Map any collection with NamedNativeQuery and SqlResultSetMapping

Question

So I am writing native queries because they are very complex to get all the needed data and so on. I am currently facing a problem which is normally done by Hibernate/JPA etc.

Imagine the following:

@Entity
FooEntity{
     @Id
     public Long id;
     @ManyToMany
     public List<FeeEntity> feeEntities;
}

@Entity
FeeEntity{
     @Id
     public Long id;
     @Column
     public String name;
}

And some DTO

FooDTO{
     private final Long id;
     private final List<FeeDTO> someStrings;

     public FooDTO(Long id, List<FeeDTO> feeDtos){
          ...
     }
}

My @SqlResultSetMapping looks basically like

@SqlResultSetMapping(name = "FooDTO", 
     classes = @ConstructorResult(targetClass = FooDTO.class, columns = {
          @ColumnResult(name = "id", type = Long.class),     
          //TODO @ColumnResult(name = "feeDtos", type = FeeDtos.class)     
     })
)

The named native query looks something like:

@NamedNativeQueries({
    @NamedNativeQuery(
                name = "FooData",
                query = "SELECT MAINSELECT.ID AS id, " +
                        "???" +
                        " FROM Foo MAINSELECT WHERE ... " +
                        ...,
                resultSetMapping = "FooDTO")
})

How do I have to write the native query? Is this even possible without a subquery or do I have to do/execute a subquery for each datarow of the result? I was not able to find something on beloved google.

Answer 1

That's not possible.

The result of SQL query is always a table. So there are no nested tables and hence you cannot map it to a Collection.