asp.net web api - 將對象發布到 web api

Question

我正在嘗試將用戶對象從 ac# 客戶端應用程序發布到應將新用戶存儲到數據庫中的 web api。 該模型基於同一類。 目前客戶端這個功能用於做帖子：

public static async Task CreateNewUser(string userName, string eMail, string password, string name, string firstName)
        {
            User newUser = new User(userName, eMail, password, name, firstName);
            using (var client = new HttpClient())
            {
                client.BaseAddress = new Uri(restAddress);
                try
                {
                    var response = await client.PostAsync(restAddress + "api/Users", newUser);
                    response.EnsureSuccessStatusCode();
                }
                catch (Exception e)
                {

                    ExecutionConsole.WriteError(e.ToString());
                }
            }
        }

而 Web API 中的控制器有這個功能：

// POST: api/Users
        [ResponseType(typeof(User))]
        public async Task<IHttpActionResult> PostUser(User user)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            db.Users.Add(user);

            try
            {
                await db.SaveChangesAsync();
            }
            catch (DbUpdateException)
            {
                if (UserExists(user.Username))
                {
                    return Conflict();
                }
                else
                {
                    throw;
                }
            }

            return CreatedAtRoute("DefaultApi", new { id = user.Username }, user);
        }

API 返回 400（錯誤請求）。 Web API 目前有這樣的配置：

 public void Configuration(IAppBuilder appBuilder)
        {
            HttpConfiguration config = new HttpConfiguration();
            config.MapHttpAttributeRoutes();
            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

            appBuilder.UseWebApi(config);
        }

編輯：

用戶模型：

public class User
            {
                public User(string userName, string email, string password) : this(userName, email, password, null, null)
                {

                }
                public User(string userName, string email, string password, string Name, string firstName)
                {
                    this.Username = userName;
                    this.Email = email;
                    this.Password = password;
                    this.Name = Name;
                    this.firstName = firstName;
                }

                [Key, Required]
                public string Username { get; set; }
                public string Name { get; set; }
                public string firstName { get; set; }
                [Required]
                public string Email { get; set; }
                [Required]
                public string Password { get; set; }
                public virtual ICollection<Playlist> CreatedPlaylists { get; set; }
                public virtual ICollection<Track> SavedTracks { get; set; }

            }

HTTPRequest（Rest API 是我的 Web API 項目的名稱）：

{Method: POST, RequestUri: 'http://localhost:2468/api/Users', Version: 1.1, Content: System.Net.Http.ObjectContent`1[[RestAPI.Model.User, RestAPI, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], Headers:
{
  Content-Type: application/json; charset=utf-8
  Content-Length: 143
}}
    Content: {System.Net.Http.ObjectContent<RestAPI.Model.User>}
    Headers: {}
    Method: {POST}
    Properties: Count = 0
    RequestUri: {http://localhost:2468/api/Users}
    Version: {1.1}

HTTP內容：

{System.Net.Http.ObjectContent<RestAPI.Model.User>}
    Formatter: {System.Net.Http.Formatting.JsonMediaTypeFormatter}
    Headers: {Content-Type: application/json; charset=utf-8
Content-Length: 143
}
    ObjectType: {Name = "User" FullName = "RestAPI.Model.User"}
    Value: {RestAPI.Model.User}

編輯#2：

響應體：

    Id = 22, 
    Status = RanToCompletion, 
    Method = "{null}", 
    AsyncState: null
    CancellationPending: false
    CreationOptions: None
    Exception: null
    Id: 22
    Result: {Message:"The request is invalid.",
    ModelState:{"user.Username":["Unable to find a constructor to use for type ClAuP.RestAPI.Model.User. A class should either have a default constructor, one constructor with arguments or a constructor marked with the JsonConstructor attribute. Path 'Username', line 1, position 12."]}}"
    Status: RanToCompletion

Answer 1

錯誤消息說您需要一個默認構造函數來反序列化對象。 由於您添加了自定義構造函數，這意味着除非您明確將其放在那里，否則沒有空的默認構造函數。 所以你應該能夠添加

public User() { }

到您的 User 類並解決該錯誤。

Answer 2

為了能夠序列化和反序列化一個對象，您需要一個空的構造函數。

public class User
{
    // Add this
    public User()
    {
    }

    public User(string userName, string email, string password) : this(userName, email, password, null, null)
    {

    }

    public User(string userName, string email, string password, string Name, string firstName)
    {
        this.Username = userName;
        this.Email = email;
        this.Password = password;
        this.Name = Name;
        this.firstName = firstName;
    } 

    [...]
}

創建User類的實例后，它將通過公開給模型的公共屬性填充模型。 您已經擁有公共屬性，因此添加構造函數可以解決您的問題。

Answer 3

您必須將 [FromBody] 添加到您的方法並驗證您所指的 clace 沒有繼承“From Body”強制您讀取整個正文，如果它沒有找到請求的屬性，則返回 NULL [ResponseType (typeof (用戶))]公共異步任務

[ResponseType (typeof (User))]
Public asynchronous task <IHttpActionResult> PostUser ([FromBody]User user)