我可以选择在运行时关闭JsonIgnore属性吗？

Question

我正在从一组类中使用Newtonsoft.Json创建一个JSON文件.创建的文件非常大,所以我JsonProperty为属性创建了s来减小大小,JsonIgnore并为某些数据类型添加和自定义格式.

结果是从24MB减少到1MB,这很好; 但是,我希望选择在运行时生成完整版本或简化属性版本.

无论如何,我可以让序列化器可选地使用属性吗？

Answer 1

是的,这可以使用自定义完成ContractResolver.

你没有显示任何代码,所以我只是举个例子.假设我有一个Foo如下所示的课程.我想要序列化输出中的Id和Name属性,但我绝对不感兴趣AlternateName和Color.我用那些标记了[JsonIgnore].我想要出现描述,但有时这可能会变得很长,所以我使用自定义JsonConverter来限制它的长度.我还想使用更短的属性名称来描述,所以我用它标记了它[JsonProperty("Desc")].

class Foo
{
    public int Id { get; set; }
    public string Name { get; set; }
    [JsonIgnore]
    public string AlternateName { get; set; }
    [JsonProperty("Desc")]
    [JsonConverter(typeof(StringTruncatingConverter))]
    public string Description { get; set; }
    [JsonIgnore]
    public string Color { get; set; }
}

当我序列化上面的一个实例时......

Foo foo = new Foo
{
    Id = 1,
    Name = "Thing 1",
    AlternateName = "The First Thing",
    Description = "This is some lengthy text describing Thing 1 which you'll no doubt find very interesting and useful.",
    Color = "Yellow"
};

string json = JsonConvert.SerializeObject(foo, Formatting.Indented);

...我得到这个输出:

{
  "Id": 1,
  "Name": "Thing 1",
  "Desc": "This is some lengthy text describing Thing 1 "
}

现在,让我们说我有时想要获得完整的JSON输出,忽略我的自定义.我可以使用自定义ContractResolver以编程方式"取消应用"类中的属性.这是解析器的代码:

class IgnoreJsonAttributesResolver : DefaultContractResolver
{
    protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
    {
        IList<JsonProperty> props = base.CreateProperties(type, memberSerialization);
        foreach (var prop in props)
        {
            prop.Ignored = false;   // Ignore [JsonIgnore]
            prop.Converter = null;  // Ignore [JsonConverter]
            prop.PropertyName = prop.UnderlyingName;  // restore original property name
        }
        return props;
    }
}

要使用解析器,我将其添加到JsonSerializerSettings并将设置传递给序列化器,如下所示:

JsonSerializerSettings settings = new JsonSerializerSettings();
settings.ContractResolver = new IgnoreJsonAttributesResolver();
settings.Formatting = Formatting.Indented;

string json = JsonConvert.SerializeObject(foo, settings);

输出现在包括被忽略的属性,并且描述不再被截断:

{
  "Id": 1,
  "Name": "Thing 1",
  "AlternateName": "The First Thing",
  "Description": "This is some lengthy text describing Thing 1 which you'll no doubt find very interesting and useful.",
  "Color": "Yellow"
}

这里有完整的演示:https://dotnetfiddle.net/WZpeWt