c# - json 字符串 : take only top level with JSON. NET 的部分序列化

Question

请为我澄清一些困惑:我有一个 JSON 字符串，我试图将其粘贴到一个对象中，但我只想进入顶层，并将下面的所有内容视为 blob 或字符串。像这样。

这是我的模型:

public class InputJson
{
    [JsonProperty(PropertyName = "signals")]
    public string signals{ get; set; }
    [JsonProperty(PropertyName = "options")]
    public string options { get; set; }
    [JsonProperty(PropertyName = "fields")]
    public string fields{ get; set; }
    [JsonProperty(PropertyName = "lapse")]
    public string lapse{ get; set; }
}

我正在尝试将 JSON 字符串(见下文)反序列化为它:

InputJson a = JsonConvert.DeserializeObject<InputJson>(body);

我希望 a.signals 会返回一个字符串，包含“signals”下方和“options”之前的所有内容，但它失败了，因为它试图继续并序列化它下方的所有内容。我得到一个 JsonReaderException:

Error reading string. Unexpected token: StartArray. Path 'signals', line 1, position 12.

我尝试使用 JsonSerializerSettings(比如将 maxDepth 设置为 1)但没有任何帮助。有人吗？

我的 JSON 字符串:

{
    "signals":
    [
        {
            "name":"1",
            "att1":"44",
            "att2":"0",
            "att3":"18",
            "size":10,
            "points":[-79,-29,-9,-23,27,-110,-39,-22,-32,-2]
        },
        {
            "name":"2",
            "att1":"46",
            "att2":"0",
            "att3":"12",
            "size":10,
            "points":[36,37,37,35,38,41,41,45,39,41]
        }
    ],
    "options":"opt1 opt2",
    "fields":"myfields",
    "lapse":"somelapse"
}

Answer 1

正如您正确推测的那样，您收到此错误是因为您的字段是字符串并且反序列化程序已找到一个数组。它不能将数组分配给字符串。

您可以通过对要视为“blob”的字段使用自定义 JsonConverter 来解决此问题，我假设您的意思是您只需要原始 JSON 字符串。

这是转换器所需的代码:

class BlobJsonConverter: JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return (objectType == typeof(string));
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        JToken token = JToken.Load(reader);
        return token.ToString(Formatting.None);
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}

然后，在您的模型中，使用如下所示的 [JsonConverter] 属性装饰那些您希望视为“blob”的字符串属性:

public class InputJson
{
    [JsonProperty(PropertyName = "signals")]
    [JsonConverter(typeof(BlobJsonConverter))]
    public string signals { get; set; }

    [JsonProperty(PropertyName = "options")]
    public string options { get; set; }

    [JsonProperty(PropertyName = "fields")]
    public string fields { get; set; }

    [JsonProperty(PropertyName = "lapse")]
    public string lapse { get; set; }
}

现在，当您反序列化时，signals 将在“signals”下包含原始 JSON，而不是给出错误。

演示:

class Program
{
    static void Main(string[] args)
    {
        string json = @"
        {
            ""signals"":
            [
                {
                    ""name"":""1"",
                    ""att1"":""44"",
                    ""att2"":""0"",
                    ""att3"":""18"",
                    ""size"":10,
                    ""points"":[-79,-29,-9,-23,27,-110,-39,-22,-32,-2]
                },
                {
                    ""name"":""2"",
                    ""att1"":""46"",
                    ""att2"":""0"",
                    ""att3"":""12"",
                    ""size"":10,
                    ""points"":[36,37,37,35,38,41,41,45,39,41]
                }
            ],
            ""options"":""opt1 opt2"",
            ""fields"":""myfields"",
            ""lapse"":""somelapse""
        }";

        InputJson a = JsonConvert.DeserializeObject<InputJson>(json);
        Console.WriteLine("signals: " + a.signals);
        Console.WriteLine("options: " + a.options);
        Console.WriteLine("fields: " + a.fields);
        Console.WriteLine("lapse: " + a.lapse);
    }
}

输出:

signals: [{"name":"1","att1":"44","att2":"0","att3":"18","size":10,"points":[-79,-29,-9,-23,27,-110,-39,-22,-32,-2]},{"name":"2","att1":"46","att2":"0","att3":"12","size":10,"points":36,37,37,35,38,41,41,45,39,41]}]
options: opt1 opt2
fields: myfields
lapse: somelapse