mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-05-15 05:07:16 -04:00
Mike Bayer
93 lines
2.7 KiB
Python
93 lines
2.7 KiB
Python
from sqlalchemy.mapper import *
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from sqlalchemy.schema import *
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from sqlalchemy.sql import *
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import sqlalchemy.util as util
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import tables
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import string, sys
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"""a basic Adjacency List model tree."""
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class NodeList(util.OrderedDict):
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"""extends an Ordered Dictionary, which is just a dictionary that returns its keys and values
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in order upon iteration. Adds functionality to automatically associate
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the parent of a TreeNode with itself, upon append to the parent's list of child nodes."""
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def __init__(self, parent):
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util.OrderedDict.__init__(self)
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self.parent = parent
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def append(self, node):
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node.parent = self.parent
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self[node.name] = node
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def __iter__(self):
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return iter(self.values())
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class TreeNode(object):
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"""a rich Tree class which includes path-based operations"""
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def __init__(self, name=None):
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self.children = NodeList(self)
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self.name = name
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self.parent = None
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self.id = None
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self.parent_id = None
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def append(self, node):
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if isinstance(node, str):
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self.children.append(TreeNode(node))
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else:
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self.children.append(node)
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def __str__(self):
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return self._getstring(0, False)
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def _getstring(self, level, expand = False):
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s = (' ' * level) + "%s (%s,%s)" % (self.name, self.id,self.parent_id) + '\n'
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if expand:
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s += string.join([n._getstring(level+1, True) for n in self.children.values()], '')
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return s
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def print_nodes(self):
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return self._getstring(0, True)
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# define the mapper. we will make "convenient" property
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# names vs. the more verbose names in the table definition
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TreeNode.mapper=assignmapper(tables.trees, class_=TreeNode, properties=dict(
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id=tables.trees.c.node_id,
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name=tables.trees.c.node_name,
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parent_id=tables.trees.c.parent_node_id,
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root_id=tables.trees.c.root_node_id,
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children=relation(TreeNode, primaryjoin=tables.trees.c.parent_node_id==tables.trees.c.node_id, thiscol=tables.trees.c.node_id, lazy=True, uselist=True, private=True),
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))
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node2 = TreeNode('node2')
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node2.append('subnode1')
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node = TreeNode('rootnode')
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node.append('node1')
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node.append(node2)
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node.append('node3')
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node.children['node2'].append('subnode2')
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print node.print_nodes()
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objectstore.commit()
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node.append('node4')
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node.children['node4'].append('subnode3')
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node.children['node4'].append('subnode4')
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node.children['node4'].children['subnode3'].append('subsubnode1')
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del node.children['node1']
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print node.print_nodes()
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objectstore.commit()
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id = node.id
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objectstore.clear()
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print "\n\n\n"
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t = TreeNode.mapper.select(TreeNode.c.id == id)[0]
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print t.print_nodes()
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objectstore.delete(t)
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objectstore.commit()
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