使用Refit反序列化Digicert API响应至实体类失败问题排查

我正在使用Refit + HttpClient Factory对接Digicert Automation API。当接口方法声明返回string类型（Task<string> GetAgentList([Body] GetAgentListReq req);）时，返回的字符串显示API返回了预期的JSON结果，其中data成员包含agentList数组。但将接口方法改为返回自定义的AgentList类（Task<AgentList> GetAgentList([Body] GetAgentListReq req);）后，反序列化未抛出异常，但data.agentList成员为null。直接使用System.Text.Json.JsonSerializer.Deserialize<AgentList>反序列化该字符串也得到data.agentList为null的对象，因此我怀疑是实体类定义存在问题。

接口与实体类代码 #

using Refit;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Digicert.Automation.API.Client
{
    [Headers("X-DC-DEVKEY: redacted")]
    public interface IDigicertAutomation
    {
        [Post("/agent/basicdetails")]
        Task<ApiResponse<IEnumerable<AgentSummary>>> GetAgentSummary(AgentSummaryReq req);

        [Post("/agent/list")]
        //Task<string> GetAgentList([Body] GetAgentListReq req);
        Task<AgentList> GetAgentList([Body] GetAgentListReq req);
    }

    public class AgentSummaryReq
    {
        public required string licensekey { get; set; }
        public int accountId { get; set; }
        public int divisionId { get; set; }
    }

    public class GetAgentListReq
    {
        public int accountId { get; set; }
        public class Criterion
        {
            public required string key;
            public required string operation;
            public required List<string> value;
        }
        public required Criterion[] searchCriteriaList { get; set; }
        public required int[] divisionIds { get; set; }
        public int startIndex;
        public int pageSize;
        public required Dictionary<string, string> sorting { get; set; }
    }

    public class Error
    {
        public required string message { get; set; }
        public required List<string> detailedMessage { get; set; }
        public required string errorCode { get; set; }
    }

    public class AgentSummary
    {
        public required Error error { get; set; }
        public class Data
        {
            public required string licenseKey { get; set; }
            public required string agentName { get; set; }
            public int updatePreference { get; set; }
            public required string stateString { get; set; }
            public required string agentVersion { get; set; }
            public bool updateAvailable { get; set; }
            public bool publishUpgradeOption { get; set; }
            public required string emailAddresses { get; set; }
        }
        public required Data data { get; set; }
    }
    public class AgentList
    {
        public required string error { get; set; }
        public class AgentListdata
        {
            public required List<AgentInfo> agentList;
        } 
        public required AgentListdata data {get;set;}
    }

    public class AgentInfo
    {
        public int agentId { get; set; }
        public required string accountId { get; set; }
        public required string divisionId { get; set; }
        public required string hostname { get; set; }
        public required string agentName { get; set; }
        public required string status { get; set; }
        public required string sensorName { get; set; }
        public required string type { get; set; }
        public required string agentLicense { get; set; }
        public int updatePreference { get; set; }
        public bool updateAvailable { get; set; }
    }
}

控制台调用代码 #

using Microsoft.Extensions.Hosting;
using Refit;
using Digicert.Automation.API;
using Microsoft.Extensions.DependencyInjection;
using Digicert.Automation.API.Client;
using static Digicert.Automation.API.Client.GetAgentListReq;
using System.Diagnostics;

namespace ConsoleApp1
{
    internal class Program
    {
        static async Task Main(string[] args)
        {
            using IHost host = Host.CreateDefaultBuilder(args)
                .ConfigureServices((_, services) =>
                {
                    services
                    .AddRefitClient<IDigicertAutomation>()
                    .ConfigureHttpClient(c => c.BaseAddress = new Uri("https://caas.digicert.com/automationws/v1/"));
                }).Build();

            var automationClient = host.Services.GetRequiredService<IDigicertAutomation>();

            var sorting = new Dictionary<string, string>
            {
                { "AGENTNAME", "ASC" },
            };
            var req = new GetAgentListReq() { accountId = 1349264, searchCriteriaList = Array.Empty<Criterion>(), divisionIds = Array.Empty<int>(), startIndex = 0, pageSize = 50, sorting = sorting };

            var results = await automationClient.GetAgentList(req);
            //var result = results.Content;
            //var x = results.RequestMessage?.Content;
            
            //if (result?.data != null && result?.data.agentList != null)
            //{
            //    foreach (var a in result.data.agentList)
            //    {
            //        Console.Out.WriteLine(a.agentName);
            //    }
            //}
        }
    }
}

解决方案 #

问题出在AgentListdata类里的agentList字段——你用的是字段而不是属性。System.Text.Json默认只序列化/反序列化带get; set;的属性，字段默认会被忽略，所以反序列化时agentList始终为null。

修改AgentListdata类，把agentList改成属性：

public class AgentList
{
    public required string error { get; set; }
    public class AgentListdata
    {
        // 把字段改成属性
        public required List<AgentInfo> agentList { get; set; }
    } 
    public required AgentListdata data { get; set; }
}

另外检查GetAgentListReq里的startIndex和pageSize，同样是字段，若API要求这些参数必须序列化，也需要改成属性：

public class GetAgentListReq
{
    public int accountId { get; set; }
    public class Criterion
    {
        public required string key { get; set; }
        public required string operation { get; set; }
        public required List<string> value { get; set; }
    }
    public required Criterion[] searchCriteriaList { get; set; }
    public required int[] divisionIds { get; set; }
    // 改成属性
    public int startIndex { get; set; }
    public int pageSize { get; set; }
    public required Dictionary<string, string> sorting { get; set; }
}

修改完成后，反序列化就能正确识别agentList数组了。

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