Re: [SQLObject] Additionnal datas on joins

[Ian B. <ia...@co...>]

On Mon, 2003-07-28 at 03:31, Fran=E7ois Girault wrote:
> Hi all,
>=20
> in some cases, there's additionnal datas in relation table. For
> example, the rank if the relation is ordered, or a lock object for
> edition...=20

I'm not entirely clear on what you want here.  I think you are
describing a whole set of features, and maybe you're thinking about how
to describe those.

I'm not actually very happy with the _columns (now defunct), _idName,
_joins, etc., style.  So alternative syntaxes are good.

If the feature needs a name (like columns and joins do), then attributes
is the way to go.  Neither ordering or locks need a name, though -- they
would be used implicitly in other areas.  __order__ and __lock__ are
possibilities -- at least they are obviously magic, but I'm also a
little reluctant to overuse the double-underscore variables.  Though I
don't really believe the idea that double underscore variables are
preserved for Python.  Python grows such variables very slowly.

I'm open to other ideas.  Nested classes, like:

class InvoiceItem(SQLObject):

    invoiceOrder =3D IntCol()

    class meta:
        orderBy =3D invoiceOrder
        lock =3D 'optimistic'

Certainly easily extensible, without a not-so-bad syntax.  It would lead
to the separate mapping object that some people sometime want...

But maybe that's not what you are asking about ;)  I'm not entirely
clear on the rest of this...

> It's very common to see that.
>=20
> So I'm thinking about how to implement this :
>=20
>  - one (ugly but usuable) way to do that without modifying SQLObject
> is to describe the join like an entity with 2 foreign keys, and then
> specifying the additionnal columns as usual.
>=20
>  - a cleaner way would be to add the columns to the join declaration,
> and then attach these columns to the entities retrevied when
> performing the join.

I don't think this would be threadsafe -- things shouldn't be attached
to SQLObject instances unless they really belong to the instance, not
the instance in a specific context.

But as I reread this, I'm really not clear about what you're trying to
do.  An example might clarify (though I probably won't be able to follow
up)

  Ian