API返回JSON正常但JsonSerializer反序列化后值全为null求助

架构老林

2026-8-2

API反序列化后结果全为null问题排查

我调用API获取到了有效JSON数据，但使用JsonSerializer.Deserialize<Root>进行反序列化时，结果对象的所有值均为null，请求排查原因。

一、API返回的JSON数据

{
   "get":"leagues",
   "parameters":[
      
   ],
   "errors":[
      
   ],
   "results":960,
   "paging":{
      "current":1,
      "total":1
   },
   "response":[
      {
         "league":{
            "id":4,
            "name":"Euro Championship",
            "type":"Cup",
            "logo":"https://media-3.api-sports.io/football/leagues/4.png"
         },
         "country":{
            "name":"World",
            "code":null,
            "flag":null
         },
         "seasons":[
            {
               "year":2008,
               "start":"2008-06-07",
               "end":"2008-06-29",
               "current":false,
               "coverage":{
                  "fixtures":{
                     "events":true,
                     "lineups":true,
                     "statistics_fixtures":false,
                     "statistics_players":false
                  },
                  "standings":false,
                  "players":false,
                  "top_scorers":false,
                  "top_assists":false,
                  "top_cards":false,
                  "injuries":false,
                  "predictions":true,
                  "odds":false
               }
            },
            {
               "year":2012,
               "start":"2012-06-08",
               "end":"2012-07-01",
               "current":false,
               "coverage":{
                  "fixtures":{
                     "events":true,
                     "lineups":true,
                     "statistics_fixtures":false,
                     "statistics_players":false
                  },
                  "standings":false,
                  "players":false,
                  "top_scorers":false,
                  "top_assists":false,
                  "top_cards":false,
                  "injuries":false,
                  "predictions":true,
                  "odds":false
               }
            },
            {
               "year":2016,
               "start":"2016-06-10",
               "end":"2016-07-10",
               "current":false,
               "coverage":{
                  "fixtures":{
                     "events":true,
                     "lineups":true,
                     "statistics_fixtures":true,
                     "statistics_players":true
                  },
                  "standings":true,
                  "players":false,
                  "top_scorers":false,
                  "top_assists":false,
                  "top_cards":false,
                  "injuries":false,
                  "predictions":true,
                  "odds":false
               }
            },
            {
               "year":2020,
               "start":"2019-03-21",
               "end":"2021-07-11",
               "current":true,
               "coverage":{
                  "fixtures":{
                     "events":true,
                     "lineups":true,
                     "statistics_fixtures":true,
                     "statistics_players":true
                  },
                  "standings":true,
                  "players":true,
                  "top_scorers":true,
                  "top_assists":true,
                  "top_cards":true,
                  "injuries":false,
                  "predictions":true,
                  "odds":false
               }
            }
         ]
      }
   ]
}

注：原JSON末尾存在语法错误（response数组最后一个元素后多余的逗号），已修正

二、请求代码

public class LeagueService : ILeagueService
{
    public async Task GetLeaguesFromApiAsync()
    {
        var client = new HttpClient();
        var request = new HttpRequestMessage
        {
            Method = HttpMethod.Get,
            RequestUri = new Uri("-"),
            Headers =
            {
                { "X-RapidAPI-Key", "-" },
                { "X-RapidAPI-Host", "-" },
            }
        };

        using var response = await client.SendAsync(request);

        response.EnsureSuccessStatusCode();
        var body = await response.Content.ReadAsStringAsync();

        var result = JsonSerializer.Deserialize<Root>(body);
    }
}

三、Root类定义

public class Root
{
    public string Get { get; set; }
    public List<object> Parameters { get; set; }
    public List<object> Errors { get; set; }
    public int Results { get; set; }
    public Paging Paging { get; set; }
    public List<Response> Response { get; set; }
}

排查与解决要点：

修复JSON语法错误
原JSON中response数组的最后一个对象后多了一个逗号（},}），这属于无效JSON格式，System.Text.Json解析时会直接返回null。必须先修正这个错误，确保JSON格式合法。

处理属性名称大小写不匹配
System.Text.Json默认区分大小写，JSON中的键是小写（如"get"、"results"），但你的Root类属性是大写开头（Get、Results），导致映射失败。有两种解决方式：

