Linq Expressions does not find a public method... :-/
I write a expression that will test if a property(enum) of a object have, or have not some flags set.
The code bellow test if the validity of an object "contains" or not Monday, using the HasFlag function of an Enum.
Actually, the Call method seems do not find a corresponding "HasFlag"... What I do wrong in 开发者_JAVA百科the bellow code?
using System;
using System.Linq.Expressions;
namespace ConsoleApplication3
{
class Program
{
static void Main(string[] args)
{
Expression exp = null;
var myValParam = Expression.Parameter(typeof(TestHehe), "val");
var myValTestValidityParam = Expression.Property(myValParam, "TestValidity");
Validity myVal = Validity.Monday;
// Gives 'True'
Console.WriteLine(myVal.HasFlag(myVal));
// test it
var myConst = Expression.Constant(myVal, myVal.GetType());
// here!!!!!!!!!!!!!!!!!!!!!!!!!!
exp = Expression.Call(myValTestValidityParam, "HasFlag", null, myConst);
// No method 'HasFlag' on type 'ConsoleApplication3.Validity'
// is compatible with the supplied arguments.
// just to be
Console.WriteLine(exp.ToString());
}
}
public class TestHehe
{
public Validity TestValidity { get; set; }
}
[Flags]
public enum Validity
{
Monday = 0,
Tuesday = 1,
Wednesday = 2,
Thursday = 4,
Friday = 8,
Saturday = 16,
Sunday = 32
}
}
var myConst = Expression.Constant(myVal, typeof(Enum));
// here!
exp = Expression.Call(myValTestValidityParam, "HasFlag", null, myConst);
Are you looking for this? HasFlag
wants an Enum
as the parameter, so I downcasted myVal
.
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