实体框架在数据库中不存在的列上排序

Question

In my model I have a property that is a combination of other models.

        public string PiramideId => (string.IsNullOrWhiteSpace(GEMEENTECODE) ? "" : GEMEENTECODE.Trim()) + "-" + (string.IsNullOrWhiteSpace(WIJKCODE) ? "" : WIJKCODE.Trim()) + "-" + (string.IsNullOrWhiteSpace(GROEPCODE) ? "" : GROEPCODE.Trim()) + "-" + (string.IsNullOrWhiteSpace(STRAATCODE) ? "" : STRAATCODE.Trim()) + "-" + (string.IsNullOrWhiteSpace(GEBOUWCODE) ? "" : GEBOUWCODE.Trim()) + "-" + (string.IsNullOrWhiteSpace(HUISNR) ? "" : HUISNR.Trim());

When I do a call in Entity Framework when I try to sort on PiramideId EF returns an error saying that the column does not exist in the database. Is there a way to tell EF that the column PiramideId is basically a few sorts combined together?

I tried sorting after getting a list of all items, and even though that works it's not what I want, because then I have to get all records in my db while I only want the top 30.

Example of query:

PagedView.Context.PERSOON.Join(PagedView.Context.VERHURINGEN, persoon => persoon.ComputerNr,
                        verhuring => verhuring.PersoonsID, (persoon, verhuring) => new {persoon, verhuring})
                    .Join(PagedView.Context.EENHEID, @t => @t.verhuring.Eenheid, eenheid => eenheid.ComputerNr,
                        (@t, eenheid) => new PersoonDTO
                        {
                            ComputerNr = @t.persoon.ComputerNr,
                            FAMILIENAAM = @t.persoon.FAMILIENAAM,
                            VOORNAAM = @t.persoon.VOORNAAM,
                            NAAM = @t.persoon.NAAM,
                            ADRES = @t.persoon.ADRES,
                            Een = eenheid
                        }).OrderBy(p => p.Een.PiramideId).ToList();

Answer 1

Entity Framework works by generating a SQL statement, querying the database, then mapping the results on to the model. In this particular case it can't produce the SQL statement as it has no idea what PiramideId is. You can get round this by performing the query, then sorting. The easiest way to get it to perform the query is using AsEnumerable . This gives you

PagedView.Context.PERSOON
                 .Join(PagedView.Context.VERHURINGEN, 
                       persoon => persoon.ComputerNr,
                       verhuring => verhuring.PersoonsID,
                       (persoon, verhuring) => new {persoon, verhuring})
                 .Join(PagedView.Context.EENHEID,
                       @t => @t.verhuring.Eenheid,
                       eenheid => eenheid.ComputerNr,
                       (@t, eenheid) => new PersoonDTO
                       {
                           ComputerNr = @t.persoon.ComputerNr,
                           FAMILIENAAM = @t.persoon.FAMILIENAAM,
                           VOORNAAM = @t.persoon.VOORNAAM,
                           NAAM = @t.persoon.NAAM,
                           ADRES = @t.persoon.ADRES,
                           Een = eenheid
                       })
                 .AsEnumerable()
                 .OrderBy(p => p.Een.PiramideId)
                 .ToList();