将JSON字符反序列化为枚举

问题描述

我有一个用C#定义的枚举，将其值存储为字符，如下所示:

I have an enumeration defined with C#, where I'm storing it's values as characters, like this:

public enum CardType
{
    Artist = 'A',
    Contemporary = 'C',
    Historical = 'H',
    Musician = 'M',
    Sports = 'S',
    Writer = 'W'
}

我正在尝试使用JSON.NET反序列化，但是传入的JSON是使用CHAR值(字符串)而不是枚举的int值编写的，如下所示:

I'm attempting to deserialize using JSON.NET, but the incoming JSON was written using the CHAR value (string) instead of the int value of the enumeration, like this:

[{"CardType","A"},{"CardType", "C"}]

是否可以定义某种允许我手动将char解析为枚举值的转换器?

Is it possible to define some kind of converter that will allow me to manually parse the char to the enum value?

我尝试创建一个JsonConverter，但是不确定如何将其应用于此属性，而不应用于整个已解析的对象.这是我尝试过的:

I tried creating a JsonConverter, but am not sure how to do it, while applying it only to this property and not the whole parsed object. here's what I tried:

public class EnumerationConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        serializer.Serialize(writer, value);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
        {
            return null;
        }

        int value = serializer.Deserialize<int>(reader);
        return (CardType)value;
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType.IsSubclassOf(typeof(string));
    }
}

逻辑可能是错误的，我可以解决这个问题，但是问题是根本没有调用ReadJson().

The logic might be wrong and I can fix that but the problem is ReadJson() isn't being called at all.

CanConvert是，但是似乎每个属性都调用了它，而不仅仅是我为其定义的一个属性:

CanConvert is, but it appears to be called for every property, not just the one property I defined it for:

public class Card
{
            private CardType type;
        [JsonConverter(typeof(EnumerationConverter))]
        public CardType Type
        {
            get { return type; }
            set { type = value; }
        }
}

我确定我做错了，但是在查找有关如何在单个字段中执行此操作的文档时遇到了麻烦...

I'm sure I've done this incorrectly but am having trouble finding documentation on how to do this for a single field...

我想念什么?

推荐答案

您不需要自定义JsonConverter，您可以将内置的StringEnumConverter与 EnumMemberAttribute (来自System.Runtime.Serialization程序集).

You don't necessary need a custom JsonConverter you can use the built in StringEnumConverter with the combination of the EnumMemberAttribute (from the System.Runtime.Serialization assembly).

在没有EnumMemberAttribute的情况下，它使用的是枚举名称，例如Artist，Contemporary等，因此您需要将其更改为A，C等值.

Without the EnumMemberAttribute it uses the enum names so Artist, Contemporary, etc so you need to change the names with it to your A,C, etc value.

但这不是最好的解决方案，因为您必须重复两次值，但这是可行的:

But it is not the nicest solution because you have to repeat your values two times, but it works:

[JsonConverter(typeof(StringEnumConverter))]
public enum CardType
{
    [EnumMember(Value = "A")]
    Artist = 'A',
    [EnumMember(Value = "C")]
    Contemporary = 'C',
    [EnumMember(Value = "H")]
    Historical = 'H',
    [EnumMember(Value = "M")]
    Musician = 'M',
    [EnumMember(Value = "S")]
    Sports = 'S',
    [EnumMember(Value = "W")]
    Writer = 'W'
}

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