通过自定义属性 (json.net) 从序列化中排除属性 [英] Exclude property from serialization via custom attribute (json.net)

问题描述

我需要能够控制类上的某些属性如何/是否被序列化.最简单的情况是[ScriptIgnore].但是，我只希望在我正在处理的这种特定序列化情况下使用这些属性 - 如果应用程序下游的其他模块也想序列化这些对象，那么这些属性都不应该妨碍.

I need to be able to control how/whether certain properties on a class are serialized. The simplest case is [ScriptIgnore]. However, I only want these attributes to be honored for this one specific serialization situation I am working on - if other modules downstream in the application also want to serialize these objects, none of these attributes should get in the way.

所以我的想法是在属性上使用自定义属性 MyAttribute，并使用知道查找该属性的钩子初始化 JsonSerializer 的特定实例.

So my thought is to use a custom attribute MyAttribute on the properties, and initialize the specific instance of JsonSerializer with a hook that knows to look for that attribute.

乍一看，我没有看到 JSON.NET 中的任何可用挂钩点会为当前属性提供 PropertyInfo 以进行此类检查 - 只有属性的值.我错过了什么吗?或者有更好的方法来解决这个问题?

At first glance, I don't see any of the available hook points in JSON.NET will provide the PropertyInfo for the current property to do such an inspection - only the property's value. Am I missing something? Or a better way to approach this?

推荐答案

您有几个选择.我建议您阅读 Json.Net 文档 文章在阅读下面的内容之前.

You have a few options. I recommend you read the Json.Net documentation article on the subject before reading below.

文章介绍了两种方法:

1. 根据命名约定创建一个返回 bool 值的方法，Json.Net 将遵循该约定来确定是否序列化属性.
2. 创建一个忽略属性的自定义合同解析器.

1. Create a method that returns a bool value based on a naming convention that Json.Net will follow to determine whether or not to serialize the property.
2. Create a custom contract resolver that ignores the property.

在这两者中，我更喜欢后者.完全跳过属性——仅使用它们来忽略所有形式的序列化的属性.相反，创建一个忽略相关属性的自定义合约解析器，并且仅在您想要忽略该属性时使用合约解析器，让该类的其他用户可以自由地序列化该属性，或者不是他们自己的心血来潮.

Of the two, I favor the latter. Skip attributes altogether -- only use them to ignore properties across all forms of serialization. Instead, create a custom contract resolver that ignores the property in question, and only use the contract resolver when you want to ignore the property, leaving other users of the class free to serialize the property or not at their own whim.

编辑为了避免链接失效，我发布了文章中的相关代码

Edit To avoid link rot, I'm posting the code in question from the article

public class ShouldSerializeContractResolver : DefaultContractResolver
{
   public new static readonly ShouldSerializeContractResolver Instance =
                                 new ShouldSerializeContractResolver();

   protected override JsonProperty CreateProperty( MemberInfo member,
                                    MemberSerialization memberSerialization )
   {
      JsonProperty property = base.CreateProperty( member, memberSerialization );

      if( property.DeclaringType == typeof(Employee) &&
            property.PropertyName == "Manager" )
      {
         property.ShouldSerialize = instance =>
         {
            // replace this logic with your own, probably just  
            // return false;
            Employee e = (Employee)instance;
            return e.Manager != e;
         };
      }

      return property;
   }
}

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