反序列化没有属性名称的复杂 JSON 响应

Question

我想从我的 ASP.Net Core 应用程序中调用 API，但响应格式不是很好：

[
  {
    page: 1,
    pages: 1,
    per_page: 50,
    total: 2,
    sourceid: "2",
    sourcename: "World Development Indicators",
    lastupdated: "2021-10-28"
  },
  [
    {
      indicator: {
        id: "NY.GDP.PCAP.KD.ZG",
        value: "GDP per capita growth (annual %)"
      },
      country: {
        id: "CA",
        value: "Canada"
      },
      countryiso3code: "CAN",
      date: "2020",
      value: -6.33904652535297,
      unit: "",
      obs_status: "",
      decimal: 1
    },
    {
      indicator: {
        id: "NY.GDP.PCAP.KD.ZG",
        value: "GDP per capita growth (annual %)"
      },
      country: {
        id: "CA",
        value: "Canada"
      },
      countryiso3code: "CAN",
      date: "2019",
      value: 0.43021113414872,
      unit: "",
      obs_status: "",
      decimal: 1
    }
  ]
]

这里是 API 网址： https://api.worldbank.org/v2/country/can/indicator/NY.GDP.PCAP.KD.ZG?format=json&mrv=2

我已经为响应键入了这些类：

public class WorldBankApiResponseGlobal
  {
    public int Page { get; set; }
    public int Pages { get; set; }
    public int Per_Page { get; set; }
    public int Total { get; set; }
    public string Sourceid { get; set; }
    public string Sourcename { get; set; }
  }

  public class WorldBankApiIdValue
  {
    public string Id { get; set; }
    public string Value { get; set; }
  }

  public class WorldBankApiResponse
  {
    public WorldBankApiIdValue Indicator { get; set; }
    public WorldBankApiIdValue Country { get; set; }
    public int Value { get; set; }
    public string Date { get; set; }
    public string Countryiso3code { get; set; }
  }

但是，由于响应没有对象的属性值（即：[{},[]] 而不是 ["data": {}, "indicators": []]，我不知道如何正确反序列化 API 调用响应...

通常，我会这样做：

var response = await _client.GetFromJsonAsync<List<WorldBankApiResponseGlobal>>(worldBankApiUrl);

但是有谁知道我会如何处理这种响应类型？

Answer 1

试试这个。在 Visual Studio 中测试过

var parsedArray=JArray.Parse(json);

// this is just an array part
List<WorldBankApiResponse> worldBankApiResponses =  
JsonConvert.DeserializeObject<List<WorldBankApiResponse>>(parsedArray[1].ToString());

// this is just a header part
var wb = 
JsonConvert.DeserializeObject<WorldBankApiResponseGlobal>(parsedArray[0].ToString());

//this is the whole object
 var worldBankApiResponseGlobal= new WorldBankApiResponseGlobal{
     Page=wb.Page,
     Pages=wb.Pages,
     PerPage=wb.PerPage,
     Total=wb.Total,
     Sourceid=wb.Sourceid,
     Sourcename=wb.Sourcename,
     Lastupdated=wb.Lastupdated,
     WorldBankApiResponses=  worldBankApiResponses
 };

类

public partial class WorldBankApiResponseGlobal
    {
        [JsonProperty("page")]
        public long Page { get; set; }

        [JsonProperty("pages")]
        public long Pages { get; set; }

        [JsonProperty("per_page")]
        public long PerPage { get; set; }

        [JsonProperty("total")]
        public long Total { get; set; }

        [JsonProperty("sourceid")]
        public long Sourceid { get; set; }

        [JsonProperty("sourcename")]
        public string Sourcename { get; set; }

        [JsonProperty("lastupdated")]
        public DateTimeOffset Lastupdated { get; set; }

        [JsonProperty("WorldBankApiResponses")]
        public List<WorldBankApiResponse> WorldBankApiResponses { get; set; }
    }

    public partial class WorldBankApiResponse
    {
        [JsonProperty("indicator")]
        public WorldBankApiIdValue Indicator { get; set; }

        [JsonProperty("country")]
        public WorldBankApiIdValue Country { get; set; }

        [JsonProperty("countryiso3code")]
        public string Countryiso3Code { get; set; }

        [JsonProperty("date")]
        public long Date { get; set; }

        [JsonProperty("value")]
        public double Value { get; set; }

        [JsonProperty("unit")]
        public string Unit { get; set; }

        [JsonProperty("obs_status")]
        public string ObsStatus { get; set; }

        [JsonProperty("decimal")]
        public long Decimal { get; set; }
    }

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

        [JsonProperty("value")]
        public string Value { get; set; }
    }

Answer 2

我不知道您是否可以使用 GetFromJsonAsync 但使用 Newtonsoft.Json 来做到这一点。您可以制作一个特殊的转换来检查令牌是数组还是对象。并反序列化为合适的类型。

class WorldBankApiResponseUnionConverter : JsonConverter
{
    public override bool CanConvert(Type t) => t == typeof(WorldBankApiResponseUnion) || t == typeof(WorldBankApiResponseUnion?);

    public override object ReadJson(JsonReader reader, Type t, object existingValue, JsonSerializer serializer)
    {
        switch (reader.TokenType)
        {
            case JsonToken.StartObject:
                var objectValue = serializer.Deserialize<WorldBankApiResponseGlobal>(reader);
                return new WorldBankApiResponseUnion { WorldBankApiResponseGlobal = objectValue };
            case JsonToken.StartArray:
                var arrayValue = serializer.Deserialize<WorldBankApiResponse[]>(reader);
                return new WorldBankApiResponseUnion { WorldBankApiResponse = arrayValue };
        }
        throw new Exception("Cannot unmarshal type WorldBankApiResponseUnion");
    }

现场演示：https://dotnetfiddle.net/3Rqnya
使用自动化工具：https://app.quicktype.io/?l=csharp

Answer 3

编辑：上面发布https://app.quicktype.io/?l=csharp 以生成解决方案的评论看起来可以解决问题，尽管它会生成大量代码。如果有一个简单的方法来删除标题，下面会是一个更好的选择。

我不确定如何删除“标题”，但也许您可以排除“标题”以保留核心数据，然后您会留下一些可能是列表的东西

public class WorldBankApiResponse
{
  public WorldBankApiIdValue Indicator { get; set; }
  public WorldBankApiIdValue Country { get; set; }
  public int Value { get; set; }
  public string Date { get; set; }
  public string Countryiso3code { get; set; }
}

Answer 4

您可以使用JsonDocument from System.Text.Json 将顶级数组中的第一项和第二项反序列化为单独的对象，而无需使用 GetFromJsonAsync。

var json = @"
[
  { ""page_count"": 10 },
  [
    { ""id"": 1 },
    { ""id"": 2 }
  ]
]
";

class Header
{
    public int page_count { get; set; }
}
class Item
{
    public int id { get; set; }
}

using var document = JsonDocument.Parse(json);
var header = document.RootElement[0].Deserialize<Header>();
var body = document.RootElement[1].Deserialize<List<Item>>();

如果您使用的是 Newtonsoft.Json，则等效为 JArray（通常是 JToken）：

var jarray = JArray.Parse(json);
var header = jarray[0].ToObject<Header>();
var body = jarray[1].ToObject<List<Item>>();