How To Fetch DTO Via ResultTransformer And Native SQL

Description: Fetching more data than needed is prone to performance penalties. Using DTO allows us to extract only the needed data. In this application we rely on Hibernate, ResultTransformer and native SQL.

Key points:

• use AliasToBeanConstructorResultTransformer for DTO without setters, but with constructor
• use Transformers.aliasToBean() for DTO with setters
• use EntityManager.createNativeQuery() and unwrap(org.hibernate.query.NativeQuery.class)
• starting with Hibernate 5.2, ResultTransformer is deprecated, but until a replacement will be available (probably in Hibernate 6.0) it can be used (read further)
• for using Spring Data Projections check this recipe

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