c# - 将 JSON 字符串反序列化为 C# 类

Question

好的，我会尽量简短具体。我从一个公共(public) API 获取一个 JSON 字符串，如下所示:(它的简短版本，只取了 2 个样本)

[{
    "$type": "Tfl.Api.Presentation.Entities.Line, Tfl.Api.Presentation.Entities",
    "id": "bakerloo",
    "name": "Bakerloo",
    "modeName": "tube",
    "disruptions": [],
    "created": "2017-03-16T15:56:01.01Z",
    "modified": "2017-03-16T15:56:01.01Z",
    "lineStatuses": [
      {
        "$type": "Tfl.Api.Presentation.Entities.LineStatus, Tfl.Api.Presentation.Entities",
        "id": 0,
        "statusSeverity": 10,
        "statusSeverityDescription": "Good Service",
        "created": "0001-01-01T00:00:00",
        "validityPeriods": []
      }
    ],
    "routeSections": [],
    "serviceTypes": [
      {
        "$type": "Tfl.Api.Presentation.Entities.LineServiceTypeInfo, Tfl.Api.Presentation.Entities",
        "name": "Regular",
        "uri": "/Line/Route?ids=Bakerloo&serviceTypes=Regular"
      }
    ],
    "crowding": {
      "$type": "Tfl.Api.Presentation.Entities.Crowding, Tfl.Api.Presentation.Entities"
    }
  },
  {
    "$type": "Tfl.Api.Presentation.Entities.Line, Tfl.Api.Presentation.Entities",
    "id": "central",
    "name": "Central",
    "modeName": "tube",
    "disruptions": [],
    "created": "2017-03-16T15:56:01.01Z",
    "modified": "2017-03-16T15:56:01.01Z",
    "lineStatuses": [
      {
        "$type": "Tfl.Api.Presentation.Entities.LineStatus, Tfl.Api.Presentation.Entities",
        "id": 0,
        "statusSeverity": 10,
        "statusSeverityDescription": "Good Service",
        "created": "0001-01-01T00:00:00",
        "validityPeriods": []
      }
    ],
    "routeSections": [],
    "serviceTypes": [
      {
        "$type": "Tfl.Api.Presentation.Entities.LineServiceTypeInfo, Tfl.Api.Presentation.Entities",
        "name": "Regular",
        "uri": "/Line/Route?ids=Central&serviceTypes=Regular"
      },
      {
        "$type": "Tfl.Api.Presentation.Entities.LineServiceTypeInfo, Tfl.Api.Presentation.Entities",
        "name": "Night",
        "uri": "/Line/Route?ids=Central&serviceTypes=Night"
      }
    ],
    "crowding": {
      "$type": "Tfl.Api.Presentation.Entities.Crowding, Tfl.Api.Presentation.Entities"
    }
  }]

到目前为止一切顺利，下面我将粘贴我正在使用的相关代码并尝试将此 JSON 字符串反序列化到我从 json2csharp 获得的 C# 类中免费在线服务。我试图实现这一目标的相关代码是:

public async static Task<tubeStatusRootObject> GetTubeStatus(string url)
{
    var http = new HttpClient();
    var response = await http.GetAsync(url);
    var result = await response.Content.ReadAsStringAsync(); //This is working
    var deserializer = new DataContractJsonSerializer(typeof(tubeStatusRootObject));
    var ms = new MemoryStream(Encoding.UTF8.GetBytes(result));
    var data = (tubeStatusRootObject)deserializer.ReadObject(ms);
    return data; //all "data" properties are null
}

正如你可以阅读上面的评论，我在返回之前得到的所有内部数据都是空的。

由 json2csharp 生成的类如下所示:

[DataContract]
public class Disruption
{
    [DataMember]
    public string type { get; set; }

    [DataMember]
    public string category { get; set; }

    [DataMember]
    public string categoryDescription { get; set; }

    [DataMember]
    public string description { get; set; }

    [DataMember]
    public string additionalInfo { get; set; }

    [DataMember]
    public string created { get; set; }

    [DataMember]
    public List<object> affectedRoutes { get; set; }

    [DataMember]
    public List<object> affectedStops { get; set; }

    [DataMember]
    public string closureText { get; set; }

    [DataMember]
    public bool? isWholeLine { get; set; }
}

[DataContract]
public class LineStatus
{
    [DataMember]
    public string type { get; set; }

    [DataMember]
    public int id { get; set; }

    [DataMember]
    public int statusSeverity { get; set; }

    [DataMember]
    public string statusSeverityDescription { get; set; }

    [DataMember]
    public string created { get; set; }

    [DataMember]
    public List<object> validityPeriods { get; set; }

    [DataMember]
    public string lineId { get; set; }

    [DataMember]
    public string reason { get; set; }

    [DataMember]
    public Disruption disruption { get; set; }
}

[DataContract]
public class ServiceType
{
    [DataMember]
    public string type { get; set; }

    [DataMember]
    public string name { get; set; }

    [DataMember]
    public string uri { get; set; }
}

[DataContract]
public class Crowding
{
    [DataMember]
    public string type { get; set; }
}

[DataContract]
public class tubeStatusRootObject
{
    [DataMember]
    public string type { get; set; }

    [DataMember]
    public string id { get; set; }

    [DataMember]
    public string name { get; set; }

    [DataMember]
    public string modeName { get; set; }

    [DataMember]
    public List<object> disruptions { get; set; }

    [DataMember]
    public string created { get; set; }

    [DataMember]
    public string modified { get; set; }

    [DataMember]
    public List<LineStatus> lineStatuses { get; set; }

    [DataMember]
    public List<object> routeSections { get; set; }

    [DataMember]
    public List<ServiceType> serviceTypes { get; set; }

    [DataMember]
    public Crowding crowding { get; set; }
}

显然，我只是在其中添加了 [DataContract] 和 [DataMember]。任何知道我做错了什么并且可以帮助我的人

我遵循了 Channel9 中的示例

请不要标记重复，因为我发现了很多类似的问题，有些问题使用 newtonsoft json 但我无法将那里的解决方案实现到我的示例中

Answer 1

提供的示例数据描述了一个数组 (tubeStatusRootObject[]) 但是当您尝试反序列化时，您将其转换为单个实例，这是一个无效的转换。这就是为什么 data 为 null 的原因。

如果有可用的工具来简单地解决问题，也无需重新发明轮子。

static http = new HttpClient(); //reuse httpclient instead of creating a new one each time.
public async static Task<tubeStatusRootObject[]> GetTubeStatus(string url) {
    var response = await http.GetAsync(url); 
    var json = await response.Content.ReadAsStringAsync(); //This is working
    var data = Newtonsoft.Json.JsonConvert.DeserializeObject<tubeStatusRootObject[]>(json);
    return data;
}