我需要将我的类转换为 JSON,我使用 Json.NET。但我可以有不同的 JSON 结构,例如:
{
name: "Name",
type: "simple1",
value: 100
};
或
{
name: "Name",
type: {
optional1: {
setting1: "s1",
setting2: "s2",
///etc.
},
value: 100
};
我的 C# 代码是:
public class Configuration
{
[JsonProperty(PropertyName = "name")]
public string Name{ get; set; }
[JsonProperty(PropertyName = "type")]
public MyEnumTypes Type { get; set; }
public OptionalType TypeAdditionalData { get; set; }
[JsonProperty(PropertyName = "value")]
public int Value { get; set; }
public bool ShouldSerializeType()
{
OptionalSettingsAttribute optionalSettingsAttr = this.Type.GetAttributeOfType<OptionalSettingsAttribute>();
return optionalSettingsAttr == null;
}
public bool ShouldSerializeTypeAdditionalData()
{
OptionalSettingsAttribute optionalSettingsAttr = this.Type.GetAttributeOfType<OptionalSettingsAttribute>();
return optionalSettingsAttr != null;
}
}
public enum MyEnumTypes
{
[EnumMember(Value = "simple1")]
Simple1,
[EnumMember(Value = "simple2")]
Simple2,
[OptionalSettingsAttribute]
[EnumMember(Value = "optional1")]
Optional1,
[EnumMember(Value = "optional2")]
[OptionalSettingsAttribute]
Optional2
}
我的想法是当 Configuration.Type
- 值没有属性 OptionalSettingsAttribute
- 将其序列化为 type: "simple1"
。否则 - 使用 Configuration.Type
- 值作为类型的值键(type: { optional1: {} }
)和 Configuration.TypeAdditionalData
中的值作为 optional1
- 值(如上面的 2 个简单 JSON)。
我尝试创建一个自定义转换器,例如:
public class ConfigurationCustomConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return typeof(Configuration).IsAssignableFrom(objectType);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
return serializer.Deserialize<Configuration>(reader);
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
//my changes here
serializer.Serialize(writer, value);
}
但是当我将 [JsonConverter(typeof(ConfigurationCustomConverter))]
属性添加到 Configuration
类时:
[JsonConverter(typeof(ConfigurationCustomConverter))]
public class Configuration
并调用了 JsonConvert.SerializeObject(configurationObj);
我收到了下一个错误:
Self referencing loop detected with type 'Configuration'. Path ''.
您是否知道如何更改我的代码以将我的类序列化为 2 种不同的 JSON 结构? 注意:我不会使用相同的类来反序列化 JSON。
谢谢!
最佳答案
您收到检测到自引用循环
异常的原因是 WriteJson
转换器的方法正在递归调用自身。当您使用 [JsonConverter(typeof(ConfigurationCustomConverter))]
将转换器应用于类型时,WriteJson()
方法将无条件地替换 Json。 NET 的默认实现。因此你的内心呼唤:
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
//my changes here
serializer.Serialize(writer, value);
}
会导致堆栈溢出。 Json.NET 注意到这一点,而是抛出您看到的异常。有关详细信息,请参阅 JSON.Net throws StackOverflowException when using [JsonConvert()] .设置 ReferenceLoopHandling.Ignore
只会导致无限递归被跳过,使您的对象为空。
您有几个选项可以解决这个问题:
您可以手动编写除
Type
和TypeAdditionalData
之外的所有属性名称和值,然后写出自定义“type”
属性最后的。例如:[JsonConverter(typeof(ConfigurationConverter))] public class Configuration { [JsonProperty(PropertyName = "name")] public string Name { get; set; } public MyEnumTypes Type { get; set; } public OptionalType TypeAdditionalData { get; set; } [JsonProperty(PropertyName = "value")] public int Value { get; set; } } class ConfigurationConverter : JsonConverter { const string typeName = "type"; public override bool CanConvert(Type objectType) { return typeof(Configuration).IsAssignableFrom(objectType); } public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer) { if (reader.TokenType == JsonToken.Null) return null; var config = (existingValue as Configuration ?? (Configuration)serializer.ContractResolver.ResolveContract(objectType).DefaultCreator()); // Populate the regular property values. var obj = JObject.Load(reader); var type = obj.RemoveProperty(typeName); using (var subReader = obj.CreateReader()) serializer.Populate(subReader, config); // Populate Type and OptionalType if (type is JValue) // Primitive value { config.Type = type.ToObject<MyEnumTypes>(serializer); } else { var dictionary = type.ToObject<Dictionary<MyEnumTypes, OptionalType>>(serializer); if (dictionary.Count > 0) { config.Type = dictionary.Keys.First(); config.TypeAdditionalData = dictionary.Values.First(); } } return config; } public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) { var config = (Configuration)value; var contract = (JsonObjectContract)serializer.ContractResolver.ResolveContract(config.GetType()); writer.WriteStartObject(); foreach (var property in contract.Properties .Where(p => p.Writable && (p.ShouldSerialize == null || p.ShouldSerialize(config)) && !p.Ignored)) { if (property.UnderlyingName == "Type" || property.UnderlyingName == "TypeAdditionalData") continue; var propertyValue = property.ValueProvider.GetValue(config); if (propertyValue == null && serializer.NullValueHandling == NullValueHandling.Ignore) continue; writer.WritePropertyName(property.PropertyName); serializer.Serialize(writer, propertyValue); } writer.WritePropertyName(typeName); if (config.Type.GetCustomAttributeOfEnum<OptionalSettingsAttribute>() == null) { serializer.Serialize(writer, config.Type); } else { var dictionary = new Dictionary<MyEnumTypes, OptionalType> { { config.Type, config.TypeAdditionalData }, }; serializer.Serialize(writer, dictionary); } writer.WriteEndObject(); } } public class OptionalType { public string setting1 { get; set; } } public class OptionalSettingsAttribute : System.Attribute { public OptionalSettingsAttribute() { } } [JsonConverter(typeof(StringEnumConverter))] public enum MyEnumTypes { [EnumMember(Value = "simple1")] Simple1, [EnumMember(Value = "simple2")] Simple2, [OptionalSettingsAttribute] [EnumMember(Value = "optional1")] Optional1, [EnumMember(Value = "optional2")] [OptionalSettingsAttribute] Optional2 } public static class EnumExtensions { public static TAttribute GetCustomAttributeOfEnum<TAttribute>(this Enum value) where TAttribute : System.Attribute { var type = value.GetType(); var memInfo = type.GetMember(value.ToString()); return memInfo[0].GetCustomAttribute<TAttribute>(); } } public static class JsonExtensions { public static JToken RemoveProperty(this JObject obj, string name) { if (obj == null) return null; var property = obj.Property(name); if (property == null) return null; var value = property.Value; property.Remove(); property.Value = null; return value; } }
请注意,我将
[JsonConverter(typeof(StringEnumConverter))]
添加到您的枚举中。这确保类型始终写为字符串。样本 fiddle .
您可以通过 JSON.Net throws StackOverflowException when using [JsonConvert()] 中所示的技术禁用对转换器的递归调用。 ,生成一个默认的序列化,根据需要修改,写出来。
您可以通过将
Type
和TypeAdditionalData
标记为[JsonIgnore]
并引入额外的私有(private)来完全避免使用转换器序列化和反序列化"type"
的属性:public class Configuration { [JsonProperty(PropertyName = "name")] public string Name { get; set; } [JsonIgnore] public MyEnumTypes Type { get; set; } [JsonIgnore] public OptionalType TypeAdditionalData { get; set; } [JsonProperty("type")] JToken SerializedType { get { if (Type.GetCustomAttributeOfEnum<OptionalSettingsAttribute>() == null) { return JToken.FromObject(Type); } else { var dictionary = new Dictionary<MyEnumTypes, OptionalType> { { Type, TypeAdditionalData }, }; return JToken.FromObject(dictionary); } } set { if (value == null || value.Type == JTokenType.Null) { TypeAdditionalData = null; Type = default(MyEnumTypes); } else if (value is JValue) { Type = value.ToObject<MyEnumTypes>(); } else { var dictionary = value.ToObject<Dictionary<MyEnumTypes, OptionalType>>(); if (dictionary.Count > 0) { Type = dictionary.Keys.First(); TypeAdditionalData = dictionary.Values.First(); } } } } [JsonProperty(PropertyName = "value")] public int Value { get; set; } }
关于c# - Json.NET不同的json结构,基于枚举值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37896661/