from: http://shigengyu.com/wp/2014/04/propertyinfo-selector-using-lambda-expressions/

PropertySelector.cs

namespace Utility
{
  using System;
  using System.Linq.Expressions;
  using System.Reflection;

  public static class PropertySelector
  {
    public static PropertyInfo GetPropertyInfo<T>(this T obj, Expression<Func<T, object>> selector)
    {
      if (selector.NodeType != ExpressionType.Lambda)
      {
        throw new ArgumentException("Selector must be lambda expression", "selector");
      }

      var lambda = (LambdaExpression)selector;
      var memberExpression = ExtractMemberExpression(lambda.Body);

      if (memberExpression == null)
      {
        throw new ArgumentException("Selector must be member access expression", "selector");
      }

      if (memberExpression.Member.DeclaringType == null)
      {
        throw new InvalidOperationException("Property does not have declaring type");
      }

      return memberExpression.Member.DeclaringType.GetProperty(memberExpression.Member.Name);
    }

    private static MemberExpression ExtractMemberExpression(Expression expression)
    {
      if (expression.NodeType == ExpressionType.MemberAccess)
      {
        return (MemberExpression)expression;
      }

      if (expression.NodeType == ExpressionType.Convert)
      {
        var operand = ((UnaryExpression)expression).Operand;
        return ExtractMemberExpression(operand);
      }

      return null;
    }
  }
}