NHibernate many-to-many mapping to existing objects
I'm having some issues with a many-to-many relationship I am trying to create. The goal is to save a customer and which products they are allowed to purchase. The products are not unique to a customer and will ALWAYS exist in the database before we try to associate a customer to them.
My mapping for the association currently looks like...
<set name="AllowedProducts" table="Customer_AllowedProducts">
<key column="CustomerId"></key>
<many-to-many class="Product" column="ProductId"/>
</set>
If I try to save a Customer I get a NHibernate.TransientObjectException
referencing the product. I understand that I could add cascade to the set, but I NEVER want to update or save a pr开发者_JAVA百科oduct when saving a customer, we only want to map a customer to existing products.
I should note that the customer I'm trying to save is coming in from a webservice call and therefore does not reference products that have been previously loaded into the session. I would like to avoid have to load every product that will be mapped into the session.
Thanks
Your code should look like this:
customer.AllowedProducts.Add(session.Load<Product>(productIdFromTheRequest));
Instead of what you are probably doing:
customer.AllowedProducts.Add(new Product {Id = productIdFromTheRequest});
It's worth noting that Load
never goes to the DB; it just returns a proxy (or a retrieved instance, if one is present in the current session)
You will have to attach the product to hibernate session so that they become managed entity. As far as I know, there is no other way out.
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