对我来说，这是可行的:

if (IsProperty(() => DynamicObject.MyProperty))
  ; // do stuff



delegate string GetValueDelegate();

private bool IsProperty(GetValueDelegate getValueMethod)
{
    try
    {
        //we're not interesting in the return value.
        //What we need to know is whether an exception occurred or not

        var v = getValueMethod();
        return v != null;
    }
    catch (RuntimeBinderException)
    {
        return false;
    }
    catch
    {
        return true;
    }
}

我认为没有办法在不尝试访问动态变量的情况下发现动态变量是否有某个成员，除非你在c#编译器中重新实现动态绑定的处理方式。这可能包含很多猜测，因为根据c#规范，它是由实现定义的。

所以你应该尝试访问成员并捕获异常，如果它失败了:

dynamic myVariable = GetDataThatLooksVerySimilarButNotTheSame();

try
{
    var x = myVariable.MyProperty;
    // do stuff with x
}
catch (RuntimeBinderException)
{
    //  MyProperty doesn't exist
} 

如果你的用例是转换一个api响应，只携带一些字段，你可以使用这个:

var template = new { address = new { street = "" } };
var response = JsonConvert.DeserializeAnonymousType(await result.Content.ReadAsStringAsync(), template);

string street = response?.address?.street;

下面是另一种方法:

using Newtonsoft.Json.Linq;

internal class DymanicTest
{
    public static string Json = @"{
            ""AED"": 3.672825,
            ""AFN"": 56.982875,
            ""ALL"": 110.252599,
            ""AMD"": 408.222002,
            ""ANG"": 1.78704,
            ""AOA"": 98.192249,
            ""ARS"": 8.44469
}";

    public static void Run()
    {
        dynamic dynamicObject = JObject.Parse(Json);

        foreach (JProperty variable in dynamicObject)
        {
            if (variable.Name == "AMD")
            {
                var value = variable.Value;
            }
        }
    }
}

The two common solutions to this include making the call and catching the RuntimeBinderException, using reflection to check for the call, or serialising to a text format and parsing from there. The problem with exceptions is that they are very slow, because when one is constructed, the current call stack is serialised. Serialising to JSON or something analogous incurs a similar penalty. This leaves us with reflection but it only works if the underlying object is actually a POCO with real members on it. If it's a dynamic wrapper around a dictionary, a COM object, or an external web service, then reflection won't help.

另一种解决方案是使用IDynamicMetaObjectProvider获取DLR看到的成员名。在下面的例子中，我使用一个静态类(Dynamic)来测试Age字段并显示它。

class Program
{
    static void Main()
    {
        dynamic x = new ExpandoObject();

        x.Name = "Damian Powell";
        x.Age = "21 (probably)";

        if (Dynamic.HasMember(x, "Age"))
        {
            Console.WriteLine("Age={0}", x.Age);
        }
    }
}

public static class Dynamic
{
    public static bool HasMember(object dynObj, string memberName)
    {
        return GetMemberNames(dynObj).Contains(memberName);
    }

    public static IEnumerable<string> GetMemberNames(object dynObj)
    {
        var metaObjProvider = dynObj as IDynamicMetaObjectProvider;

        if (null == metaObjProvider) throw new InvalidOperationException(
            "The supplied object must be a dynamic object " +
            "(i.e. it must implement IDynamicMetaObjectProvider)"
        );

        var metaObj = metaObjProvider.GetMetaObject(
            Expression.Constant(metaObjProvider)
        );

        var memberNames = metaObj.GetDynamicMemberNames();

        return memberNames;
    }
}

对我来说，这是可行的:

if (IsProperty(() => DynamicObject.MyProperty))
  ; // do stuff



delegate string GetValueDelegate();

private bool IsProperty(GetValueDelegate getValueMethod)
{
    try
    {
        //we're not interesting in the return value.
        //What we need to know is whether an exception occurred or not

        var v = getValueMethod();
        return v != null;
    }
    catch (RuntimeBinderException)
    {
        return false;
    }
    catch
    {
        return true;
    }
}