On Mar 16, 2011, at 8:12 PM, zaza witch wrote:
> Hi everyone, > > I am currently in work experience ... > > The first step of my work was to build a small application using > sqlalchemy. > > Association proxy seems to allow to simplify many-to-many > relationships management. > Can i use it to store define a class with an attribute which is a list > of string (or integers ...) ? I recently put up an example of this which deals with lists of dicts of integers, it can be adapted to do lists of strings: http://groups.google.com/group/sqlalchemy/msg/342a8c4d814d520a > Let me explain: > > With association proxy, i can do something like: > > class Service(Base): > __tablename__ = 'service' > id = Column('s_id', Integer, primary_key=True) > name = Column('s_name', String(63), unique=True) > class NodeService(Base): > __tablename__ = 'node_service' > node_id = Column('n_id', Integer, ForeignKey('node.n_id'), > primary_key=True) > service_id = Column('s_id', Integer, ForeignKey('service.s_id'), > primary_key=True) > service = relationship(Service lazy='joined') > class Node(Base): > __tablename__ = 'node' > id = Column('n_id', Integer, primary_key=True) > node_services = relationship(NodeService, cascade="all, delete- > orphan", lazy='joined') > services = AssociationProxy('nodes_services', 'service', lambda > service: NodeService(service=service)) > ... > mynode = Node() > mynode.services.append(Service("myservice")) > # instead of > mynode.node_services.append(NodeService(service=Service("myservice") > session.add(mynode) > > > Is there a way to suppress the Service class in order to handle a list > of string (from python point of view) and have something like: > > class NodeAttribute(Base): > __tablename__ = 'node_attribute' > node_id = Column('n_id', Integer, ForeignKey('node.n_id'), > primary_key=True) > attribute = Column('na_id', String, primary_key=True) > class Node(Base): > __tablename__ = 'node' > id = Column('n_id', Integer, primary_key=True) > node_services = relationship(NodeService, cascade="all, delete- > orphan", lazy='joined') > node_attributes = relationship(NodeAttribute cascade="all, delete- > orphan", lazy='joined') > services = AssociationProxy('nodes_services', 'service', lambda > service: NodeService(service=service)) > attributes = AssociationProxyLike('node_attributes', ?, ?) > > mynode = Node() > mynode.attributes.append("myattribute") > # instead of > mynode.node_attributes.append(NodeAttribute("myattribute")) > # attributes look like a list of string (with append/del functions) > session.add(mynode) > > > > The second step is to replace sqlalchemy+database by something > else ... i will make an other message on the topic > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalchemy@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
