Json.net将属性添加到包含特定类型的

我想为DateTime类型的每个属性向json添加一个属性

我有一个自定义转换器，并在CreateProperties上有一个覆盖（见下文）。调试时，返回的属性列表包含新值，但当json到达浏览器时，它不包含新属性

    protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
    {
        var properties = base.CreateProperties(type, memberSerialization);

        foreach(var prop in base.CreateProperties(type, memberSerialization))
        {
            if(prop != null
                && (prop.PropertyType == typeof(DateTime) || prop.PropertyType == typeof(DateTime?)))
            {
                properties.Add(new JsonProperty() {
                    PropertyName = String.Format("{0}$$type", prop.PropertyName),
                    PropertyType = typeof(String)
                });
            }
        }
        return properties;
    }

受保护的重写IList CreateProperties（类型类型，MemberSerialization MemberSerialization）
{
var properties=base.CreateProperties（类型、成员序列化）；
foreach（base.CreateProperties中的var prop（类型、成员序列化））
{
if（prop！=null
&&（prop.PropertyType==typeof（DateTime）| | prop.PropertyType==typeof（DateTime？）
{
添加（新的JsonProperty（）{
PropertyName=String.Format（“{0}$$type”，prop.PropertyName），
PropertyType=typeof（字符串）
});
}
}
归还财产；
}

首先想到的是，新的Json属性随后会被删除，因为它们是无效的。可能是因为它们没有值，但是我看不到在这里设置值的方法

---

任何想法都是非常受欢迎的

您正试图通过。您的问题是没有完全初始化的所需值。至少您必须初始化

• 和。你已经在这样做了
• 至

  true

  和

  false

• 返回要在JSON中看到的序列化对象的值

此外，建议初始化：

• 返回空属性集合的自定义实现
• ，然后去做一些似是而非的事

下面将添加一个固定字符串属性，其值为“DateTime”：

生成了以下JSON：

{
  "NotADate": "a value",
  "ADate": "2017-04-23T14:25:43.511-04:00",
  "AnotherDate": "2017-04-23T14:25:43.511-04:00",
  "ADate$$type": "DateTime",
  "AnotherDate$$type": "DateTime"
}

它还可以基于某些其他属性创建合成属性。例如，以下内容为模型中的每个

DateTime

属性添加了

Date

属性：

public class AddDateFromDateTimeContractResolver : DefaultContractResolver
{
    protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
    {
        var properties = base.CreateProperties(type, memberSerialization);
        for (int i = 0, n = properties.Count; i < n; i++)
        {
            var prop = properties[i];
            if (prop.PropertyType == typeof(DateTime) || prop.PropertyType == typeof(DateTime?))
            {
                var name = string.Format("{0}$$date", prop.PropertyName);
                var newProp = new JsonProperty
                {
                    DeclaringType = type,
                    PropertyName = name,
                    UnderlyingName = name,
                    PropertyType = prop.PropertyType,
                    ValueProvider = new DateTimeToDateValueProvider(prop.ValueProvider),
                    AttributeProvider = NoAttributeProvider.Instance,
                    Readable = true,
                    Writable = false,
                    // Ensure PreserveReferencesHandling and TypeNameHandling do not apply to the synthetic property.
                    ItemIsReference = false,
                    TypeNameHandling = TypeNameHandling.None,
                };
                properties.Add(newProp);
            }
        }

        return properties;
    }
}

public class DateTimeToDateValueProvider : ValueProviderDecorator
{
    public DateTimeToDateValueProvider(IValueProvider baseProvider) : base(baseProvider) { }

    public override object GetValue(object target)
    {
        var baseValue = base.GetValue(target);
        if (baseValue is DateTime)
        {
            return ((DateTime)baseValue).Date;
        }
        return baseValue;
    }

    public override void SetValue(object target, object value)
    {
        throw new NotImplementedException();
    }
}

public abstract class ValueProviderDecorator : IValueProvider
{
    readonly IValueProvider baseProvider;

    public ValueProviderDecorator(IValueProvider baseProvider)
    {
        if (baseProvider == null)
            throw new ArgumentNullException();
        this.baseProvider = baseProvider;
    }

    public virtual object GetValue(object target) { return baseProvider.GetValue(target); }

    public virtual void SetValue(object target, object value) { baseProvider.SetValue(target, value); }
}

---

演示两个合同解析程序的示例。

您需要初始化

JsonProperty

的所有属性，尤其是

值提供程序

。这里有一个例子：或。请分享一个你想要返回的JSON的例子，这样我们就可以完全回答你的问题。这正是我想要的。非常感谢你的帮助

{
  "NotADate": "a value",
  "ADate": "2017-04-23T14:25:43.511-04:00",
  "AnotherDate": "2017-04-23T14:25:43.511-04:00",
  "ADate$$type": "DateTime",
  "AnotherDate$$type": "DateTime"
}

public class AddDateFromDateTimeContractResolver : DefaultContractResolver
{
    protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
    {
        var properties = base.CreateProperties(type, memberSerialization);
        for (int i = 0, n = properties.Count; i < n; i++)
        {
            var prop = properties[i];
            if (prop.PropertyType == typeof(DateTime) || prop.PropertyType == typeof(DateTime?))
            {
                var name = string.Format("{0}$$date", prop.PropertyName);
                var newProp = new JsonProperty
                {
                    DeclaringType = type,
                    PropertyName = name,
                    UnderlyingName = name,
                    PropertyType = prop.PropertyType,
                    ValueProvider = new DateTimeToDateValueProvider(prop.ValueProvider),
                    AttributeProvider = NoAttributeProvider.Instance,
                    Readable = true,
                    Writable = false,
                    // Ensure PreserveReferencesHandling and TypeNameHandling do not apply to the synthetic property.
                    ItemIsReference = false,
                    TypeNameHandling = TypeNameHandling.None,
                };
                properties.Add(newProp);
            }
        }

        return properties;
    }
}

public class DateTimeToDateValueProvider : ValueProviderDecorator
{
    public DateTimeToDateValueProvider(IValueProvider baseProvider) : base(baseProvider) { }

    public override object GetValue(object target)
    {
        var baseValue = base.GetValue(target);
        if (baseValue is DateTime)
        {
            return ((DateTime)baseValue).Date;
        }
        return baseValue;
    }

    public override void SetValue(object target, object value)
    {
        throw new NotImplementedException();
    }
}

public abstract class ValueProviderDecorator : IValueProvider
{
    readonly IValueProvider baseProvider;

    public ValueProviderDecorator(IValueProvider baseProvider)
    {
        if (baseProvider == null)
            throw new ArgumentNullException();
        this.baseProvider = baseProvider;
    }

    public virtual object GetValue(object target) { return baseProvider.GetValue(target); }

    public virtual void SetValue(object target, object value) { baseProvider.SetValue(target, value); }
}

{
  "NotADate": "a value",
  "ADate": "2017-04-23T14:25:43.511-04:00",
  "AnotherDate": "2017-04-23T14:25:43.511-04:00",
  "ADate$$date": "2017-04-23T00:00:00-04:00",
  "AnotherDate$$date": "2017-04-23T00:00:00-04:00"
}