如何將EntityFramework模型保存在其內部？

Question

我有一個模型，稱爲用戶（從我的數據庫派生），我在部分類中添加方法，允許用戶對象執行維護類型的工作。

舉個例子，我想我的應用程序與其他數據庫更新用戶的SupervisorID在其數據庫中比對：

public partial class User 
{ 
    DatabaseEntities db = new DatabaseEntities(); 
    OtherEntities otherDB = new CommonEntities(); 

     public void UpdateSupervisor() 
     { 
      // Lookup the Supervisor's Username in the other Database: 
      string supervisorUsername = (from x in otherDB.vwEmployees 
           join y in otherDB.vwEmployees on x.Supervisor_EID equals y.Employee_ID 
           where x.User_ID == searchUsername 
           select y.User_ID).FirstOrDefault(); 

      // Update the database to record the Supervisor of this staff member: 
      this.SupervisorUserID = (from x in db.Users 
            where x.ADUsername == supervisorUsername 
            select x.UserID).FirstOrDefault(); 

      // At this point, this.SupervisorUserID stores the correct int, but the following command doesn't save any changes. 
      db.SaveChanges(); 
     } 
} 

代碼工作，除了db.SaveChanges（）不保存任何事情（沒有錯誤）。

的方法被稱爲這個類的外部，作爲登錄處理的一部分：

public class Login { 
// Connect to the database: 
DatabaseEntities db = new DatabaseEntities(); 

User currentUser = new User(); 

// Do some stuff... 

// Update the user's supervisor: 
currentUser.UpdateSupervisor(); 
} 

任何想法？

感謝，

羅素

Answer 1

你的類裏db對象是從一個在你的程序是調用此方法不同。另外，您的用戶對象可能不存在於數據庫中。所以，它不像設置屬性然後保存那麼簡單。

你將不得不在你的類裏使用你的db對象，然後相應地進行更新或添加。

public partial class User 
{ 
    DatabaseEntities db = new DatabaseEntities(); 
    OtherEntities otherDB = new CommonEntities(); 

     public void UpdateSupervisor() 
     { 
      // Lookup the Supervisor's Username in the other Database: 
      string supervisorUsername = (from x in otherDB.vwEmployees 
             join y in otherDB.vwEmployees on x.Supervisor_EID equals y.Employee_ID 
             where x.User_ID == searchUsername 
             select y.User_ID).FirstOrDefault(); 

      // Update the database to record the Supervisor of this staff member 
      this.SupervisorUserID = (from x in db.Users 
            where x.ADUsername == supervisorUsername 
            select x.UserID).FirstOrDefault(); 

      // Find user in DBContext using your primary key... 
      var user = db.Users.Find(this.ID); 
      if (user != null) 
      { 
       // User exists in database, update id 
       user.SupervisorUserID = this.SupervisorUserID; 
      } 
      else 
      { 
       // User does not exist in database 
       db.Users.Add(this); 
      } 
      db.SaveChanges(); 
     } 
} 

Answer 2

萬一別人遇到這一點 - 我能夠保存用戶部分類中的一個用戶，通過創建用戶內部用戶：

public partial class User 
{ 
    DatabaseEntities db = new DatabaseEntities(); 
    OtherEntities otherDB = new CommonEntities(); 

     public void UpdateSupervisor() 
     { 
      // Lookup the Supervisor's Username in the other Database: 
      string supervisorUsername = (from x in otherDB.vwEmployees 
           join y in otherDB.vwEmployees on x.Supervisor_EID equals y.Employee_ID 
           where x.User_ID == searchUsername 
           select y.User_ID).FirstOrDefault(); 

      // Update the database to record the Supervisor of this staff member: 
      this.SupervisorUserID = (from x in db.Users 
            where x.ADUsername == supervisorUsername 
            select x.UserID).FirstOrDefault(); 
      // NEW CODE: 
      // Create a new user inside the User class, set to the current User by ID: 
      User tempUser = db.Users.Find(this.UserID); 
      tempUser.SupervisorUserID = this.SupervisorUserID; 
      db.SaveChanges(); 
     } 
} 

我希望這是有幫助的人。 :-)

Russell