Best Practices For Mapping DTO to Domain Object?

Question

I\'ve seen a lot of questions related to mapping DTOs to Domain Objects, but I didn\'t feel they answered my question. I\'ve used many methods before and have my own opinio

Answer 1

You could use an automapper such as the one written by Jimmy Bogard which has no connection between the objects and relies on naming conventions being adhered to.

Answer 2

A benefit of having a mapper that sits between your domain and your DTO is not as appearent when you are only supporting a single mapping, but as the number of mappings increases, having that code isolated from the domain helps keep the domain simpler and leaner. You won't be cluttering your domain with a lot of extra weight.

Personally, I try and keep the mapping out of my domain entities and put the responsibility in what I call "Manager / Service layer". This is a layer that sits between the application and the respository(ies), and provides business logic such as workflow coordination (If you modify A, you might have to also modify B so service A will work with Service B).

If I had a lot of possible ending formats, I might look at creating a plugable formatter that could use the Visitor pattern, for example to transform my entities, but I've not found a need yet for anything this complex.

Answer 3

Another possible solution: http://glue.codeplex.com.

Features:

• Bidirectional mapping
• Automatic mapping
• Mapping between different types
• Nested mapping and Flattening
• Lists and Arrays
• Verification of relations
• Testing the mapping
• Properties, Fields and Methods

Answer 4

We can use Factory, Memento, and Builder pattern for that. Factory hide the details on how to create instance of domain model from DTO. Memento will take care the serialization/deserialization of the domain model to/from DTO and can even access private members. The Builder will allows mapping from DTO to domain with fluent interface.

Answer 5

Why not we can do like this?

class UserDTO {
}

class AdminDTO {
}

class DomainObject {

 // attributes
 public DomainObject(DTO dto) {
      this.dto = dto;
 }     

 // methods
 public function isActive() {
      return (this.dto.getStatus() == 'ACTIVE')
 }

 public function isModeratorAdmin() {
      return (this.dto.getAdminRole() == 'moderator')
 }

}


userdto = new UserDTO();
userdto.setStatus('ACTIVE');

obj = new DomainObject(userdto)
if(obj.isActive()) {
   //print active
}

admindto = new AdminDTO();
admindto.setAdminRole('moderator');

obj = new DomainObject(admindto)
if(obj.isModeratorAdmin()) {
   //print some thing
}

@FrederikPrijck (or) someone: Please suggest. In the above example DomainObject is depends on DTO. By this way i can avoid the code to do mapping the dto <--> domainobject.

or DomainObject class can extends the DTO class?

Answer 6

How do you see to implement a constructor inside the DTO class that takes as a parameter a domain object?

Say... Something like this

class DTO {

     // attributes 

     public DTO (DomainObject domainObject) {
          this.prop = domainObject.getProp();
     }

     // methods
}