How to specify dynamic field names in a Linq where clause?

Question

If you create a Filter object that contains criteria for Linq that normally goes in a where clause like this:

 var myFilterObject = FilterFactory.GetBlank();         


        

Answer 1

You can build the Expression by hand, like so:

var eParam = Expression.Parameter(typeof(Employee), "e");

var comparison = Expression.Lambda(
    Expression.LessThan(
        Expression.Property(eParam, "Salary"),
        Expression.Constant(40000)),
    eParam);

return from e in db.Employee.Where(comparison)
       select new EmployeeViewModel { Name = e.name, Salary = e.Salary };