setting the newDataBase flag to False, heres the echo at the end:
2007-03-08 14:30:26,428 INFO sqlalchemy.engine.base.Engine.0x..50 BEGIN
2007-03-08 14:30:26,435 INFO sqlalchemy.engine.base.Engine.0x..50
DELETE FROM treenodes WHERE treenodes.node_id = ?
2007-03-08 14:30:26,441 INFO sqlalchemy.engine.base.Engine.0x..50
[[5], [6]]
2007-03-08 14:30:26,447 INFO sqlalchemy.engine.base.Engine.0x..50
DELETE FROM treenodes WHERE treenodes.node_id = ?
2007-03-08 14:30:26,448 INFO sqlalchemy.engine.base.Engine.0x..50
[[2], [3], [4]]
2007-03-08 14:30:26,456 INFO sqlalchemy.engine.base.Engine.0x..50
DELETE FROM treenodes WHERE treenodes.node_id = ?
2007-03-08 14:30:26,458 INFO sqlalchemy.engine.base.Engine.0x..50 [1]
2007-03-08 14:30:26,466 INFO sqlalchemy.engine.base.Engine.0x..50
DELETE FROM treedata WHERE treedata.data_id = ?
2007-03-08 14:30:26,467 INFO sqlalchemy.engine.base.Engine.0x..50
[[1], [2]]
2007-03-08 14:30:26,471 INFO sqlalchemy.engine.base.Engine.0x..50 COMMIT
run sqlite3 against the file, check the tables:
z-eeks-Computer:~/dev/sqlalchemy classic$ sqlite3 tutorial_modified.db
SQLite version 3.3.13
Enter ".help" for instructions
sqlite> select * from treenodes;
sqlite> select * from treedata;
sqlite>
so, its all deleted. filesize is irrelevant.
On Mar 8, 2007, at 11:56 AM, Andrea Gavana wrote:
> import os
> from sqlalchemy import *
> from sqlalchemy.util import OrderedDict
>
>
> class TreeData(object):
> def __init__(self, value=None):
> self.id = None
> self.value = value
> def __repr__(self):
> return "TreeData(%s, %s)" % (repr(self.id), repr(self.value))
>
> class NodeList(OrderedDict):
> """subclasses OrderedDict to allow usage as a list-based
> property."""
> def append(self, node):
> self[node.name] = node
> def __iter__(self):
> return iter(self.values())
>
> class TreeNode(object):
> """a rich Tree class which includes path-based operations"""
> def __init__(self, name):
> self.children = NodeList()
> self.name = name
> self.parent = None
> self.id = None
> self.parent_id = None
> self.value = None
>
> def setdata(self, data):
> self.data = data
>
> def getdata(self):
> return self.data
>
> def append(self, node):
> if isinstance(node, str):
> node = TreeNode(node)
> node.parent = self
> self.children.append(node)
>
> def __repr__(self):
>
> return self._getstring(0, False)
> def __str__(self):
> return self._getstring(0, False)
>
> def _getstring(self, level, expand = False):
> s = (' ' * level) + "%s (%s,%s, %d)" % (self.name,
> self.id,self.parent_id,id(self)) + '\n'
> if expand:
> s += ''.join([n._getstring(level+1, True) for n in
> self.children.values()])
> return s
>
> def print_nodes(self):
> return self._getstring(0, True)
>
>
> class TheEngine(object):
>
> def __init__(self, newDataBase=True):
>
> if newDataBase and os.path.isfile("tutorial_modified.db"):
> os.remove("tutorial_modified.db")
>
> self.engine = create_engine('sqlite:///
> tutorial_modified.db', echo=False)
> metadata = BoundMetaData(self.engine)
>
> trees = Table('treenodes', metadata,
> Column('node_id', Integer, Sequence
> ('treenode_id_seq',optional=False), primary_key=True),
> Column('parent_node_id', Integer, ForeignKey
> ('treenodes.node_id'), nullable=True),
> Column('node_name', String(50), nullable=False),
> Column('data_ident', Integer, ForeignKey
> ('treedata.data_id'))
> )
>
>
> treedata = Table("treedata", metadata,
> Column('data_id', Integer, primary_key=True),
> Column('value', String(100), nullable=False)
> )
>
> mapper(TreeNode, trees, properties=dict(id=trees.c.node_id,
>
> name=trees.c.node_name,
>
> parent_id=trees.c.parent_node_id,
> children=relation
> (TreeNode, cascade="all", backref=backref("parent", remote_side=
> [trees.c.node_id]), collection_class=NodeList),
> data=relation(mapper
> (TreeData, treedata, properties=dict(id=treedata.c.data_id)),
> cascade="delete,delete-orphan,save-update", lazy=False))
> )
>
> metadata.create_all()
> self.session = create_session()
>
> if newDataBase:
> self.CreateNodes()
> else:
> self.LoadNodes()
>
>
> def CreateNodes(self):
>
> node2 = TreeNode('node2')
> node2.setdata(TreeData("Hello "*10000))
>
> node2.append('subnode1')
>
> node = TreeNode('rootnode')
> node.setdata(TreeData("World "*10000))
>
> node.append('node1')
> node.append(node2)
> node.append('node3')
> node.children['node2'].append('subnode2')
>
> print "\n\n\n----------------------------"
> print "Created new tree structure:"
> print "----------------------------"
> print node.print_nodes()
>
> self.session.save(node)
> self.session.flush()
>
> print "\n\n\n----------------------------"
> print "DATABASE SIZE: ", os.stat("tutorial_modified.db")[6]/
> 1000.0, "Kb"
> print "----------------------------"
>
>
> def LoadNodes(self):
>
> self.session.clear()
> t = self.session.query(TreeNode).select
> (TreeNode.c.name=="rootnode")[0]
>
> print "\n\n\n----------------------------"
> print "Check the previous tree structure:"
> print "----------------------------"
> print t.print_nodes()
>
> print "\n\n----------------------------"
> print "Deleting all the nodes from DB"
> print "----------------------------"
>
> self.session.delete(t)
> del t
> self.session.flush()
>
> print "\n\n----------------------------"
> print "DATABASE SIZE: ", os.stat("tutorial_modified.db")[6]/
> 1000.0, "Kb"
> print "----------------------------"
>
>
> # AG: Just modify this variable, the first time to create a new
> # database use True, then use False to see what happens by
> # loading the existing database
> newDataBase = True
>
> def main():
> engineclass = TheEngine(newDataBase)
>
> if __name__ == "__main__":
> main()
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