django-mptt

========================================== This project is currently unmaintained

Alternatives to django-mptt include:

• django-treebeard <https://pypi.org/project/django-treebeard/>_ includes a MPTT implementation (called a nested set), but the state of maintenance is unclear.
• Maybe you do not need MPTT, especially when using newer databases. See django-tree-queries <https://github.com/matthiask/django-tree-queries>_ for an implementation using recursive Common Table Expressions (CTE). See the announcement blog post <https://406.ch/writing/django-tree-queries/>__.

=========== django-mptt

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

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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_

.. _Trees in SQL: https://www.ibase.ru/files/articles/programming/dbmstrees/sqltrees.html .. _Storing Hierarchical Data in a Database: https://www.sitepoint.com/hierarchical-data-database/ .. _Managing Hierarchical Data in MySQL: http://mikehillyer.com/articles/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.

.. _Form fields: https://django-mptt.readthedocs.io/en/latest/forms.html .. _Utility functions: https://django-mptt.readthedocs.io/en/latest/utilities.html .. _Template tags and filters: https://django-mptt.readthedocs.io/en/latest/templates.html .. _Admin classes: https://django-mptt.readthedocs.io/en/latest/admin.html