将 JSON 数据从 API 转换为 C# 对象

Question

我正在尝试将 JSON 数据从 API 转换为 C# 对象，但出现以下错误：

无法将 JSON 值转换为 CountriesDemo.Models.CountryModel。路径：$ |行号：0 | BytePositionInLine：1

我的功能：

public static async Task getCountryData()
{
    var apiURL = "https://restcountries.com/v3.1/alpha/tto";

    HttpClient client = new HttpClient();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    var jsonResults = await client.GetStringAsync(apiURL);
    CountryModel? cshrpObj = System.Text.Json.JsonSerializer.Deserialize< CountryModel >(jsonResults);
    Console.WriteLine(cshrpObj?.name);
}

C#类：

public class CountryModel
{
    public string? name { get; set; }
    public string tld { get; set; } = null!;
    public string cca2 { get; set; } = null!;
    public string ccn3 { get; set; } = null!;
    public string cca3 { get; set; } = null!;
    public string cioc { get; set; } = null!;
    public string currency { get; set; } = null!;
    public string idd { get; set; } = null!;
    public string capital { get; set; } = null!;
    public string altSpellings { get; set; } = null!;
    public string region { get; set; } = null!;
    public string subregion { get; set; } = null!;
    public string languages { get; set; } = null!;
    public string translations { get; set; } = null!;
    public string latlng { get; set; } = null!;
    public string demonym { get; set; } = null!;
    public string landlocked { get; set; } = null!;
    public string borders { get; set; } = null!;
    public string area { get; set; } = null!;
}

API 数据片段

[
  {
    "name": {
        "common": "United States",
        "official": "United States of America",
        "nativeName": {
            "eng": {
                "official": "United States of America",
                "common": "United States"
            }
        }
    },
    "tld": [
        ".us"
    ],
    "cca2": "US",
    "ccn3": "840",
    "cca3": "USA",
    "cioc": "USA",
    "independent": true,
    "status": "officially-assigned",
    "unMember": true,
]

Answer 1

不幸的是你的 json 模型不正确。对于你发布的 json，你需要这个模型

    List<Country> myDeserializedClass = JsonSerializer.Deserialize<List<Country>>(jsonResults);

public class Country
{
    public Name name { get; set; }
    public List<string> tld { get; set; }
    public string cca2 { get; set; }
    public string ccn3 { get; set; }
    public string cca3 { get; set; }
    public string cioc { get; set; }
    public bool independent { get; set; }
    public string status { get; set; }
    public bool unMember { get; set; }
}
public class Eng
{
    public string official { get; set; }
    public string common { get; set; }
}

public class Name
{
    public string common { get; set; }
    public string official { get; set; }
    public NativeName nativeName { get; set; }
}

public class NativeName
{
    public Eng eng { get; set; }
}

Answer 2

那是因为您所指的 endpoint 返回一个对象数组，而不是直接返回一个对象。

尝试这个：

public static async Task getCountryData()
{
    var apiURL = "https://restcountries.com/v3.1/alpha/tto";

    HttpClient client = new HttpClient();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    var jsonResults = await client.GetStringAsync(apiURL);
    CountryModel[] cshrpObj = System.Text.Json.JsonSerializer.Deserialize<CountryModel[]>(jsonResults);

    Console.WriteLine(cshrpObj.First().name);
}