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  • Rank 193,679 (Top 4 %)
  • Language
    Python
  • License
    MIT License
  • Created about 10 years ago
  • Updated 4 months ago

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Repository Details

SQLAlchemy nested sets mixin (MPTT)

Build Status Coverage Status

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/

Nested sets traversal

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:

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

PyPi:

pip install sqlalchemy_mptt

Source:

pip install -e .

Usage

Add mixin to model

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

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

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

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)

Nested sets multitree

Nested sets multitree

Move inside

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

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

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.

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

If you have question, contact me [email protected] or #sacrud IRC channel IRC Freenode

License

The project is licensed under the MIT license.

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