ASP.Net Core 从外部 API 导入 JSON

Question

我是 .NET Core 主页的新手，有人可以指导我完成此操作。

我需要向这个 url 发出请求并将数据保存到数据库中： url: https://covid19.mathdro.id/api

JSON 输出如下所示：

{"confirmed":{"value":303001,"detail":"https://covid19.mathdro.id/api/confirmed"},"recovered":{"value":91669,"detail":"https://covid19.mathdro.id/api/recovered"},"deaths":{"value":12762,"detail":"https://covid19.mathdro.id/api/deaths"},"dailySummary":"https://covid19.mathdro.id/api/daily","dailyTimeSeries":{"pattern":"https://covid19.mathdro.id/api/daily/[dateString]","example":"https://covid19.mathdro.id/api/daily/2-14-2020"},"image":"https://covid19.mathdro.id/api/og","source":"https://github.com/mathdroid/covid19","countries":"https://covid19.mathdro.id/api/countries","countryDetail":{"pattern":"https://covid19.mathdro.id/api/countries/[country]","example":"https://covid19.mathdro.id/api/countries/USA"},"lastUpdate":"2020-03-21T20:13:21.000Z"}

型号：总计

public class Total
{
    [Key]
    public int Id { get; set; }
    [Column(TypeName = "int")]
    [Required]
    public string Confirmed { get; set; }
    [Column(TypeName = "int")]
    [Required]
    public string Recovered { get; set; }
    [Column(TypeName = "int")]
    [Required]
    public string Deaths { get; set; }
    [Column(TypeName = "datetime2")]
    [Required]
    public string LastUpdated { get; set; }
}

我的进口型号：

client.BaseAddress = new Uri("https://covid19.mathdro.id/api");
var response = await client.GetAsync($"");
response.EnsureSuccessStatusCode();
var stringResult = await response.Content.ReadAsStringAsync();

我被困在这里，无法继续。 如何获取数据，我只需要：确认、恢复、死亡和上次更新

请。 任何人在这里帮助...

Answer 1

您需要将JSON转换为Class Object 。 您可以使用NewtonSoft.Json获取这样的数据

using (var client = new HttpClient())
{
  string url = string.Format("https://covid19.mathdro.id/api");
  var response = client.GetAsync(url).Result;

  string responseAsString = await response.Content.ReadAsStringAsync();
  result = JsonConvert.DeserializeObject<CovidResult>(responseAsString);
}

public class CovidResult
{
   [JsonProperty("confirmed")]
   public ValueModel Confirmed { get; set; }
   [JsonProperty("recovered")]
   public ValueModel Recovered { get; set; }
   [JsonProperty("deaths")]
   public ValueModel Deaths { get; set; }
}

public class ValueModel
{
   [JsonProperty("value")]
   public int Value { get; set; }
}

你可以 fork 或下载这个 repo： https : //github.com/fatihyildizhan/CoronaParser

Answer 2

你的模态应该是

public class Total
{
    public Confirmed confirmed { get; set; }
    public Recovered recovered { get; set; }
    public Deaths deaths { get; set; }
    public string dailySummary { get; set; }
    public DailyTimeSeries dailyTimeSeries { get; set; }
    public string image { get; set; }
    public string source { get; set; }
    public string countries { get; set; }
    public CountryDetail countryDetail { get; set; }
    public DateTime lastUpdate { get; set; }
}

public class Confirmed
{
    public int value { get; set; }
    public string detail { get; set; }
}

public class Recovered
{
    public int value { get; set; }
    public string detail { get; set; }
}

public class Deaths
{
    public int value { get; set; }
    public string detail { get; set; }
}

public class DailyTimeSeries
{
    public string pattern { get; set; }
    public string example { get; set; }
}

public class CountryDetail
{
    public string pattern { get; set; }
    public string example { get; set; }
}

如果stringResult有一个实际值，你所要做的就是：

JsonConvert.DeserializeObject<Total>(stringResult);

此外，当对模态有疑问时，您可以随时使用http://json2csharp.com/

Answer 3

我建议你使用 JSon.NET 又名 Newtonsoft。 您可以从 nuget 包管理器添加它。 这是将传入的 json 数据映射到自定义类 Total 的代码。 只需添加您的类构造函数，它将 json 数据作为字符串类型的参数，并且我添加了一种方法来缩短代码

public class Total {

    public Total(string json) {
        JObject jObject = JObject.Parse(json);
        Confirmed = GetStringFromJToken(jObject, "confirmed");
        Recovered = GetStringFromJToken(jObject, "recovered");
        Deaths = GetStringFromJToken(jObject, "deaths");

        LastUpdated = (string)jObject["lastUpdate"];
    }

    private string GetStringFromJToken(JObject jObject, string key) {
        JToken keyToken = jObject[key];
        return (string)keyToken["value"];
    }

    [Key]
    public int Id { get; set; }
    [Column(TypeName = "int")]
    [Required]
    public string Confirmed { get; set; }
    [Column(TypeName = "int")]
    [Required]
    public string Recovered { get; set; }
    [Column(TypeName = "int")]
    [Required]
    public string Deaths { get; set; }
    [Column(TypeName = "datetime2")]
    [Required]
    public string LastUpdated { get; set; }
}