Tim Black wrote:
> I'm trying to create more than one RelatedJoin between the same two
> classes. I need to construct many-to-many relationships between Persons
> and Projects, because:
>
> - one project can have multiple clients (when it's an open-source project)
> - one project can have multiple contractors working on it
> - one person can work as a contractor on multiple projects
> - one person can be the client that pays for multiple projects
> - one person can be a client on one project and a contractor on another
> project
>
> Is it possible to do this in SQLObject? How?
>
> I've tried to represent this simply as:
>
> class Person(SQLObject):
> name = StringCol()
> clientProjects = RelatedJoin("Project")
> contractorProjects = RelatedJoin("Project")
>
> class Project(SQLObject):
> name = StringCol()
> clients = RelatedJoin("Person")
> contractors = RelatedJoin("Person")
>
> But, when I add a client to a project in Catwalk, that client appears as
> a contractor as well on the same project! Makes sense; for example, I
> shouldn't expect SQLObject to distinguish between two identical
> references to RelatedJoin("Project"). But how can I distinguish the two
> references properly?
>
> I've tried various combinations of using joinColumn, otherColumn, and
> intermediateTable, but no success yet. The documentation on joinColumn
> and otherColumn is not readily understandable; perhaps a UML diagram of
> the references between the classes and database tables could clarify the
> documentation. The best luck I've had yet was to specify two
> intermediateTables - one for the project_client relation and one for the
> project_contractor relation. But, that resulted in all persons being
> added as clients, even when I tried to add them as contractors.
>
> Tim Black
It seems that joinColumn should answer your problems, but I don't
know... I gave up on SQLObject soon after I started it. I do know that
I've found this representation fairly straightforward in SQLAlchemy.
Paul
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