How to prevent tight coupling when using EF models in ViewModels and Services (WPF MVVM)

Question

Hello,

In a WPF MVVM application, I'm using a layered architecture:

• Data Layer: EF Core models (e.g., Book, Member)
• Business Layer: Service classes
• Presentation Layer: WPF ViewModels

Currently, I use EF entity classes directly in my service methods and ViewModel properties.

Example:

public class BookService
{
    public Book GetById(int id); // using EF entity
}
public class BookViewModel
{
    public Book SelectedBook { get; set; } // also EF entity
}

I want to avoid tight coupling between layers.

✅ What is the best way to replace EF entities in the ViewModel layer without breaking the architecture?

• Should I use DTOs in the service layer and map them manually or with a tool like AutoMapper?

• Is there a recommended lightweight method to map between EF entities and DTOs for simple CRUD apps?

Thanks in advance.