GroupBy automapper aggregation

Question

I'm trying to map my entity into a new structure.

My entity looks like:

public class Settings
    {
        public int Id { get; protected set; }
        public int UserId { get; set; }
        string string Property{ get; set; }
        public string Element { get; set; }
        public string Value { get; set; }

    }

So from database would come something like (where value is some json based value)

UserId      Property   Element  Value
----------- ---------- -------- ------
15          std1       grid     [...]
15          std1       panel    [...]
15          std2       panel    [...]
15          std2       grid     [...]
15          std4       panel    [...]
15          std5       panel    [...]
15          std12      grid     [...]

My goal is to output something structured like:

{
    "std1": {
        "Elements": {
            "grid": "[...]",
            "panel": "[...]"
        }
    },
    "std2": {
        "Elements": {
            "grid":  "[...]",
            "panel": "[...]"
        }
    },
    "std4": {
        "Elements": {
            "panel": "[...]"
        }
    },
    ...
}

I created the folling DTO's to achieve this:

public class SettingsToReturnDto
    {
        public string Domain { get; set; }
        public List<ElementsToReturnDto> Elements { get; set; }
    }

    public class ElementsToReturnDto
    {
        public string Element { get; set; }
        public string Value { get; set; }
    }
}

I tried to use a automapper mapping to achieve this, but all my attemps failed into convert into the new structure

can you point me into the correct direction? thanks

Answer 1

Here is the working demo , you could refer to

SettingsProfile

public class SettingsProfile:Profile
{
    public SettingsProfile()
    {
        CreateMap<IGrouping<string, Settings>, SettingsToReturnDto>()
            .ForMember(dest => dest.Domain, opt => opt.MapFrom(src => src.Key))
            .ForMember(dest => dest.Elements, opt => opt.MapFrom(src => src.ToList()));
        CreateMap<Settings, ElementsToReturnDto>();
    }
}

Controller

public class ValuesController : ControllerBase
{
    private readonly SeeMiddleContext _context;
    private readonly IMapper _mapper;

    public ValuesController(SeeMiddleContext context, IMapper mapper)
    {
        _context = context;
        _mapper = mapper;
    }

    public IActionResult GetSettings()
    {
        List <IGrouping<string, Settings>> settingsFromDB = _context.Settings.GroupBy(s=>s.Property).ToList();

        var settingsToReturn = _mapper.Map<List<IGrouping<string, Settings>>,List<SettingsToReturnDto>>(settingsFromDB);

        return new JsonResult(settingsToReturn); 
    }
}