Get result function in LINQ without translate to store expression

Question

I need to get result from a function that it need to run in LINQ query. This result bind to grid but in run time I encounter with this error:

LINQ to

Answer 1

GetName couldn't be translated to T-SQL, Linq to Entities couldn't recognize it. You can modify the code as below:

 var result = (from x in Data().AsEnumerable()
              select new
              {
                  Rah_CapacityId = x.Rah_CapacityId,
                  Rah_CapacityName = x.Rah_CapacityName,
                  Rah_St = Enum.GetName(typeof(Domain.Enums.CapacityState), x.Rah_St),
                  Rah_LinesId = x.Rah_LinesId
              }).OrderByDescending(o => new { o.Rah_CapacityId });

With .ToList() after data is loaded, any further operation (such as select) is performed using Linq to Objects, on the data already in memory.

EDIT: Also your method's return type is IQueryable while your query is IOrderedEnumerable of anonymous type, so you should either change the method's type to System.Object or as a better solution create a class, send the values into the class's properties, and then return it.

Answer 2

You can't use this method in Linq-To-Entities because LINQ does not know how to translate Enum.GetName to sql. So execute it in memory with Linq-To-Objects by using AsEnumerable and after the query use AsQueryable to get the desired AsQueryable:

So either:

var result = Data()
             .OrderBy(x=> x.CapacityId)
             .AsEnumerable()
             .Select(x => new
             {
                  Rah_CapacityId = x.Rah_CapacityId,
                  Rah_CapacityName = x.Rah_CapacityName,
                  Rah_St = Enum.GetName(typeof(Domain.Enums.CapacityState), x.Rah_St),
                  Rah_LinesId = x.Rah_LinesId
             })
             .AsQueryable();

You should first use OrderBy before you use AsEnumerable to benefit from database sorting performance. The same applies to Where, always do this before AsEnumerable(or ToList).