Linq Expression属性类型

Question

I have a linq expression defined as follows:

private void GetMyPropertyType<T>(Expression<Func<T, object>> expression)
{
    // some code
    ----- HERE -----
}

which is called as

GetMyPropertyType<SomeType>(x => x.Age);

Now I want to know what the type is of "Age" at the position marked as "HERE". The closest I've gotten is:"

expression.Body.Member.ToString()

which returns the value Int64 Age that I can then split and only take the first part of. The problem however is that I want to get the full path ( System.Int64 ) which it only returns for certain types (like String ). Am I missing a completely obvious method? Or should I be doing it in this very ugly fashion?

Thanks in advance for any help.

Answer 1

You can use Expression.Type to find out the static type of the expression. However, because you've got Expression<Func<T, object>> you've actually got a conversion expression around the property expression, so you need to remove that first. Here's some sample code which works for the simple cases I've tried:

using System;
using System.Linq.Expressions;

class Person
{
    public int Age { get; set; }
    public string Name { get; set; }
}

class Test
{
    static void Main(string[] args)
    {
        ShowMemberType<Person>(p => p.Age);
        ShowMemberType<Person>(p => p.Name);
    }

    static void ShowMemberType<T>(Expression<Func<T, object>> expression)
    {
        var body = expression.Body;
        // Unwrap the conversion to object, if there is one.
        if (body.NodeType == ExpressionType.Convert)
        {
            body = ((UnaryExpression)body).Operand;
        }
        Console.WriteLine("Type: {0}", body.Type);
    }
}