Set foreign key of entity without loading the referenced entity

Support
#1

Is it possible to set the foreign key of an entity without loading the referenced entity? E.g. I want to set order.customer_ID instead of order.customer although order has only the property “customer”.

For reading of the foreign key there is a helper method, but not for setting.
persistence.getTools().getReferenceId(order, “customer”)

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#2

You can do it using EntityManager.getReference() method - it creates an instance suitable for being a reference.
For example:


EntityManager em = persistence.getEntityManager();
order.setCustomer(em.getReference(Customer.class, customerId));
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#3

Thanks for the fast reply.

I think

 em.getReference(...)

also loads the referenced entity (at least the ID) from the database? So it seems not possible to just set the foreign id (customer id) without a database select command?

#4

It doesn’t access DB, otherwise it would be the same as find(). It just creates an empty instance with ID in memory, which is what your need for saving a reference.

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