RE: How to add a third field to a join table?

From: Gentry, Michael \(Contractor\) ("Gentry,)
Date: Thu Sep 22 2005 - 16:41:33 EDT

  • Next message: Joseph Hannon: "Re: How to add a third field to a join table?"

    User <-->> UserToRole <<--> Role
     
    I'd also add helper methods to your User (and perhaps Role) subclass.
    Things like addRole(Role role). This helper method would create a new
    UserToRole and set the user/role relationships in the new UserToRole
    object. This will keep the code which uses the User a bit cleaner.
     
    You would persist everything with a normal dataContext.commitChanges()
    when you are done.
     
    /dev/mrg
     
     
    -----Original Message-----
    From: Joseph Hannon [mailto:jah.volcan..mail.com]
    Sent: Thursday, September 22, 2005 4:14 PM
    To: cayenne-use..bjectstyle.org
    Subject: Re: How to add a third field to a join table?

            Cool. Will you tell me more about the relationship of User and
    Role, meaning, should they now be to many, to one? Given a User and a
    few Role objects, how exactly would I persist that combination? Persist
    through User, Role, create a new UserToRole for each User/Role I will
    store and persist it?
            
            Thanks,
            Joseph
            
            
            On 9/22/05, Andrus Adamchik <andru..bjectstyle.org> wrote:

                    Actually now that the join table has meaningful
    attributes you should
                    create an ObjEntity for it. Flattened relationships that
    you setup is
                    a shortcut to hide meaningless tables. In your case it
    is no longer
                    appropriate.
                    
                    Andrus
                    
                    
                    On Sep 22, 2005, at 7:04 AM, Joseph Hannon wrote:
    > I successfully implemented the seven step instruction
    piece that
    > Todd O'Bryan detailed in the post 'Many to Many
    Relation'. That
    > would be a great addition to the Cayenne docs!
    >
    > Now, I need to add a new field to the link table
    'UserToRole'. This
    > new field, 'YYZ', will represent the importance of a
    specific Role
    > for a User as an integer. YYZ clearly cannot be in
    the Role table
    > since Roles are reused and each may have a different
    importance.
    > Based on Todd's instructions, I don't have an
    objEntity called
    > UserToRole, and now I suspect I will need one due to
    this new
    > field. Currently, I can retrieve a List of Role
    objects from
    > within User, but how would I get to this new field
    YYZ?
    >
    > Please advise.
    >
    > Thanks,
    > Joseph
                    
                    

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