Hi,
I am working on defining my mapping with SQLAlchemy and I am pretty
much done except one thing. I have a 'resource' object and an
association table 'relation' with several properties and a
relationship between 2 resources. What I have been trying to do almost
successfully so far, is to provide on the resource object 2
properties: parent and children to traverse the tree stored by the
association table. A relation between 2 properties only last for a
while, so there is a start and end date. Only one resource can be the
parent of another resource at a time.
My problem is that if I expire one relation and create a new one, the
parent property is not refreshed. I am thinking maybe there an issue
with the primaryjoin for the parent property of resource.
Here is some code:
resource_table = model.tables['resource']
relation_table = model.tables['resource_relation']
mapper(Resource, resource_table,properties = {'type' :
relation(ResourceType,lazy = False), 'groups' : relation(Group,
secondary = model.tables['resource_group'], backref = 'resources'),
'parent' : relation(Relation, uselist=False, primaryjoin =
and_(relation_table.c.res_id == resource_table.c.res_id,
relation_table.c.end_date > func.now())),
'children' : relation(Relation, primaryjoin =
and_(relation_table.c.parent_id == resource_table.c.res_id,
relation_table.c.end_date > func.now()))})
mapper(Relation, relation_table, properties = {'resource' :
relation(Resource, primaryjoin = (relation_table.c.res_id ==
resource_table.c.res_id)), 'parent' : relation(Resource, primaryjoin =
(relation_table.c.parent_id == resource_table.c.res_id))})
oldrelation = resource.parent
oldrelation.end_date = datetime.today()
relation = self.createRelation(parent, resource)
# Here the relation object has not replaced oldrelation in the
resource object
Hi,
I am working on defining my mapping with SQLAlchemy and I am pretty
much done except one thing. I have a 'resource' object and an
association table 'relation' with several properties and a
relationship between 2 resources. What I have been trying to do almost
successfully so far, is to provide on the resource object 2
properties: parent and children to traverse the tree stored by the
association table. A relation between 2 properties only last for a
while, so there is a start and end date. Only one resource can be the
parent of another resource at a time.
My problem is that if I expire one relation and create a new one, the
parent property is not refreshed. I am thinking maybe there an issue
with the primaryjoin for the parent property of resource.
Here is some code:
resource_table = model.tables['resource']
relation_table = model.tables['resource_relation']
mapper(Resource, resource_table,properties = {'type' :
relation(ResourceType,lazy = False), 'groups' : relation(Group,
secondary = model.tables['resource_group'], backref = 'resources'),
'parent' : relation(Relation, uselist=False, primaryjoin =
and_(relation_table.c.res_id == resource_table.c.res_id,
relation_table.c.end_date > func.now())),
'children' : relation(Relation, primaryjoin =
and_(relation_table.c.parent_id == resource_table.c.res_id,
relation_table.c.end_date > func.now()))})
mapper(Relation, relation_table, properties = {'resource' :
relation(Resource, primaryjoin = (relation_table.c.res_id ==
resource_table.c.res_id)), 'parent' : relation(Resource, primaryjoin =
(relation_table.c.parent_id == resource_table.c.res_id))})
oldrelation = resource.parent
oldrelation.end_date = datetime.today()
relation = self.createRelation(parent, resource)
# Here the relation object has not replaced oldrelation in the
resource object
Any idea ?
Thanks,
Richard Lopes
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