ASP.NET调用YesNo API反序列化JSON返回Null问题求助

我是ASP.NET新手，尝试向YesNo API发送GET请求，但在将JSON响应反序列化并赋值给变量时得到Null值，恳请协助解决！

控制器代码 #

[RoutePrefix("api/YesNo")]
public class YesNoController : ApiController
{
    [Route("GetYesNo")]
    public HttpResponseMessage GetYesNo()
    {
        Uri loginUrl = new Uri("https://yesno.wtf/api");
        HttpClient client = new HttpClient();
        client.BaseAddress = loginUrl;

        YesNoModel YesNoData = new YesNoModel();
        var httpResponse = Request.CreateResponse(HttpStatusCode.OK);

        HttpResponseMessage response = client.GetAsync(client.BaseAddress).Result;
        if (response.IsSuccessStatusCode)
        {
            string data = response.Content.ReadAsStringAsync().Result;
            YesNoData = JsonConvert.DeserializeObject<YesNoModel>(data);
        }

        httpResponse.Content = new StringContent(JsonConvert.SerializeObject(YesNoData), Encoding.UTF8, "application/json");
        return httpResponse;
    }
}

class YesNoModel
{ 
    string answer { get; set; }
    bool forced { get; set; }
    string image { get; set; }
}

Postman响应示例 #

{
    "answer": "no",
    "forced": false,
    "image": "https://yesno.wtf/assets/no/20-56c4b19517aa69c8f7081939198341a4.gif"
}

调试情况 #

• data变量已正确获取到API返回的完整JSON内容
• YesNoData变量的所有属性值均为Null

问题核心：YesNoModel的属性没有添加公共访问修饰符（public），Json.NET默认仅能序列化/反序列化公共属性，因此无法匹配JSON中的字段，导致属性值全部为Null。

1. 修正模型类 #

给YesNoModel的所有属性添加public修饰符：

public class YesNoModel
{ 
    public string answer { get; set; }
    public bool forced { get; set; }
    public string image { get; set; }
}

2. 可选优化建议 #

（1）使用异步/await替代.Result

避免阻塞线程，提升性能：

[Route("GetYesNo")]
public async Task<HttpResponseMessage> GetYesNo()
{
    Uri apiUrl = new Uri("https://yesno.wtf/api");
    using (HttpClient client = new HttpClient())
    {
        YesNoModel yesNoData = new YesNoModel();
        var httpResponse = Request.CreateResponse(HttpStatusCode.OK);

        HttpResponseMessage response = await client.GetAsync(apiUrl);
        if (response.IsSuccessStatusCode)
        {
            string data = await response.Content.ReadAsStringAsync();
            yesNoData = JsonConvert.DeserializeObject<YesNoModel>(data);
        }

        httpResponse.Content = new StringContent(JsonConvert.SerializeObject(yesNoData), Encoding.UTF8, "application/json");
        return httpResponse;
    }
}

（2）添加JsonProperty特性规范字段映射

如果后续使用C#标准的PascalCase命名（如Answer而非answer），可以通过JsonProperty特性明确对应JSON字段名：

public class YesNoModel
{ 
    [JsonProperty("answer")]
    public string Answer { get; set; }
    [JsonProperty("forced")]
    public bool Forced { get; set; }
    [JsonProperty("image")]
    public string Image { get; set; }
}

内容的提问来源于stack exchange，提问作者trickster625