我怎样才能让DataContractJsonSerializer序列化一个对象作为一个字符串？ [英] How can I make DataContractJsonSerializer serialize an object as a string?

问题描述

我在C＃中，它包装一个GUID的结构。我使用DataContractJsonSerializer序列化包含类的实例对象。当我是直接使用GUID，它是序列化作为一个普通的字符串，但现在它的序列化为一个名称/值对。这里有一个NUnit测试和支持code演示该问题：

I have a struct in C# that wraps a guid. I'm using DataContractJsonSerializer to serialize an object containing an instance of that class. When I was using a guid directly, it was serialized as a plain string, but now it's serialized as a name/value pair. Here's an NUnit test and supporting code that demonstrates the problem:

	private static string ToJson<T>(T data)
	{
		DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof (T));

		using (MemoryStream ms = new MemoryStream())
		{
			serializer.WriteObject(ms, data);
			return Encoding.Default.GetString(ms.ToArray());
		}
	}

	[Serializable]
	private class ID
	{
		private Guid _value;

		public static explicit operator ID(Guid id)
		{
			return new ID { _value = id };
		}

		public static explicit operator Guid(ID id)
		{
			return id._value;
		}
	}

	[Test]
	public void IDShouldSerializeLikeGuid()
	{
		Guid guid = Guid.NewGuid();
		ID id = (ID) guid;
		Assert.That(ToJson(id), Is.EqualTo(ToJson(guid)));
	}

和测试运行的输出：

NUnit.Framework.AssertionException:   Expected string length 38 but was 49. Strings differ at index 0.
  Expected: ""7511fb9f-3515-4e95-9a04-06580753527d""
  But was:  "{"_value":"7511fb9f-3515-4e95-9a04-06580753527d"}"
  -----------^

如何序列化我的结构作为一个普通的字符串，让我测试过？

How do I serialize my struct as a plain string and make my test pass?

推荐答案

在这种情况下，它看起来像你真的不希望JSON，你想要一个字符串，再presentation。在这种情况下，我会创建这样一个接口：

In this case it looks like you don't really want JSON, you want a string representation. In that case I would create an interface like this:

interface IStringSerialized
{
    String GetString();
}

实现你的 ID 键入此接口（和所有其他类型的有类似的要求）。

Implement this interface on your ID type (and all other types that have similar requirements).

[Serializable]
class ID : IStringSerialized
{
    private Guid _value;

    public static explicit operator ID(Guid id)
    {
    	return new ID { _value = id };
    }

    public static explicit operator Guid(ID id)
    {
    	return id._value;
    }

    public string GetString()
    {
    	return this._value.ToString();
    }
}

然后修改您的序列化的方法来处理这​​些特殊情况：

Then modify your serialization method to handle these special cases:

private static string ToJson<T>(T data)
{
	IStringSerialized s = data as IStringSerialized;

	if (s != null)
		return s.GetString();

	DataContractJsonSerializer serializer 
                = new DataContractJsonSerializer(typeof(T));

	using (MemoryStream ms = new MemoryStream())
	{
		serializer.WriteObject(ms, data);
		return Encoding.Default.GetString(ms.ToArray());
	}
}

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