Question

我在C＃中有一个dynamic对象，我想转换为静态对象。我写了一个函数，它接受动态类型并返回静态类型，但它实际返回dynamic，忽略指定的返回类型。（这是标准行为，正如我现在发现的那样。）AutoMapper不处理dynamic类型。如何正确地将dynamic转换为静态？

Answer 1

使用某些序列化程序可以解决问题。假设您形成一个动态对象，如

dynamic d = new ExpandoObject();
d.a = 1;
d.b = new ExpandoObject();
d.b.c = "222";

并且您希望将其转换为A

public class A
{
    public int a { set; get; }
    public B   b { set; get; }
}

public class B
{
    public string c { set; get; }
}

您可以使用Json.Net来执行此序列化/反序列化

A a = JsonConvert.DeserializeObject<A>(JsonConvert.SerializeObject(d));

Answer 2

如果您获得了类型，则可以实例化一个新对象，然后使用FormatterServices类将动态对象的状态复制到此对象中：

var staticObject = Activator.CreateInstance(yourType);
MemberInfo[] members = FormatterServices.GetSerializableMembers(yourType);
FormatterServices.PopulateObjectMembers(staticObject, members, 
  FormatterServices.GetObjectData(dynObject, members));

Answer 3

我很困惑......我认为.NET应该已经为你做了这件事。这是一些测试代码，符合我的期望：

class Program
{
    static void Main(string[] args)
    {
        dynamic anythingGoes = 1;
        var convertedToInt = ConvertToType<int>(anythingGoes);

        // expectation: should output Int32. and it does....
        Console.WriteLine(convertedToInt.GetType().Name);


        anythingGoes = "ribbit";
        var convertedToString = ConvertToType<string>(anythingGoes);

        // expectation: should output String. and it does also...
        Console.WriteLine(convertedToString.GetType().Name);

        Console.ReadLine();
    }

    // just a small method to cast the dynamic to whatever i want
    // ...only for this test. not guaranteed to be crash safe. in fact, don't assume!
    static T ConvertToType<T>(dynamic obj)
    {
        T result = obj;
        return result;
    }
}

正确地将动态转换为静态

3 个答案: