列表框中的選定項目爲空我怎樣才能解決這個問題？

Question

我正在使用列表框系統，該列表框系統允許使用我的控制器中的刪除方法刪除系統中的練習。目前，當我選擇一個項目，然後點擊刪除它返回一個空的列表項目，並沒有對數據庫進行任何更改

目前我的代碼沒有產生任何錯誤，但當前設置了一些斷點後，看起來itemRemoveExercises當前爲null。所以我改了行RegimeItem item = model.RequestedExercises.FirstOrDefault(i => i.RegimeItemID == selected);到RegimeItem item = model.RequestedSelected...，現在我recieving錯誤'int' does not contain a definition for 'RegimeItemID' and no extension method 'RegimeItemID' accepting a first argument of type 'int' could be found

我希望發生的是選擇按下刪除按鈕時被刪除政權項目。

Controller.cs

[HttpGet] 
    public ActionResult ExerciseIndex(int id, UserExerciseViewModel vmodel) 
    { 

     //Session["UserExerciseViewModel"] = userExerciseViewModel; 
     User user = db.Users.Find(vmodel.UserID); 
     //User user = db.Users.Find(id); 
     //vmodel.UserID = user.UserID; 
     UserExerciseViewModel model = new UserExerciseViewModel { AvailableExercises = GetAllExercises(), RequestedExercises = ChosenExercises(user, vmodel) }; 
     Session["UserExerciseViewModel"] = model; 
     return View(model); 
    } 

    //Post 
    [HttpPost] 
    public ActionResult ExerciseIndex(UserExerciseViewModel model, string add, string remove, string send, int id, RegimeItem item) 
    { 
     // model = (UserExerciseViewModel)(Session["UserExerciseViewModel"]); 
     //model.UserID = user.UserID; 
     User user = db.Users.Find(model.UserID); 
     user.RegimeItems = model.RequestedExercises; 
     UserExerciseViewModel model2 = (UserExerciseViewModel)(Session["UserExerciseViewModel"]); 
     model.RequestedExercises = model2.RequestedExercises; 
     model.AvailableExercises = model2.AvailableExercises; 
     if (!string.IsNullOrEmpty(add)) 
      AddExercises(model, id); 
     else if (!string.IsNullOrEmpty(remove)) 
      RemoveExercises(model, id);    
     SaveState(model); 
     RestoreSavedState(model, user); 
     return View(model); 
    } 

    void SaveState(UserExerciseViewModel model) 
    { 
     model.SavedRequested = string.Join(",", model.RequestedExercises.Select(p => p.RegimeItemID.ToString()).ToArray()); 
     db.SaveChanges(); 
    } 

    void RemoveExercises(UserExerciseViewModel model, int id) 
    { 
     var userExerciseViewModel = (UserExerciseViewModel)(Session["UserExerciseViewModel"]); 
     foreach (int selected in model.RequestedSelected) 
     { 
      RegimeItem item = model.RequestedExercises.FirstOrDefault(i => i.RegimeItemID == selected); 
      if (item != null) 
      { 
       User user = db.Users.Find(id); 
       model.RequestedExercises.Remove(item); 
      } 
     } 
     db.SaveChanges(); 
    } 

    void AddExercises(UserExerciseViewModel model, int id) 
    { 
     var userExerciseViewModel = (UserExerciseViewModel)(Session["UserExerciseViewModel"]); 
     foreach (int selected in model.AvailableSelected) 
     { 
      if (model.AvailableSelected != null) 
      { 
       User user = db.Users.Find(id); 
       user.RegimeItems.Add(new RegimeItem() 
       { 
        RegimeExercise = (this.GetAllExercises().FirstOrDefault(i => i.ExerciseID == selected)) 
       }); 
      } 
     } 
     db.SaveChanges(); 
     //RedirectToAction("ExerciseIndex"); 
    } 

    void RestoreSavedState(UserExerciseViewModel model, User user) 
    { 
     user.RegimeItems = model.RequestedExercises; 
     //get the previously stored items 
     if (!string.IsNullOrEmpty(model.SavedRequested)) 
     { 
      string[] exIds = model.SavedRequested.Split(','); 
      var regimeItems = ChosenExercises(user, model).Where(p => exIds.Contains(p.RegimeItemID.ToString())); 
      model.RequestedExercises.AddRange(regimeItems); 
     } 
     db.SaveChanges(); 
    } 

    private List<Exercise> GetAllExercises() 
    { 
     return db.Exercises.ToList(); 
    } 

    private List<RegimeItem> ChosenExercises(User user, UserExerciseViewModel model) 
    { 
     return db.Users 
    .Where(u => u.UserID == user.UserID) 
    .SelectMany(u => u.RegimeItems) 
    .ToList(); 
    } 

模型（CS）

public class User 
    { 
     public int UserID { get; set; } 
     public ICollection<RegimeItem> RegimeItems { get; set; } 
     public User() 
     { 
      this.RegimeItems = new List<RegimeItem>(); 
     } 
    } 
    public class RegimeItem 
    { 
     public int RegimeItemID { get; set; } 
     public Exercise RegimeExercise { get; set; } 
    } 

ViewModel.cs

public class UserExerciseViewModel 
{ 
    public List<Exercise> AvailableExercises { get; set; } 
    public List<RegimeItem> RequestedExercises { get; set; } 
    public int? SelectedExercise { get; set; } 
    public int[] AvailableSelected { get; set; } 
    public int[] RequestedSelected { get; set; } 
    public string SavedRequested { get; set; } 
} 

View.cshtml（僅段）

 <input type="submit" name="remove" 
      id="remove" value="<<" /> 
    </td> 
    <td valign="top"> 
     @Html.ListBoxFor(model => model.RequestedSelected, new MultiSelectList(Model.RequestedExercises, "RegimeItemID", "RegimeExercise.Name", Model.RequestedSelected)) 
    </td> 

Answer 1

你的問題的事實，你正在試圖將一個int值的RegimeItemID財產梗;看看下面的例子：

public int[] RequestedSelected { get; set; } 
RegimeItem item = model.RequestedSelected.FirstOrDefault(i => i.RegimeItemID == selected); 

基本上你告訴LINQ到嘗試使用int迭代器int[]陣列的.RegimeItemID。

如果我沒有記錯的話你的結構，你應該改變

RegimeItem item = model.RequestedSelected.FirstOrDefault(i => i.RegimeItemID == selected); 

到：

RegimeItem item = model.RequestedExercises[selected]; 

在循環

。

foreach (int selected in model.RequestedSelected) 
//foreach (var item in new ArrayList(model.RequestedExercises.RegimeItemID)) 
{ 
    RegimeItem item = model.RequestedExercises[selected]; 
    if (item != null) 
    { 
     model.RequestedExercises.Remove(item); 
     db.SaveChanges(); 
    } 
} 

編輯：

新的信息提供：在問題的代碼是逸岸正確的代碼，但問題在於這看起來應該更多的線沿線的RestoreSavedState方法：

void RestoreSavedState(UserExerciseViewModel model, User user) 
{ 
    user.RegimeItems = model.RequestedExercises; 
    //get the previously stored items 
    if (!string.IsNullOrEmpty(model.SavedRequested)) 
    { 
     string[] exIds = model.SavedRequested.Split(','); 
     var regimeItems = ChosenExercises(user, model).Where(p => exIds.Contains(p.RegimeItemID.ToString())); 
     model.RequestedExercises.AddRange(regimeItems); 
    } 
}