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目前的情况.

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 */
}

4. 我用下面的代码调用上面的方法,

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).
);

多次询问相同的问题,例如stackoverflow,但解决方案仅在您知道属性名称时才会出现

1. 从字符串中获取C#动态对象的属性值(反射？)
2. 如何在C#中访问匿名类型的属性？//只有在事先知道属性名称时才能访问该属性.

任何帮助是极大的赞赏!

Answer 1

获取第一个项目,将其强制转换为对象,然后您可以获取属性:

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

要不就:

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