UWP应用调用RapidAPI获取公共假日后反序列化字段为空求助

问题场景 #

开发UWP应用的公共假日功能，调用RapidAPI的Public Holidays接口时，调试输出能看到完整的JSON响应内容，但将响应反序列化为RootObj类实例后，访问name、date、type等字段均返回空值。

相关代码 #

API调用代码 #

var client = new HttpClient();
var request = new HttpRequestMessage
{
    Method = HttpMethod.Get,
    RequestUri = new Uri("https://public-holiday.p.rapidapi.com/2023/SG"),
    Headers =
    {
        { "X-RapidAPI-Key", "API-Key" },
        { "X-RapidAPI-Host", "public-holiday.p.rapidapi.com" },
    },
};
using (var response = await client.SendAsync(request))
{
    response.EnsureSuccessStatusCode();
    var body = await response.Content.ReadAsStringAsync();
    var serializer = new DataContractJsonSerializer(typeof(RootObj));
    Debug.WriteLine(body);
    var ms = new MemoryStream(Encoding.UTF8.GetBytes(body));
    var data = (RootObj)serializer.ReadObject(ms);
    return data;
}

RootObj类定义 #

public class RootObj
{
    [DataMember]
    public string date { get; set; }
    [DataMember]
    public string localName { get; set; }
    [DataMember]
    public string name { get; set; }
    [DataMember]
    public string countryCode { get; set; }
    [DataMember]
    public bool @fixed { get; set; }
    [DataMember]
    public bool global { get; set; }
    [DataMember]
    public object counties { get; set; }
    [DataMember]
    public object launchYear { get; set; }
    [DataMember]
    public string type { get; set; }
}

MainPage调用代码 #

RootObj myHolidays = await GetHolidays();
holidayTextBlock.Text = myHolidays.name + " - " + myHolidays.date + " - " + myHolidays.type;

问题原因 #

1. 接口返回格式不匹配：RapidAPI的该接口返回的是JSON数组（包含多个假日对象），但当前代码尝试将其反序列化为单个RootObj实例，导致序列化失败，所有字段为空。
2. 缺少类级DataContract特性：RootObj类仅标记了[DataMember]成员特性，但未添加类级别的[DataContract]特性，DataContractJsonSerializer无法识别类的序列化规则，导致成员无法被正确赋值。

解决方案 #

1. 修正RootObj类，添加DataContract特性 #

[DataContract] // 必须添加类级别的DataContract特性
public class RootObj
{
    [DataMember]
    public string date { get; set; }
    [DataMember]
    public string localName { get; set; }
    [DataMember]
    public string name { get; set; }
    [DataMember]
    public string countryCode { get; set; }
    [DataMember]
    public bool @fixed { get; set; }
    [DataMember]
    public bool global { get; set; }
    [DataMember]
    public object counties { get; set; }
    [DataMember]
    public object launchYear { get; set; }
    [DataMember]
    public string type { get; set; }
}

2. 修改API调用方法，反序列化为数组类型 #

调整GetHolidays方法的返回类型为Task<RootObj[]>，并将序列化目标改为数组：

public async Task<RootObj[]> GetHolidays()
{
    var client = new HttpClient();
    var request = new HttpRequestMessage
    {
        Method = HttpMethod.Get,
        RequestUri = new Uri("https://public-holiday.p.rapidapi.com/2023/SG"),
        Headers =
        {
            { "X-RapidAPI-Key", "API-Key" },
            { "X-RapidAPI-Host", "public-holiday.p.rapidapi.com" },
        },
    };
    using (var response = await client.SendAsync(request))
    {
        response.EnsureSuccessStatusCode();
        var body = await response.Content.ReadAsStringAsync();
        Debug.WriteLine(body);
        // 反序列化为RootObj数组
        var serializer = new DataContractJsonSerializer(typeof(RootObj[]));
        var ms = new MemoryStream(Encoding.UTF8.GetBytes(body));
        var data = (RootObj[])serializer.ReadObject(ms);
        return data;
    }
}

3. 调整MainPage中的调用逻辑 #

现在返回的是数组，需遍历或取指定元素来显示：

RootObj[] myHolidays = await GetHolidays();
// 示例：取第一个假日数据显示
if (myHolidays.Length > 0)
{
    var firstHoliday = myHolidays[0];
    holidayTextBlock.Text = $"{firstHoliday.name} - {firstHoliday.date} - {firstHoliday.type}";
}

内容的提问来源于stack exchange，提问作者Kim