如何使用反射从动态（匿名类型）对象获取属性？

Question

我知道这个主题在stackoverflow上有很多问题，但我找不到任何具体的答案来解决我的现状。

1. 我有一个动态生成的行集合。
2. 属性名称（列和列数）仅在运行时已知。
3. 我有以下代码，

// collection gets populated at run time, the type T is dynamic.
public void GenerateExcel<T>(string filename, IEnumerable<T> collection)
{
    // Since the T passed is dynamic Type I am facing issues in getting
    // the property names.
    var type = typeof(T); // the type T is an anonymous type, and thus
                          // the 'type' variable is always an Object type.
    var columns = type.GetProperties().Length; // when I run this line it
                                               // is obvious the properties 
                                               // returned is always 0 so how
                                               // do I get the properties?

    /* Implementation omitted */
}

1. 我使用下面的代码调用上述方法

GenerateExcel<dynamic>(
 "filename.xls",
 new[] { 
  new { Obj1 = "a", Obj2 = 1, Obj3 = 3.1, Obj4 = new DateTime(2014, 1, 1) }, 
  new { Obj1 = "b", Obj2 = 2, Obj3 = 3.2, Obj4 = new DateTime(2014, 1, 2) },
  new { Obj1 = "c", Obj2 = 3, Obj3 = 3.3, Obj4 = new DateTime(2014, 1, 3) },
  new { Obj1 = "d", Obj2 = 4, Obj3 = 3.4, Obj4 = new DateTime(2014, 1, 4) },
 }); // these objects (Obj1, Obj2 ... (columns) are generated dynamically at run time).

同样的问题被多次询问，这里是stackoverflow，但解决方案只有在您知道属性名称时才会出现，例如

1. Get property value from C# dynamic object by string (reflection?)
2. How to access property of anonymous type in C#? //只有在提前知道属性名称时才能访问该属性。

非常感谢任何帮助！

Answer 1

获取第一个项目，将其转换为 object ，然后您可以获取属性：

object e = collection.FirstOrDefault();
var columns = e.GetType().GetProperties().Length;

或者只是：

collection.FirstOrDefault().GetType().GetProperties().Length;

Answer 2

你能用吗？

 dynamic dy = obj;
 Console.WriteLine(dy.param);