Dynamic sorting with nullable column - linq

Question

I am writing dynamic sorting with lambda expression as below:
string sortColumn = imageFilterType == 1 ? "CreatedDate" : "AbuseCount";
var paramExp = Expression.Parameter(typeof(Items), typeof(Items).ToString());
Expression propConvExp = Expression.Convert(Expression.Property(paramExp, sortColumn), typeof(object));
var sortExp = Expression.Lambda<Func<Items, object>>(propConvExp, paramExp);
Above I am creating dynamic sort column and I am applying this sortexpression in bellow query:
var items = _db.Items.AsQueryable()
.AsExpandable()
.OrderByDescending(sortExp)
.Where(predicate)
.Select(x => x)
.Join(_db.Users, i => i.UserId, u => u.UserID, (i, u) => new
{
i,
FullName = u.UserType == 1 ? u.FirstName + " " + u.LastName : u.CompanyName,
u.UserType,
u.UserName
})
.ToList()
.Skip(pageIndex)
.Take(pageSize);
I have 2 columns in input by which I have to sort data one is CreatedDate and another is Abusecount. I have to apply sorting with one column among both of them. but as I am trying to run above code I am getting error:
"Unable to cast the type 'System.Nullable`1' to type 'System.Object'. LINQ to Entities only supports casting EDM primitive or enumeration types."
Since in my database both column is of nullable type thatswhy I am getting this problem. Is anyone have solution of this problem? I don't want to change in DB. I have to solve it from fron end only.

Answer 1

Try this, it's much simplier:
var items = _db.Items.AsQueryable()
.AsExpandable();
if (imageFilterType == 1)
items=items.OrderByDescending(a=>a.CreatedDate);
else
items=items.OrderByDescending(a=>a.AbuseCount);
items=items.Where(predicate)
.Select(x => x)
.Join(_db.Users, i => i.UserId, u => u.UserID, (i, u) => new
{
i,
FullName = u.UserType == 1 ? u.FirstName + " " + u.LastName : u.CompanyName,
u.UserType,
u.UserName
})
.Skip(pageIndex)
.Take(pageSize)
.ToList();