second one is not a good argument, cascade delete will remove all descendants, but we will have a broken tree, since on delete there are 2 updates to change lft and rgt, so I have only to fight with myself not to be lazy :) and to remove parent_id
On Mon, Nov 9, 2009 at 1:28 AM, Vasile Ermicioi <[email protected]> wrote: > - for using in some queries like direct children (just too lazy to think > how to use lft and rgt :) ) > - cascade delete (if is supported by the database) > > > On Mon, Nov 9, 2009 at 1:18 AM, mdipierro <[email protected]> wrote: > >> >> what do you need parent_id for when you have lgt and rgt? >> >> >> >> On Nov 8, 5:10 pm, elffikk <[email protected]> wrote: >> > Hi, >> > >> > I started a nested sets implementation >> > Just sharing the code. I welcome any thoughts you have >> > >> > 2 files - nstree_controller (just quick and dirty tests of the model), >> > and nstree_model >> > >> > [nstree_controller :] >> > >> > t1 = nstree(db, db.tree1) >> > >> > def index(): >> > return dict(message="Version " + nstree.version) >> > >> > def test_path(): >> > _id = 33 >> > return dict(message = " > ".join([node.name for node in t1.path >> > (_id)])) >> > >> > def test_removetree(): >> > _id = request.vars.id if request.vars.id else 3 >> > t1.remove_tree(_id) >> > return dict(message="Success") >> > >> > def test_delete(): >> > _id = request.vars.id if request.vars.id else 19 >> > node = t1.delete(_id) >> > return dict(message= node.name + " deleted ") >> > >> > def test_get(): >> > _id = request.vars.id if request.vars.id else 15 >> > #nodes = t1.ancestors(_id) >> > #nodes = t1.descendants(_id) >> > nodes = t1.children(_id) >> > return dict(message= ", ".join([node.name for node in nodes])) >> > >> > def test_gettree(): >> > root_id = request.vars.root_id if request.vars.root_id else 1 >> > nodes = t1.tree(root_id) >> > return dict(message="Count "+str(len(nodes))) >> > >> > def test_add(): >> > root_id = request.vars.root_id if request.vars.root_id else >> > t1.roots()[0].id >> > r1 = t1.add(root_id, name='1') >> > r2 = t1.add(root_id, name='2') >> > r3 = t1.add(root_id, name='3') >> > t1.add(r1, name='11') >> > t1.add(r1, name='12') >> > return dict(message="Success") >> > >> > def test_create_roots(): >> > ''' >> > t1.create_root(name='root1') >> > t1.create_root(name='root2') >> > t1.create_root(name='root3') >> > t1.create_root(name='root4') >> > ''' >> > roots = t1.roots() >> > return dict(message="Roots count : " + str(len(roots))) >> > >> > [nstree_model:] >> > >> > db.define_table('tree1', >> > SQLField('name', "string", 128), >> > SQLField('lft','integer'), >> > SQLField('rgt','integer'), >> > SQLField('level','integer'), >> > SQLField('root_id','integer'), >> > SQLField('parent_id','reference tree1'), >> > ) >> > # >> > # A Nested Sets implementation >> > # need to pass a table with following fields: >> > # lft, rgt, level, parent_id, root_id - all fields of type int >> > # ------- >> > # Notes: >> > # - table can contain multiple roots >> > # >> > class nstree: >> > version = "1.0.0.04" >> > def __init__(self, db, dbtable): >> > self.db = db >> > self.dbtable = dbtable >> > #self.lft = dbtable.lft >> > #self.rgt = dbtable.rgt >> > #self.level = dbtable.level >> > #self.parent_id = dbtable.parent_id >> > #self.root_id = dbtable.root_id >> > # >> > # Methods for building tree (create, delete nodes) >> > # >> > def create_root(self, **fields): >> > _id = self.dbtable.insert(lft=1, rgt=2, level=0, **fields) >> > _root = self.dbtable[_id] >> > _root.update_record(root_id = _id) >> > return _root >> > def add(self, parent_id, **fields): return self.add_last_child >> > (parent_id, **fields) >> > def add_last_child(self, parent_id, **fields): >> > _parent = self.dbtable[parent_id] >> > q1 = self.dbtable.rgt >= _parent.rgt >> > q2 = self.dbtable.lft >= _parent.rgt >> > q3 = self.dbtable.root_id == _parent.root_id >> > self.db(q1)(q3).update(rgt=self.dbtable.rgt+2) >> > self.db(q2)(q3).update(lft=self.dbtable.lft+2) >> > return self.dbtable.insert( >> > parent_id = parent_id, >> > lft = _parent.rgt, >> > rgt = _parent.rgt+1, >> > level = _parent.level+1, >> > root_id = _parent.root_id, >> > **fields >> > ) >> > def delete(self, id): return self.remove(id) >> > def remove(self, id): >> > node = self.dbtable[id] >> > delta = node.rgt - node.lft + 1 >> > q1 = self.dbtable.lft >= node.lft >> > q2 = self.dbtable.rgt <= node.rgt >> > self.db(q1)(q2).delete() >> > self.db(self.dbtable.lft > node.rgt).update(lft = >> > self.dbtable.lft - delta) >> > self.db(self.dbtable.rgt > node.rgt).update(rgt = >> > self.dbtable.rgt - delta) >> > return node >> > def remove_descendants(self, id): >> > node = self.dbtable[id] >> > delta = node.rgt - node.lft + 1 >> > q1 = self.dbtable.lft > node.lft >> > q2 = self.dbtable.rgt < node.rgt >> > self.db(q1)(q2).delete() >> > self.db(self.dbtable.lft > node.rgt).update(lft = >> > self.dbtable.lft - delta) >> > self.db(self.dbtable.rgt > node.rgt).update(rgt = >> > self.dbtable.rgt - delta) >> > def remove_tree(self, id): >> > self.db(self.dbtable.root_id == id).delete() >> > # >> > # Methods for retrieving nodes >> > # >> > def roots(self): return self.db(self.dbtable.lft == 1).select() >> > def tree(self, root_id): return self.db(self.dbtable.root_id == >> > root_id).select(orderby = self.dbtable.lft) >> > def ancestors(self, id): >> > node = self.dbtable[id] >> > q1 = self.dbtable.lft < node.lft >> > q2 = self.dbtable.rgt > node.rgt >> > q3 = self.dbtable.root_id == node.root_id >> > return self.db(q1)(q2)(q3).select(orderby = self.dbtable.lft) >> > def path(self, id): >> > node = self.dbtable[id] >> > q1 = self.dbtable.lft <= node.lft >> > q2 = self.dbtable.rgt >= node.rgt >> > q3 = self.dbtable.root_id == node.root_id >> > return self.db(q1)(q2)(q3).select(orderby = self.dbtable.lft) >> > def descendants(self, id): >> > node = self.dbtable[id] >> > q1 = self.dbtable.lft > node.lft >> > q2 = self.dbtable.rgt < node.rgt >> > q3 = self.dbtable.root_id == node.root_id >> > return self.db(q1)(q2)(q3).select(orderby = self.dbtable.lft) >> > def children(self, id): return self.db(self.dbtable.parent_id == >> > id).select(orderby = self.dbtable.lft) >> > # >> > # Methods for checking or getting state of node(s) >> > # >> > def num_children(self, node): return int((node.rgt-node.lft-1)/2) >> > def is_root(self, node): return node.id == node.root_id >> > def is_leaf(self, node): return node.lft == node.rgt-1 >> > def is_child(self, node1, node2): return node1.lft > node2.lft >> > and node1.rgt < node2.rgt >> >> >> > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web2py-users" group. 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