RestSharp升级后枚举反序列化失败，求IRestSerializer自定义实现

升级RestSharp从106.12.0到110.2.0后，出现枚举类型反序列化失败错误：

The JSON value could not be converted to SubExCore.Models.Enums.YearType. Path: $.body.YearType | LineNumber: 0 | BytePositionInLine:
The JSON value could not be converted to System.Nullable`1[SubExCore.Models.Enums.SectionType]. Path: $.body.sectionType | LineNumber: 0 | BytePositionInLine

问题根源 #

1. 新版RestSharp废弃了旧的RestSharp.Serializers.ISerializer接口，强制使用IRestSerializer
2. 默认序列化器切换为System.Text.Json，未沿用旧版本基于Newtonsoft.Json的自定义配置（字符串枚举转换、日期处理等）
3. 原API代码中重复创建RestRequest，导致自定义序列化器未被正确应用

解决方案 #

1. 自定义IRestSerializer实现（保留原Newtonsoft.Json配置） #

以下实现完全兼容旧版本的序列化逻辑，同时适配新版RestSharp的接口要求：

using RestSharp;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System.IO;
using System;

public class CustomNewtonsoftSerializer : IRestSerializer
{
    private readonly JsonSerializer _serializer;

    public CustomNewtonsoftSerializer()
    {
        var settings = new JsonSerializerSettings
        {
            Converters =
            {
                new StringEnumConverter(), // 字符串与枚举互转
                new DateTimeJsonConverter() // 保留原自定义日期转换器
            },
            DateTimeZoneHandling = DateTimeZoneHandling.Utc,
            ContractResolver = new CamelCasePropertyNamesContractResolver()
        };
        _serializer = JsonSerializer.Create(settings);
    }

    public string ContentType { get; set; } = "application/json";

    public string Serialize(object obj)
    {
        using var stringWriter = new StringWriter();
        using var jsonWriter = new JsonTextWriter(stringWriter);
        _serializer.Serialize(jsonWriter, obj);
        return stringWriter.ToString();
    }

    public T Deserialize<T>(IRestResponse response)
    {
        using var stringReader = new StringReader(response.Content);
        using var jsonReader = new JsonTextReader(stringReader);
        return _serializer.Deserialize<T>(jsonReader);
    }

    public string Serialize(Parameter parameter) => Serialize(parameter.Value);

    public bool SupportsContentType(string contentType)
    {
        return contentType.Contains("json", StringComparison.OrdinalIgnoreCase);
    }
}

2. 修正后的API调用代码 #

修复重复创建RestRequest的问题，确保自定义序列化器被正确绑定：

public YearBook GetYearBook()
{
    // 仅创建一次RestRequest，避免覆盖配置
    var request = new RestRequest(ApiPath, Method.Get)
    {
        Serializer = new CustomNewtonsoftSerializer() // 绑定自定义序列化器
    };

    var options = new RestClientOptions(BaseAddress)
    {
        CachePolicy = new System.Net.Http.Headers.CacheControlHeaderValue 
        { 
            NoCache = true, 
            NoStore = true 
        }
    };

    using var client = new RestClient(options);

    if (!string.IsNullOrWhiteSpace(Token))
    {
        client.AddDefaultHeader("Authorization", $"authToken {Token}");
    }
    client.AddDefaultHeader("Cache-Control", "no-cache");

    var response = client.Execute<YearBook>(request);
    return response.Data;
}

额外注意事项 #

• 确保项目中保留DateTimeJsonConverter类的实现（与旧版本一致）
• 若JSON字段为蛇形命名（如year_id），而模型属性为驼峰命名（如Year），需调整契约解析器为蛇形命名策略：

  ContractResolver = new DefaultContractResolver
  {
      NamingStrategy = new SnakeCaseNamingStrategy()
  }
  

  或在模型属性上添加[JsonProperty("year_id")]特性
• 新版RestSharp推荐使用异步方法ExecuteAsync替代同步Execute，可根据项目需求调整

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