使用JSON.NET序列化对象时，如何添加自定义根节点? [英] How can I add a custom root node when serializing an object with JSON.NET?

问题描述

我已经向某些对象添加了自定义属性，如下所示:

I have added a custom property to some of my objects like this:

[JsonCustomRoot("status")]
public class StatusDTO 
{
    public int StatusId { get; set; }
    public string Name { get; set; }
    public DateTime Created { get; set; }
}

该属性非常简单:

public class JsonCustomRoot :Attribute
{
    public string rootName { get; set; }

    public JsonCustomRoot(string rootName)
    {
        this.rootName = rootName;
    }
}

序列化对象实例时，JSON.NET的默认输出是:

The default output from JSON.NET when serializing an instance of an object is this:

{"StatusId":70,"Name":"Closed","Created":"2012-12-12T11:50:56.6207193Z"}

现在的问题是:如何使用自定义属性的值向JSON添加根节点:

{status:{"StatusId":70,"Name":"Closed","Created":"2012-12-12T11:50:56.6207193Z"}}

我发现有几篇文章提到 IContractResolver 界面，但我不知道该怎么做.我的尝试包括这段未完成的代码:

I have found several articles mentioning the IContractResolver interface, but I cannot grasp how to do it. My attempts include this unfinished piece of code:

protected override JsonObjectContract CreateObjectContract(Type objectType)
{
    JsonObjectContract contract = base.CreateObjectContract(objectType);

    var info = objectType.GetCustomAttributes()
                   .SingleOrDefault(t => (Type)t.TypeId==typeof(JsonCustomRoot));
    if (info != null)
    {
        var myAttribute = (JsonCustomRoot)info;
        // How can i add myAttribute.rootName to the root from here?
        // Maybe some other method should be overrided instead?
    }

    return contract;
}

推荐答案

这是专门针对Web API的解决方案，我也在使用: RootFormatter .cs

Here's a solution specifically for Web API, which I am also using: RootFormatter.cs

我基于我没有使用自定义属性，而是重用了JsonObjectAttribute的标题"字段.这是一个用法代码:

Instead of using a custom attribute I am reusing Title field of JsonObjectAttribute. Here's a usage code:

using Newtonsoft.Json

[JsonObject(Title = "user")]
public class User
{
    public string mail { get; set; }
}

然后，将RootFormatter添加到您的App_Start中，并在WebApiConfig中进行如下注册:

Then, add RootFormatter to your App_Start and register it as follows in WebApiConfig:

GlobalConfiguration.Configuration.Formatters.Insert(0, new RootFormatter());

我能够得到类似于WCF WebMessageBodyStyle.Wrapped的包装响应:

I was able to get a wrapped response similar to WCF's WebMessageBodyStyle.Wrapped:

{"user":{
  "mail": "[e-mail]"
}}

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