我目前正在开发一个列表框,它需要具有从列表框中删除/删除项目以及最终数据库的功能。当在列表框中选择一个项目(RegimeItem)时,按下删除按钮,该项目将从数据库中删除,这就是我想要发生的事情。
控制器的RemoveExercises
方法中foreach语句的RequestedSelected部分当前为null,我想知道的是我如何才能使它不是?据我所知,当在列表框中选择未被识别为RequestedSelected
控制器
[HttpGet]
public ActionResult ExerciseIndex(int? id, UserExerciseViewModel vmodel)
{
User user = db.Users.Find(id);
UserExerciseViewModel model = new UserExerciseViewModel { AvailableExercises = GetAllExercises(), RequestedExercises = ChosenExercises(user, vmodel) };
user.RegimeItems = model.RequestedExercises;
return View(model);
}
[HttpPost]
public ActionResult ExerciseIndex(UserExerciseViewModel model, string add, string remove, string send, int id, RegimeItem regimeItem)
{
User user = db.Users.Find(id);
user.RegimeItems = model.RequestedExercises;
RestoreSavedState(model);
if (!string.IsNullOrEmpty(add))
AddExercises(model, id);
else if (!string.IsNullOrEmpty(remove))
RemoveExercises(model, id);
SaveState(model);
return View(model);
}
void SaveState(UserExerciseViewModel model)
{
model.SavedRequested = string.Join(",", model.RequestedExercises.Select(p => p.RegimeItemID.ToString()).ToArray());
model.AvailableExercises = GetAllExercises().ToList();
}
void RemoveExercises(UserExerciseViewModel model, int? id)
{
foreach (int selected in model.RequestedSelected)
{
RegimeItem item = model.RequestedExercises.FirstOrDefault(i => i.RegimeItemID == selected);
if (item != null)
{
User user = db.Users.Find(id);
user.RegimeItems.Remove(item);
}
}
db.SaveChanges();
//RedirectToAction("ExerciseIndex");
}
void RestoreSavedState(UserExerciseViewModel model)
{
model.RequestedExercises = new List<RegimeItem>();
//get the previously stored items
if (!string.IsNullOrEmpty(model.SavedRequested))
{
string[] exIds = model.SavedRequested.Split(',');
var exercises = GetAllExercises().Where(p => exIds.Contains(p.ExerciseID.ToString()));
model.AvailableExercises.AddRange(exercises);
}
}
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
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; }
}
视图模型
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; }
}
查看(仅限细分)
<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>
更新:感谢Chris的帮助,我在控制器上取得了进展,并且我也更新了视图。它仍然没有删除单个项目,它返回一个空白列表,它也不会保存到数据库中。
答案 0 :(得分:1)
你永远不会坚持任何事情。除非你在某个地方拨打SaveChanges
,否则你正在做的所有事情都会在下一次请求时消失。