Modify SQL query generated by Spring REST data predictions

Question

EDIT: How to save only the necessary columns in SELECT for Spring Data Conservation Projection?

Spring Data plays are good for getting a subset of columns for generated links, but in the query that is generated behind, all the columns in it.

How can you create projections where also SQL queries have only those columns in SELECT that are in Projection

Answer 1

, , spring ( spring) , - @Query. , :

public interface ActionId {
    String getId(); 
}

@Query("select a.id as id from Action a where a.type = :type")
public List<ActionId> findByType(@Param("type") String type);

, , . , , "Action" id, -

ref: https://github.com/spring-projects/spring-data-examples/blob/master/jpa/example/src/main/java/example/springdata/jpa/projections/CustomerRepository.java

Answer 2

, " ", .

: A bubi B, foo, bar, zed.

B, :

@Projection(name="reduced", types = B.class)
public interface BReduced {
    String foo;
    //exclude bar, for instance
    int zed;
}

A.

@Projection(name="reduced", types = A.class)
public interface AReduced {
    int bubi;
    BReduced b;
}

SQL-?