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;
    }
}

由于ExpandoObject继承了IDictionary<string对象>，您可以使用以下检查

dynamic myVariable = GetDataThatLooksVerySimilarButNotTheSame();

if (((IDictionary<string, object>)myVariable).ContainsKey("MyProperty"))    
//Do stuff

您可以创建一个实用程序方法来执行此检查，这将使代码更加清晰和可重用

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;

以防它能帮到别人:

如果GetDataThatLooksVerySimilarButNotTheSame()方法返回一个ExpandoObject，你也可以在检查之前将其转换为dictionary。

dynamic test = new System.Dynamic.ExpandoObject();
test.foo = "bar";

if (((IDictionary<string, object>)test).ContainsKey("foo"))
{
    Console.WriteLine(test.foo);
}

如果你控制的类型被用作动态，你不能返回一个元组而不是每个属性访问的值吗?之类的……

public class DynamicValue<T>
{
    internal DynamicValue(T value, bool exists)
    {
         Value = value;
         Exists = exists;
    }

    T Value { get; private set; }
    bool Exists { get; private set; }
}

可能是一个幼稚的实现，但如果您每次都在内部构造其中一个，并返回该值而不是实际值，那么您可以在每个属性访问上检查Exists，如果值为默认值(T)，则单击value(如果不为默认值，则不相关)。

也就是说，我可能会遗漏一些动态工作原理的知识，这可能不是一个可行的建议。

也许使用反射?

dynamic myVar = GetDataThatLooksVerySimilarButNotTheSame();
Type typeOfDynamic = myVar.GetType();
bool exist = typeOfDynamic.GetProperties().Where(p => p.Name.Equals("PropertyName")).Any();