To be clear this is not a feature request. I could use a hit how to build a fake mapper like this if not compatible in certain cases.
On Jun 6, 5:52 pm, Victor Olex <victor.o...@vtenterprise.com> wrote: > Thanks. Model that we work with has tables, which have no unique > constraints. Keys can be inferred from data contained specified in ORM > maping but there is no guarantee that this will always work because > data may change. Still one could argue a case where mapping such table > to a class has merit even if far removed from all the benefits of > SQLAlchemy ORM. > > On Jun 6, 4:55 pm, Michael Bayer <mike...@zzzcomputing.com> wrote: > > > > > > > > > There's two variants to this question, and I can't tell which one you're > > asking for. > > > If the views in question do in fact have candidate keys, that is, columns > > which uniquely identify a row, you just specify those either to the Table > > or mapper() as the columns that uniquely identify the row. They don't > > have to be considered "primary" by the database in any formal way. > > > If OTOH you have views which truly have duplicate rows and no candidate key > > of any kind, the ORM won't do that. As you probably know, the primary key > > thing is more or less the spine of mapper() and Query, and there's really > > no way the ORM could be refactored, without a great loss of stability and > > performance, to make this requirement optional. > > > If you're looking for duplicate rows to come back as individual objects, > > Query() can be handed Table objects to load rows from, so a custom Query > > subclass that wraps named tuples into objects could possibly approximate > > this effect. > > > On Jun 6, 2012, at 3:01 PM, Victor Olex wrote: > > > > With the understanding that we would loose the ability to properly > > > track the sate of a mapped object and ability to update or insert in > > > ORM and likely the ability to correctly use relationships as well - > > > how can one accomplish a mapper, which would work on tables (views) > > > without any key, which uniquely identify records in it? > > > > The rationale for this question is to be able to be able to operate on > > > these tables in object (ORM) context and to join them in queries with > > > other normally mapped classes for reading purposes only. The ideal > > > solution would be perhaps a different Declarative Base class using a > > > modified mapper. > > > > -- > > > 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 > > > athttp://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.
