How to ignored field in named query without creating specific domain model

Question

I want to select object with specific field, but stored object in existing model.

@Entity
public class Car {

@Id
private Integer id;
private String name;
private String type;
private Integer year;

public Integer getId() {
    return id;
}

public void setId(Integer id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getType() {
    return type;
}

public void setType(String type) {
    this.type = type;
}

public Integer getYear() {
    return year;
}

public void setYear(Integer year) {
    this.year = year;
}

}

My repository.

public interface CarRepository extends JpaRepository<Car, Integer>{

    @Query("SELECT c.name, c.year FROM Car c WHERE c.year = :year")
    List<Car> findAll(@Param("year") Integer year);

}

But this will give me error:

Failed to convert from type java.lang.Object[] to type com.sample.model.Car for value '{Chevrolet, 2009}'; nested exception is org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type java.lang.Integer to type com.sample.model.Car

Answer 1

You can use dynamic instantiation. Something like this

select new Car(c.name, c.year) FROM Car c WHERE c.year = :year

or you can use a result transformer (without @Query). And you can see this for some thoughts about partial objects loading.

UPDATE

And It needs to have Car(String name, Integer year) constructor in Car and default constructor too.