给类属性添加[JsonPropertyName]特性，指定对应JSON键名：

public class Root
{
    [JsonPropertyName("get")]
    public string Get { get; set; }
    [JsonPropertyName("parameters")]
    public List<object> Parameters { get; set; }
    [JsonPropertyName("errors")]
    public List<object> Errors { get; set; }
    [JsonPropertyName("results")]
    public int Results { get; set; }
    [JsonPropertyName("paging")]
    public Paging Paging { get; set; }
    [JsonPropertyName("response")]
    public List<Response> Response { get; set; }
}

反序列化时配置JsonSerializerOptions，开启不区分大小写：

var options = new JsonSerializerOptions { PropertyNameCaseInsensitive = true };
var result = JsonSerializer.Deserialize<Root>(body, options);

补全嵌套类定义
你的Root类引用了Paging和Response类，但未提供这些类的定义。如果这些类不存在或属性映射错误，也会导致反序列化失败。需要补全所有嵌套类，确保属性与JSON键匹配：

public class Paging
{
    [JsonPropertyName("current")]
    public int Current { get; set; }
    [JsonPropertyName("total")]
    public int Total { get; set; }
}

public class Response
{
    [JsonPropertyName("league")]
    public League League { get; set; }
    [JsonPropertyName("country")]
    public Country Country { get; set; }
    [JsonPropertyName("seasons")]
    public List<Season> Seasons { get; set; }
}

public class League
{
    [JsonPropertyName("id")]
    public int Id { get; set; }
    [JsonPropertyName("name")]
    public string Name { get; set; }
    [JsonPropertyName("type")]
    public string Type { get; set; }
    [JsonPropertyName("logo")]
    public string Logo { get; set; }
}

public class Country
{
    [JsonPropertyName("name")]
    public string Name { get; set; }
    [JsonPropertyName("code")]
    public string Code { get; set; }
    [JsonPropertyName("flag")]
    public string Flag { get; set; }
}

public class Season
{
    [JsonPropertyName("year")]
    public int Year { get; set; }
    [JsonPropertyName("start")]
    public string Start { get; set; }
    [JsonPropertyName("end")]
    public string End { get; set; }
    [JsonPropertyName("current")]
    public bool Current { get; set; }
    [JsonPropertyName("coverage")]
    public Coverage Coverage { get; set; }
}

public class Coverage
{
    [JsonPropertyName("fixtures")]
    public Fixtures Fixtures { get; set; }
    [JsonPropertyName("standings")]
    public bool Standings { get; set; }
    [JsonPropertyName("players")]
    public bool Players { get; set; }
    [JsonPropertyName("top_scorers")]
    public bool TopScorers { get; set; }
    [JsonPropertyName("top_assists")]
    public bool TopAssists { get; set; }
    [JsonPropertyName("top_cards")]
    public bool TopCards { get; set; }
    [JsonPropertyName("injuries")]
    public bool Injuries { get; set; }
    [JsonPropertyName("predictions")]
    public bool Predictions { get; set; }
    [JsonPropertyName("odds")]
    public bool Odds { get; set; }
}

public class Fixtures
{
    [JsonPropertyName("events")]
    public bool Events { get; set; }
    [JsonPropertyName("lineups")]
    public bool Lineups { get; set; }
    [JsonPropertyName("statistics_fixtures")]
    public bool StatisticsFixtures { get; set; }
    [JsonPropertyName("statistics_players")]
    public bool StatisticsPlayers { get; set; }
}

捕获反序列化错误
可以通过捕获JsonException查看具体错误信息，帮助定位问题：

try
{
    var options = new JsonSerializerOptions { PropertyNameCaseInsensitive = true };
    var result = JsonSerializer.Deserialize<Root>(body, options);
}
catch (JsonException ex)
{
    Console.WriteLine($"反序列化错误：{ex.Message}");
}

内容的提问来源于stack exchange，提问作者alessoi1

API返回JSON正常但JsonSerializer反序列化后值全为null求助

一、API返回的JSON数据 #

二、请求代码 #

三、Root类定义 #

排查与解决要点： #

一、API返回的JSON数据

二、请求代码

三、Root类定义

排查与解决要点：