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sqlalchemy_mptt

SQLAlchemy nested sets mixin (MPTT)

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Library for implementing Modified Preorder Tree Traversal with your SQLAlchemy Models and working with trees of Model instances, like django-mptt. Docs http://sqlalchemy-mptt.readthedocs.io/

.. image:: https://cdn.rawgit.com/uralbash/sqlalchemy_mptt/master/docs/img/2_sqlalchemy_mptt_traversal.svg :alt: Nested sets traversal :width: 800px

The nested set model is a particular technique for representing nested sets (also known as trees or hierarchies) in relational databases.

Installing

Install from github:

.. code-block:: bash

pip install git+http://github.com/uralbash/sqlalchemy_mptt.git

PyPi:

.. code-block:: bash

pip install sqlalchemy_mptt

Source:

.. code-block:: bash

pip install -e .

Usage

Add mixin to model

.. code-block:: python

from sqlalchemy import Column, Integer, Boolean
from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy_mptt.mixins import BaseNestedSets

Base = declarative_base()


class Tree(Base, BaseNestedSets):
    __tablename__ = "tree"

    id = Column(Integer, primary_key=True)
    visible = Column(Boolean)

    def __repr__(self):
        return "<Node (%s)>" % self.id

Now you can add, move and delete obj!

Insert node

.. code-block:: python

node = Tree(parent_id=6)
session.add(node)

::

        level           Nested sets example
        1                    1(1)22
                _______________|___________________
               |               |                   |
        2    2(2)5           6(4)11             12(7)21
               |               ^                   ^
        3    3(3)4       7(5)8   9(6)10    13(8)16   17(10)20
                                              |          |
        4                                  14(9)15   18(11)19

        level     Insert node with parent_id == 6
        1                    1(1)24
                _______________|_________________
               |               |                 |
        2    2(2)5           6(4)13           14(7)23
               |           ____|____          ___|____
               |          |         |        |        |
        3    3(3)4      7(5)8    9(6)12  15(8)18   19(10)22
                                   |        |         |
        4                      10(23)11  16(9)17  20(11)21

Delete node

.. code:: python

node = session.query(Tree).filter(Tree.id == 4).one()
session.delete(node)

::

        level           Nested sets example
        1                    1(1)22
                _______________|___________________
               |               |                   |
        2    2(2)5           6(4)11             12(7)21
               |               ^                   ^
        3    3(3)4       7(5)8   9(6)10    13(8)16   17(10)20
                                              |          |
        4                                  14(9)15   18(11)19

        level         Delete node == 4
        1                    1(1)16
                _______________|_____
               |                     |
        2    2(2)5                 6(7)15
               |                     ^
        3    3(3)4            7(8)10   11(10)14
                                |          |
        4                     8(9)9    12(11)13

Update node

.. code:: python

node = session.query(Tree).filter(Tree.id == 8).one()
node.parent_id = 5
session.add(node)

::

        level           Nested sets example
            1                    1(1)22
                    _______________|___________________
                   |               |                   |
            2    2(2)5           6(4)11             12(7)21
                   |               ^                   ^
            3    3(3)4       7(5)8   9(6)10    13(8)16   17(10)20
                                                  |          |
            4                                  14(9)15   18(11)19

        level               Move 8 - > 5
            1                     1(1)22
                     _______________|__________________
                    |               |                  |
            2     2(2)5           6(4)15            16(7)21
                    |               ^                  |
            3     3(3)4      7(5)12   13(6)14      17(10)20
                               |                        |
            4                8(8)11                18(11)19
                               |
            5                9(9)10

Move node (support multitree)

.. figure:: https://cdn.rawgit.com/uralbash/sqlalchemy_mptt/master/docs/img/3_sqlalchemy_mptt_multitree.svg :alt: Nested sets multitree :width: 600px

Nested sets multitree

Move inside

.. code:: python

node = session.query(Tree).filter(Tree.id == 4).one()
node.move_inside("15")

::

                 4 -> 15
        level           Nested sets tree1
        1                    1(1)16
                _______________|_____________________
               |                                     |
        2    2(2)5                                 6(7)15
               |                                     ^
        3    3(3)4                            7(8)10   11(10)14
                                                |          |
        4                                     8(9)9    12(11)13

        level           Nested sets tree2
        1                     1(12)28
                 ________________|_______________________
                |                |                       |
        2    2(13)5            6(15)17                18(18)27
               |                 ^                        ^
        3    3(14)4    7(4)12 13(16)14  15(17)16  19(19)22  23(21)26
                         ^                            |         |
        4          8(5)9  10(6)11                 20(20)21  24(22)25

Move after

.. code:: python

node = session.query(Tree).filter(Tree.id == 8).one()
node.move_after("5")

::

       level           Nested sets example
            1                    1(1)22
                    _______________|___________________
                   |               |                   |
            2    2(2)5           6(4)11             12(7)21
                   |               ^                   ^
            3    3(3)4       7(5)8   9(6)10    13(8)16   17(10)20
                                                  |          |
            4                                  14(9)15   18(11)19

        level               Move 8 after 5
            1                     1(1)22
                     _______________|__________________
                    |               |                  |
            2     2(2)5           6(4)15            16(7)21
                    |               ^                  |
            3     3(3)4    7(5)8  9(8)12  13(6)14   17(10)20
                                    |                  |
            4                    10(9)11            18(11)19

Move to top level

.. code:: python

node = session.query(Tree).filter(Tree.id == 15).one()
node.move_after("1")

::

        level           tree_id = 1
        1                    1(1)22
                _______________|___________________
               |               |                   |
        2    2(2)5           6(4)11             12(7)21
               |               ^                   ^
        3    3(3)4       7(5)8   9(6)10    13(8)16   17(10)20
                                              |          |
        4                                  14(9)15   18(11)19

        level           tree_id = 2
        1                     1(15)6
                                 ^
        2                 2(16)3   4(17)5

        level           tree_id = 3
        1                    1(12)16
                 _______________|
                |               |
        2    2(13)5          6(18)15
                |               ^
        3    3(14)4     7(19)10   11(21)14
                           |          |
        4               8(20)9    12(22)13

Support and Development

To report bugs, use the issue tracker <https://github.com/uralbash/sqlalchemy_mptt/issues>_.

We welcome any contribution: suggestions, ideas, commits with new futures, bug fixes, refactoring, docs, tests, translations, etc...

If you have question, contact me sacrud@uralbash.ru or #sacrud IRC channel |IRC Freenode|

License

The project is licensed under the MIT license.

.. |Build Status| image:: https://travis-ci.org/uralbash/sqlalchemy_mptt.svg?branch=master :target: https://travis-ci.org/uralbash/sqlalchemy_mptt .. |Coverage Status| image:: https://coveralls.io/repos/uralbash/sqlalchemy_mptt/badge.png :target: https://coveralls.io/r/uralbash/sqlalchemy_mptt .. |IRC Freenode| image:: https://img.shields.io/badge/irc-freenode-blue.svg :target: https://webchat.freenode.net/?channels=sacrud

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