How to validate inner entities in Spring? - spring

Question

I have a Spring MVC application with javax validation. Is there any way to validate inner entities existence, i.e. many-to-one relationship without marking inner class's id #NotNull and additional long field for FK?
#Entity
#Table
public class MyEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#NotNull
private String name;
#ManyToOne
#JoinColumn(name = "my_inner_entity_id")
#NotNull
private MyInnerEntity innerEntity;
//#Column(name = "my_inner_entity_id") can't use it
//#NotNull
//private Long innerEntityId;
//setters and getters
}
#Entity
#Table
public class MyInnerEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
//#NotNull can't use it
private Long id;
#NotNull
private Integer value;
#OneToMany(mappedBy = "innerEntity")
private Set<MyEntity> entities = new HashSet<>();
//setters and getters
}
#PostMapping
public MyEntity save(#RequestBody #Valid MyEntity entity) {
//save entity
}

Answer 1

Just add #Valid annotation to innerEntity property:
#Valid
#NotNull
#ManyToOne
private MyInnerEntity innerEntity;

Answer 2

Solved it by writing custom validator:
#Documented
#Constraint(validatedBy = InnerIdValidator.class)
#Target({ElementType.METHOD, ElementType.FIELD})
#Retention(RetentionPolicy.RUNTIME)
public #interface InnerId {
String message() default "entity with id is required";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
public class InnerIdValidator implements ConstraintValidator<InnerId, IdObject> {
#Override
public boolean isValid(IdObject idObject, ConstraintValidatorContext constraintValidatorContext) {
return idObject != null && idObject.getId() != null;
}
}