How to get the PropertyInfo of a specific property?

tenpn_11801 0
Viewed 72020

I want to get the PropertyInfo for a specific property. I could use:

foreach(PropertyInfo p in typeof(MyObject).GetProperties())
{
    if ( p.Name == "MyProperty") { return p }
}

But there must be a way to do something similar to 

typeof(MyProperty) as PropertyInfo

Is there? Or am I stuck doing a type-unsafe string comparison?

Cheers.

reflection c#
5 Answers

There is a .NET 3.5 way with lambdas/Expression that doesn't use strings...

using System;
using System.Linq.Expressions;
using System.Reflection;

class Foo
{
    public string Bar { get; set; }
}
static class Program
{
    static void Main()
    {
        PropertyInfo prop = PropertyHelper<Foo>.GetProperty(x => x.Bar);
    }
}
public static class PropertyHelper<T>
{
    public static PropertyInfo GetProperty<TValue>(
        Expression<Func<T, TValue>> selector)
    {
        Expression body = selector;
        if (body is LambdaExpression)
        {
            body = ((LambdaExpression)body).Body;
        }
        switch (body.NodeType)
        {
            case ExpressionType.MemberAccess:
                return (PropertyInfo)((MemberExpression)body).Member;
            default:
                throw new InvalidOperationException();
        }
    }
}
Marc_Gravell_233540

You can do this:

typeof(MyObject).GetProperty("MyProperty")

However, since C# doesn't have a "symbol" type, there's nothing that will help you avoid using string. Why do you call this type-unsafe, by the way?

Vojislav_Stojkovic_580990

Reflection is used for runtime type evaluation. So your string constants cannot be verified at compile time.

Darin_294070

This is probably the best way:

public static class TypeExtensions
    {
        public static PropertyInfo? GetProperty<T, TValue>(this T type, Expression<Func<T, TValue>> selector) where T : class
        {
            Expression expression = selector.Body;

            return expression.NodeType == ExpressionType.MemberAccess ? (PropertyInfo)((MemberExpression)expression).Member : null;
        }
    }
user_105985340
Related