DDD clean architecture issue

[Neyzv]

Hi !

I've an issue with Facet while using a DDD Clean architecture, I can't make a registration of my dto because it is stored in my "Domain" project and my EFCore model is in my 'Infrastructure" project. So based on that I can't use it with out breaking DDD principle.

Do you have a solution ?

Best regards,
Neyzu

[Tim-Maes]

Hi @Neyzv

Are you talking about using Facet or GenerateDtos attribute? Could you elaborate more on your project/architecture setup?

[Neyzv]

Hi,

Sorry I was talking about using facet attribute, it isn't compatible with DDD I think...
But maybe I'm wrong idk

[anhaehne]

I think i have a simmilar problem. I would like to separate the Models (for ef core) from the Facets into two projects. What i don't want is the Facets project to reference the models project as the models project reference ef core and i want my api clients to reference the facets project without referencing ef core.

There is Generated Files Output Configuration but this won't work if you have other source code generators.

The only solution if can think of is to create a third project containing just the models but then i can't use ef core attributes anymore to specify my database model.

[Tim-Maes]

Hi,

The facets, mappings and projections are generated in the assembly where you declare your Facets, and Facet needs to know what the source is so you are coupled there. Unless Roslyn provides cross-assembly source generating (which I don't think will happen soon ), this dependency problem is a.. well problem, especially in your case. You can indeed work your way around it by creating a separate project or layer for most simple cases. I used to work my way around this in the past by using T4 templates and some file writing to a specific project folder.

Been wrapping my head around this for the past few days, and thinking about how we can solve this problem - open for suggestions and to discuss this

[anhaehne]

I've looked some more into possible solutions and i came to the conclusion that source generators are probably not the right solution here unless microsoft adds cross-assembly generation like you mentioned.

I've looked at Mapster. They solve the problem with a dotnet tool which then generates the DTOs after build.

[douglasg14b]

In this case, could the generated files not be pointed at a project as their "destination"?

// Over simplified, but the idea being to target a particular destination path
[GenerateDto(TargetDir="App.Project1/Gen/")]
public class User {
    public string Name { get; set; }
}


...

// Over in App.Project1 land in `Ger/`

public class UserDto {
    public string Name { get; set; }
}

Something along those lines? (Obv this is contrived)

---

In my case I need event DTOs that live in an eventing contracts assembly, most of these are just fragments or whole existing entities in DTO form.

Project.Features --> User Entity

Project.Eventing --> UserDto

Project.Features ---> Project.Eventing 

THis would involve generating DTOs for these entities from Project.Features into Project.Eventing

[Tim-Maes]

Hi @douglasg14b

Unfortunately, this is not supported - source generators can only generate source in the generating assembly. With some configuration, you can make the generated files appear in the solution explorer, but writing to custom folders or other assemblies is not possible, roslyn just doesn't support that. This can be achieved by leveraging T4 templates and just write file to destination though, but I'm not planning to introduce T4 in Facet.

Unless I'm missing something this is currently impossible.