sqlalchemy-mptt
Advanced tools
SQLAlchemy mixins for implementing tree-like models using Modified Pre-order Tree Traversal (MPTT) / Nested Sets
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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.
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 .
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!
.. 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
.. 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
.. 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
.. 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
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 any questions:
Discussion board <https://github.com/uralbash/sqlalchemy_mptt/discussions>_Refer the detailed contribution guide in the docs <https://sqlalchemy-mptt.readthedocs.io/CONTRIBUTING.html>_
for more information on setting up the development environment, running tests, and contributing to the project.
The project is licensed under the MIT license.
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Versions releases 0.2.x & above ###############################
see issues #109, #111, #112 & #113
see issues #104 & #110
weakref.WeakSet instead of rolling our own
weak reference set.after_flush_postexec execution path for CPython & PyPy.get_siblings.see issue #97
see issues #63, #87, #89 & #90
see issue #64
django_mptt methods get_siblings and get_childrensee PR #61
see issue #57
see issue #56
see PR #51
see PR #50
parent_id to dynamically match the type of the primary_keyFAQs
SQLAlchemy mixins for implementing tree-like models using Modified Pre-order Tree Traversal (MPTT) / Nested Sets
We found that sqlalchemy-mptt demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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