jpa websphere entity id non-existent errors

Question

Good evening. When I attempt to create jpa entities using a database connection I am getting some exceptions. Something about id non-existent. I suspect it has something to do with the fact that some of the tables have no primary key. Because when I go through each entity and give it a primary key, the error clears up. How can I create entities on tables that have no primary keys? I am using websphere integration developer (wid) btw.

score 1 · Accepted Answer · answered Mar 18 '12 at 23:08

All entities have an Id, that is how they work - or more accurately how the specification states it. If there are tables in the database you want to map to entities and the tables don't have a primary key there are several options availble to you.

Add a generated Id (managed by JPA or DB) to the table - suggested if you have that freedom.
Use a couple of the existing columns in the table as the entity Id (choosing the least numbers necessary to make sure the Id becomes unique).
Use all columns, even if there is a theoretical chance of their combination not being unique (would mess up the table/db so care should be taken even in the java layers to not let that happen)
... might be more alternatives I can't think of right now

Should be rather easy to find information about how to do alternative 2 and 3 via a search for JPA and CompositeKey.

Good Luck

Didn't think of that. I might end up doing that. Thanks. – SoftwareSavant Mar 19 '12 at 10:47 — SoftwareSavant, Mar 19 '12 at 10:47
could I perhaps generate embedded types instead? – SoftwareSavant Mar 19 '12 at 12:13 — SoftwareSavant, Mar 19 '12 at 12:13
Instead of entities or instead as Id for the entity? – esej Mar 19 '12 at 15:02 — esej, Mar 19 '12 at 15:02

jpa websphere entity id non-existent errors

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