Save or update for FK relationship Sqlalchemy

Posted by Alex on Stack Overflow See other posts from Stack Overflow or by Alex
Published on 2010-02-27T10:01:36Z Indexed on 2010/03/09 11:36 UTC
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sqlalchemy

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foreign-keys

I've googled, but haven't been able to find the answer to this seemingly simple question.

I have two relations, a customer and an order. Each order is associated to a single cusomter, and therefore has a FK relationship to the customer table. The customer relation only stores customer names, and I have set a unique constraint on the customer table barring duplicate names.

Let's say I create a new order instance and set a customer for the order. Something like:

order_instance.customer = Customer("customer name")

When I save the order instance, SqlAlchemy will complain if a customer with this name already exists in the customer table.

How do I specify to SqlAlchemy to insert into the customer table if a customer with this name doesn't already exist, or just ignore (or even update) to the customer relation? I don't really want to have to check each time if a customer with some name already exists...

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