ancestors, siblings, descendants
  • counting descendants
  • other tree-related operations
• A TreeManager manager is added to all registered models. This provides methods to:
  • move nodes around a tree, or into a different tree
  • insert a node anywhere in a tree
  • rebuild the MPTT fields for the tree (useful when you do bulk updates outside of Django)
• Form fields for tree models.
• Utility functions for tree models.
• Template tags and filters for rendering trees.
• Admin classes for visualizing and modifying trees in Django's administration interface.