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

Utilities for implementing a modified pre-order traversal tree in django.
https://github.com/django-mptt/django-mptt

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Utilities for implementing a modified pre-order traversal tree in django.

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README 

        
==========================================

**This project is currently unmaintained**

==========================================



You can find alternatives to django-mptt on

`Django Packages `__. 

Maybe you do not need MPTT, especially when using newer databases. See

`django-tree-queries `_ for an

implementation using recursive Common Table Expressions (CTE). Here's its

`announcement blog post `__.



===========

django-mptt

===========



Utilities for implementing Modified Preorder Tree Traversal with your

Django Models and working with trees of Model instances.



.. image:: https://secure.travis-ci.org/django-mptt/django-mptt.svg?branch=master

    :alt: Build Status

    :target: https://travis-ci.org/django-mptt/django-mptt



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