How are the models between layers organized?

In Go architecture, models between layers are usually organized through clear separation of responsibilities and data transfer.

• DTO (Data Transfer Objects) — structures used for transferring data between layers (e.g., between controller and service).
• Domain models — reflect business logic and rules, often located in the business logic layer.
• Persistence models — structures that correspond to database tables, used in the data access layer.

Organizing models between layers helps avoid tight coupling and facilitates testing and maintenance.

Example:

// Persistence model
type UserEntity struct {
    ID    int
    Name  string
    Email string
}

// Domain model
type User struct {
    ID    int
    Name  string
    Email string
}

// DTO for API transfer
 type UserDTO struct {
    Name  string `json:"name"`
    Email string `json:"email"`
}

// Conversion functions between models
func ToDomain(entity UserEntity) User {
    return User{ID: entity.ID, Name: entity.Name, Email: entity.Email}
}

func ToDTO(user User) UserDTO {
    return UserDTO{Name: user.Name, Email: user.Email}
}

Thus, each layer works with its own model, and conversions ensure architecture purity and layer independence.