我如何添加一个类型约束，包括在一个通用的方法序列化的东西？ [英] How can I add a type constraint to include anything serializable in a generic method?

问题描述

我的泛型方法需要序列传递给它的对象，但只是坚持认为它实现了ISerializable似乎并没有工作。例如，我有一个结构的序列化为xml就好了一个Web服务（标有Seri​​alizableAttribute）返回，但是，正如预期的那样，C＃编译器抱怨。

My generic method needs to serialize the object passed to it, however just insisting that it implements ISerializable doesn't seem to work. For example, I have a struct returned from a web service (marked with SerializableAttribute) that serializes to xml just fine, but, as expected, the C# compiler complains.

有没有一种方法，我可以检查对象序列化之前试图序列，或者更好的是，使用其中，关键字来检查对象的一种方式适合呢？

Is there a way I can check the object is serializable before attempting to serialize it, or, better still, a way of using the where keyword to check the object is suitable?

下面是我完整的方法：

public static void Push<T>(string url, T message)
        where T : ISerializable
{
    string xml = SerializeMessage(message);

    // Send the message to Amazon SQS
    SendMessageRequest sendReq = new SendMessageRequest { QueueUrl = url, MessageBody = xml };
    AmazonSQSClient client = new AmazonSQSClient(S3User, S3Pass);
    client.SendMessage(sendReq);
}

和SerializeMessage：

And SerializeMessage:

private static string SerializeMessage<T>(T message)
{
    XmlSerializer xmlSerializer = new XmlSerializer(typeof(T));
    using (StringWriter stringWriter = new StringWriter())
    {
        xmlSerializer.Serialize(stringWriter, message);
        return stringWriter.ToString();
    }
}

如果这是不可能的，什么是执行检查的最佳方法，一个对象在运行时是可序列化

If this isn't possible, what's the best way to perform a check that an object is serializable at runtime?

推荐答案

您不能这样做完全通过通用的限制，但你可以做几件事情，以帮助：

You can't do this totally via generic constraints, but you can do a couple things to help:

1）把对泛型类型在新（）约束（以使反序列化的能力，并确保XmlSerializer的不抱怨缺少默认构造函数中）：

1) Put the new() constraint on the generic type (to enable the ability to deserialize and to ensure the XmlSerializer doesn't complain about a lack of default ctor):

where T : new()

2）你的方法处理序列化（或构造函数或其他任何地方，你不必一遍遍重复）的第一行，然后才能执行此检查：

2) On the first line of your method handling the serialization (or constructor or anywhere else you don't have to repeat it over and over), you can perform this check:

if( !typeof(T).IsSerializable && !(typeof(ISerializable).IsAssignableFrom(typeof(T)) ) )
    throw new InvalidOperationException("A serializable Type is required");

当然，还是有试图序列化类型时，运行时异常的可能性，但是这将覆盖最明显的问题。

Of course, there's still the possibility of runtime exceptions when trying to serialize a type, but this will cover the most obvious issues.

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