使用 Json.Net 反序列化时支持多种自定义 DateTime 格式

问题描述

我想支持使用 Newtonsoft Json 反序列化器反序列化多个自定义 DateTime 格式，所以我使用 IsoDateTimeConverter:

I want to support deserializing more than one custom DateTime format with the Newtonsoft Json deserializer, so I am using IsoDateTimeConverter:

var serializeSettings = new JsonSerializerSettings();
serializeSettings.Converters.Add(new IsoDateTimeConverter() { DateTimeFormat = "yyyyMMddTHHmmssZ" });

由于 DateTimeFormat 属性不接受格式数组，我尝试了以下方法来支持多种自定义日期格式:

As the DateTimeFormat property does not accept an array of formats, I tried the following to support multiple custom date formats:

var serializeSettings = new JsonSerializerSettings();
serializeSettings.Converters.Add(new IsoDateTimeConverter() { DateTimeFormat = "yyyyMMddTHHmmssZ" });
serializeSettings.Converters.Add(new IsoDateTimeConverter() { DateTimeFormat = "yyyy-MM-ddTHH:mm" });

但是上面的代码结果只支持反序列化第一种格式.

However the above code's result is supporting deserializing only the first format.

如何实现对多种自定义 DateTime 格式的支持?

How can I achieve supporting multiple custom DateTime formats?

推荐答案

如果您想处理多种可能的日期格式，您需要制作一个可以接受多种格式字符串的自定义 JsonConverter 并尝试直到成功为止.这是一个简单的例子:

If you want to handle multiple possible date formats, you will need to make a custom JsonConverter which can accept multiple format strings and try them all until one succeeds. Here is a simple example:

class MultiFormatDateConverter : JsonConverter
{
    public List<string> DateTimeFormats { get; set; }
    
    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(DateTime) || objectType == typeof(DateTime?);
    }
    
    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        string dateString = (string)reader.Value;
        if (dateString == null) 
        {
            if (objectType == typeof(DateTime?))
                return null;
                
            throw new JsonException("Unable to parse null as a date.");
        }
        DateTime date;
        foreach (string format in DateTimeFormats)
        {
            // adjust this as necessary to fit your needs
            if (DateTime.TryParseExact(dateString, format, CultureInfo.InvariantCulture, DateTimeStyles.None, out date))
                return date;
        }
        throw new JsonException("Unable to parse "" + dateString + "" as a date.");
    }
    
    public override bool CanWrite
    {
        get { return false; }
    }
    
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}

然后你可以像这样将它添加到你的设置中:

Then you can add it to your settings like this:

var settings = new JsonSerializerSettings();
settings.DateParseHandling = DateParseHandling.None;
settings.Converters.Add(new MultiFormatDateConverter 
{ 
    DateTimeFormats = new List<string> { "yyyyMMddTHHmmssZ", "yyyy-MM-ddTHH:mm" } 
});

小提琴:https://dotnetfiddle.net/vOpMEY

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