Using Data annotation on Java DTO class

Question

I have confusion in using Data annotation to DTO class. Here is my sample class.

@Data
public class MyClass {
   private Long id;
   private String name;
}

I've read online that using Data annotation specifically on DTO class will allow the values of the fields to be changed by use of the generated setters.

Should I remove the lombok Data annotation? And implement the getters and setters manually.

Thanks :)

Answer 1

I would avoid @Data for DTOs since it has too many pitfalls. First of all as you mentioned it is mutable which you don't really want for a DTO. And despite it being mutable, it implements equals() and hashCode() which is only asking for trouble.

You can use @Value for an immutable DTO. For an incoming DTO you may need to add lombok.anyConstructor.addConstructorProperties to your lombok.config, which will allow libraries like jackson to deserialize to your POJO without a default constructor.

Answer 2

By default the @Data lombok annotation will generate setters and getters for all fields in the class.

If you want an immutable data transfer object, annotate it as @Value instead.

If you want a mixure of some immmutable values and some mutable values in your MyClass type, for instance you might want the id field to be immutable and the rest mutable, you would use the @Setter annotation on the field you want to be immutable, specifying an AccessLevel of NONE. For instance:

@Data
public class MyClass {
   @Setter(AccessLevel.NONE)
   private Long id;
   private String name;
}

This will generate a getter but no setter for the id, and a getter and setter for the name.