Two times Projection triggers LINQ expression translation exception

[ahmed-saleh101]

Hi Everyone,

I'm working on application where I have to perform the projection 2 times
1- Between EfModel and DomainModel
2-Between DomainModel and DTO

I'd like to keep the process as IQueryable all the way from the request to response, so I perfomed the following steps

1-
In Interface layer where my graphql query lands:

public async Task<IQueryable<BoxDto>> Boxes ([Service] IBoxService boxService, [Service] IMapper mapper)
 {
     //GetAll as you will see in the next step returns a DomainModel _Box_
     //We project it here to a DTO _Exactly here the exception being triggered
     return (await boxService.GetAll()).ProjectTo<BoxDto>(mapper.ConfigurationProvider);
 }

Application layer

public async Task<IQueryable<Box>> GetAll()
   {
       return await _boxRepository.GetAll();
   } 

Then the in the repository

    public async Task<IQueryable<Box>> GetAll()
    {
       //Here we project from the DBModel _Kisten_ to Box  works smoothly although it's more complex as from DomainModel to DTO
        return _dbContext.Kisten.AsNoTracking().ProjectTo<Box>(_mapper.ConfigurationProvider);
    }

If I replace the <IQueryable<BoxDto>> with <IQueryable<Box>> everything works well even with complex and nested queries, the problem is with the second projection
it worth to share that
-The BoxDTO and Box are identical, the types are of course different but the properties has the same names
-The query takes in normal case 700 ms if I return a DomainModel, while it takes 35 Seconds until the exceptions shows up
-I've tried the MaxDepth(1) as I had a doubt of circular references but with no difference

I appreciate your help!

Beste regards,
Ahmed

[ahmed-saleh101]

Sorry, incorrect repository