You need to convert the code to an expression tree.
using System;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
namespace WindowsFormsApplication1
{
static class Program
{
[STAThread]
static void Main()
{
using (var context = new NorthwindEntities())
{
IQueryable<Customer> query = context.Customers;
query = Simplified<Customer>(query, "CustomerID", "ALFKI");
var list = query.ToList();
}
}
static IQueryable<T> Simplified<T>(IQueryable<T> query, string propertyName, string propertyValue)
{
PropertyInfo propertyInfo = typeof(T).GetProperty(propertyName);
return Simplified<T>(query, propertyInfo, propertyValue);
}
static IQueryable<T> Simplified<T>(IQueryable<T> query, PropertyInfo propertyInfo, string propertyValue)
{
ParameterExpression e = Expression.Parameter(typeof(T), "e");
MemberExpression m = Expression.MakeMemberAccess(e, propertyInfo);
ConstantExpression c = Expression.Constant(propertyValue, propertyValue.GetType());
BinaryExpression b = Expression.Equal(m, c);
Expression<Func<T, bool>> lambda = Expression.Lambda<Func<T, bool>>(b, e);
return query.Where(lambda);
}
}
}