c# - 调用 DeserializeObject<> 时抛出 Newtonsoft.Json.JsonReaderException

Question

原谅我的无知，因为我是新手。我正在尝试从 Twitch 获取流信息，无论流是否直播。我通过使用HttpClient和 GET 请求来做到这一点。TwitchData将JSON 反序列化为对象的类如下。

public partial class TwitchData
{
    [JsonProperty("data")]
    public Datum[] Data { get; set; }

    [JsonProperty("pagination")]
    public Pagination Pagination { get; set; }
}

public partial class Datum
{
    [JsonProperty("id")]
    public string Id { get; set; }

    [JsonProperty("user_id")]
    [JsonConverter(typeof(ParseStringConverter))]
    public long UserId { get; set; }

    [JsonProperty("game_id")]
    [JsonConverter(typeof(ParseStringConverter))]
    public long GameId { get; set; }

    [JsonProperty("community_ids")]
    public object[] CommunityIds { get; set; }

    [JsonProperty("type")]
    public string Type { get; set; }

    [JsonProperty("title")]
    public string Title { get; set; }

    [JsonProperty("viewer_count")]
    public long ViewerCount { get; set; }

    [JsonProperty("started_at")]
    public DateTimeOffset StartedAt { get; set; }

    [JsonProperty("language")]
    public string Language { get; set; }

    [JsonProperty("thumbnail_url")]
    public string ThumbnailUrl { get; set; }
}

public partial class Pagination
{
    [JsonProperty("cursor")]
    public string Cursor { get; set; }
}

public partial class TwitchData
{
    public static TwitchData FromJson(string json) => JsonConvert.DeserializeObject<TwitchData>(json, QuickType.Converter.Settings);
}

public static class Serialize
{
    public static string ToJson(this TwitchData self) => JsonConvert.SerializeObject(self, QuickType.Converter.Settings);
}

internal static class Converter
{
    public static readonly JsonSerializerSettings Settings = new JsonSerializerSettings
    {
        MetadataPropertyHandling = MetadataPropertyHandling.Ignore,
        DateParseHandling = DateParseHandling.None,
        Converters = {
            new IsoDateTimeConverter { DateTimeStyles = DateTimeStyles.AssumeUniversal }
        },
    };
}

internal class ParseStringConverter : JsonConverter
{
    public override bool CanConvert(Type t) => t == typeof(long) || t == typeof(long?);

    public override object ReadJson(JsonReader reader, Type t, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null) return null;
        var value = serializer.Deserialize<string>(reader);
        long l;
        if (Int64.TryParse(value, out l))
        {
            return l;
        }
        throw new Exception("Cannot unmarshal type long");
    }

    public override void WriteJson(JsonWriter writer, object untypedValue, JsonSerializer serializer)
    {
        if (untypedValue == null)
        {
            serializer.Serialize(writer, null);
            return;
        }
        var value = (long)untypedValue;
        serializer.Serialize(writer, value.ToString());
        return;
    }

    public static readonly ParseStringConverter Singleton = new ParseStringConverter();
}

我使用以下内容执行 HttpClient GET 请求

HttpClient client = new HttpClient();
string uri = "https://api.twitch.tv/helix/streams?user_id=59980349";
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Client-ID", token);
var result = client.GetStringAsync(uri);
jsonString = result.ToString();
twitchData = PwdResetRequest.FromJson(jsonString);

当它运行时，Newtonsoft.Json.JsonReaderException, Unexpected character encountered while parsing value: S. Path '', line 0, position 0抛出。进一步调试，我发现程序在第 71 行中断，即

public static TwitchData FromJson(string json) => JsonConvert.DeserializeObject<TwitchData>(json, QuickType.Converter.Settings);

因为我从json2csharp.com获得了这个类，所以我不知道如何修复该行或抛出异常的原因。

编辑： 评论中要求使用 JSON。如果流是实时的，这是 JSON

{
  "data": [
    {
      "id": "30356128676",
      "user_id": "59788312",
      "game_id": "498652",
      "community_ids": [],
      "type": "live",
      "title": "A stream",
      "viewer_count": 1325,
      "started_at": "2018-09-07T16:30:09Z",
      "language": "en",
      "thumbnail_url": "url"
    }
  ],
  "pagination": {
    "cursor": "eydBIjpwdWGsLaJhIjp7IkGH4hNl6CH6MXr9"
  }
}

当它离线时

{
  "data": [],
  "pagination": {}
}

标签： c#jsonxamarin