Mapping a SQL View with no Primary Key to JPA Entity

Question

In my Java App I want to get information that is stored in my Oracle Database, using JPA. In my Database I have a View, with a set of columns that I got from some other tables. I want to map that View. However, my View doesn't have a Primary Key, so I can't create a JPA Entity. I thought about use 2 columns as Foreign Keys.

What's the best way of implementing that? I've seen so many different approaches, that I can't decide which is the best for this case.

Answer 1

One way to solve this is use a composite primary key by just adding the @Id annotation to the appropriate fields.

Answer 2

There is no best approach. As that is a View, you will never insert any data in it, meaning you can simply define a Primary Key over any of existing fields. Also you could try to mark that field with insertable=false, updatable=false.

UPDATE

You know better your data, but in general in a view you cannot guarantee that all records are unique, which is why you should in general avoid working directly with entities from the view. I would suggest rather working with a Wrapper class, something like:

SELECT new com.domain.MyWrapper(field1, field2, field3, field4,...) FROM ViewEntity