JPA2: How to map only certain table rows to an entity?

Question

I have a table I cannot change with approximately this structure

ID, name, purpose, rubbish...
1, foo, PRICING, ...
2, bar, INVENTORY, ...
3, bar, PRICING, ...

What is the preferred way to map only the lines with purpose=PRICING to an Entity? Is there a way to do this with JPA annotations or do I need a view?

Answer 1

You might use SINGLE_TABLE inheritance strategy, and use "purpose" as discriminator column like this:

@Entity
@Table(name="THE_TABLE")
@Inheritance(strategy=SINGLE_TABLE)
@DiscriminatorColumn(name="purpose", discriminatorType=STRING)
@DiscriminatorValue("PRICING")
public class Pricing{ ... }