将 API 映射到对象 C#

Question

我试图将 API 映射到一个对象，但出现错误：

Newtonsoft.Json.JsonSerializationException: 'Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.Generic.List'1[APIWebApp.Models.UserModel]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly. To fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type (e.g. not a primitive type like integer, not a collection type like an array or List) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object. Path '@count', line 2, position 11.'

这是我的代码：

函数到运行映射：

public List<UserModel> GetUserList()
        {
            try
            {
                using (WebClient webClient = new WebClient())
                {
                    webClient.Credentials = new NetworkCredential("un", "pw");
                    webClient.BaseAddress = StaticItems.EndPoint;
                    var json = webClient.DownloadString("userlist?view=expand");
                    var list = JsonConvert.DeserializeObject < List<UserModel>>(json);
                    return list.ToList();
                }
            }
            catch (WebException ex)
            {
                throw ex;
            }
        }

public static class StaticItems
{
    public static string EndPoint = "https://XXXXXX";
}

这是模型：

namespace APIWebApp.Models
{
    public class UserModel
    {
        public int count { get; set; }
        public int start { get; set; }
        public int totalcount { get; set; }
        public object[] Messages { get; set; }
        public string ResourceName { get; set; }
        public int ReturnCode { get; set; }
        public Content[] content { get; set; }
    }
    
    public class Content
    {
        public Users user { get; set; }
    }

    public class Users
    {
        public string name { get; set; }
        public string age { get; set; }
        public string date { get; set; }
    }
}

API json:

{
  "@count": 2,
  "@start": 1,
  "@totalcount": 2,
  "Messages": [],
  "ResourceName": "user",
  "ReturnCode": 0,
  "content": [
    {"user": {
      "name": "Eric",
      "age": "25",
      "date": "2021-10-23T11:18:10+00:00",
    }},
    {"user": {
      "name": "Paul",
      "age": "30",
      "date": "2021-10-23T11:18:10+00:00",
    }}]
}

如何修复导致错误的原因？

Answer 1

如果您只需要用户列表，只需 return 个用户

public List<User> GetUserList()
        {
            try
            {
                using (WebClient webClient = new WebClient())
                {
                    webClient.Credentials = new NetworkCredential("un", "pw");
                    webClient.BaseAddress = StaticItems.EndPoint;
                    var json = webClient.DownloadString("userlist?view=expand");
                    var list = JsonConvert.DeserializeObject<List<UserModel>>(json);
    
                    List<User> userList = new List<User>();
                    foreach (var item in list.content)
                    {
                        userList.Add(item.user);
                    }
                    return userList;
                }
            }
            catch (WebException ex)
            {
                throw ex;
            }
        }

Answer 2

欢迎光临！ return 被你的 API 编辑的 JSON 是 UserModel 而不是 List<UserModel>，所以首先你需要将 json 反序列化为 UserModel。然后，您可以 return GetUsersList() 中的任何内容，UserModel 或 List<Users>（如下所示）。

using (WebClient webClient = new WebClient())
    {
          webClient.Credentials = new NetworkCredential("un", "pw");
          webClient.BaseAddress = StaticItems.EndPoint;
          var json = webClient.DownloadString("userlist?view=expand");
          UserModel userModel = JsonConvert.DeserializeObject <UserModel>(json); // here
          return userModel.content.Select(c => c.user).ToList();
    }

Answer 3

请更改您的（UserModel）模型class

您的模特class

public class UserModel
{
    public int count { get; set; }
    public int start { get; set; }
    public int totalcount { get; set; }
    public object[] Messages { get; set; }
    public string ResourceName { get; set; }
    public int ReturnCode { get; set; }
    public Content[] content { get; set; }
}

已修改class

public class UserModel
{
    public int count { get; set; }
    public int start { get; set; }
    public int totalcount { get; set; }
    public List<object> Messages { get; set; }
    public string ResourceName { get; set; }
    public int ReturnCode { get; set; }
    public List<Content> content { get; set; }
}

这将正确反序列化对象。

将 API 映射到对象 C#

Mapping API to Object C#

c#

json

api

mapping