DTO

• Data Transfer Object (normally over the network). Some said this is anti pattern
• Helpful when you want to only expose a few properties (not the whole class).
• Mainly for serialisation or parsing

Example

For example, if we have the following class for our domain models:

public class User {

    private String id;
    private String name;
    private String password;
    private List<Role> roles;

    public User(String name, String password, List<Role> roles) {
        this.name = Objects.requireNonNull(name);
        this.password = this.encrypt(password);
        this.roles = Objects.requireNonNull(roles);
    }

    // Getters and Setters

   String encrypt(String password) {
       // encryption logic
   }
}

public class Role {

    private String id;
    private String name;

    // Constructors, getters and setters
}

Then the DTO could be as the following:

public class UserDTO {
    private String name;
    private List<String> roles;
    
    // standard getters and setters
}

Since the DTO is to interact and sent to the API client, we hide the password and only display relevant information.

Note:

• DTO should not contains logic
• DTO should only be created if necessary