Can't remove last item from ICollection
I am trying to remove the last item from the collection, but it doesn't work. I am using MVC 4 and EF Code first. I generate all views and controllers and add a module with a checkbox that each checkbox is checked for one type collection object.
these are my models:
{
public class Efekt
{
public int ID { get; set; }
public string Symbol { get; set; }
public string Typ { get; set; }
[DataType(DataType.MultilineText)]
public string Opis { get; set; }
[DataType(DataType.MultilineText)]
public string Odnosnik
{
get
{
(...)
}
// set;
}
public virtual ICollection<Obszarowe> EfektyObszarowe { get; set; }
public virtual ICollection<Przedmiot> Przedmioty { get; set; }
public Efekt(){
}
public Efekt(string symbol,string opis,string odnosnik){
(...)
}
}
}
{
public class Obszarowe
{
public int ID { get; set; }
public string Symbol { get; set; }
public string Typ { get; set; }
[DataType(DataType.MultilineText)]
public string Opis { get; set; }
[DataType(DataType.MultilineText)]
public string Odnosnik
{
get
{
(...)
}
// set;
}
public virtual ICollection<Efekt> EfektyKierunkowe { get; set; }
public Obszarowe(){
}
public Obszarowe(string symbol, string opis, string odnosnik)
{
(...)
}
}
}
and editing functions in efektcontroller
public ActionResult Edit(int id = 0)
{
Efekt efekt = db.Efekts.Find(id);
if (efekt == null)
{
return HttpNotFound();
}
EfektyObszarowe(efekt);
return View(efekt);
}
private void EfektyObszarowe(Efekt efekt)
{
var allObszarowe = db.EfektyObszarowe;
var kierunkoweObszarowe = new HashSet<int>(efekt.EfektyObszarowe.Select(c => c.ID));
var viewModel = new List<KierunkoweObszarowe>();
foreach (var obszar in allObszarowe)
{
viewModel.Add(new KierunkoweObszarowe
{
ID = obszar.ID,
Symbol = obszar.Symbol,
Wybrany = kierunkoweObszarowe.Contains(obszar.ID)
});
}
ViewBag.Courses = viewModel;
}
//
// POST: /Efekt/Edit/5
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit(int id , string[] selectedCourses)
{
Efekt efekt = db.Efekts.Find(id);
if (ModelState.IsValid)
{
UpdateObszarowe(selectedCourses, efekt);
db.Entry(efekt).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
EfektyObszarowe(efekt);
return View(efekt);
}
private void UpdateObszarowe(string[] selectedCourses, Efekt instructorToUpdate)
{
if (selectedCourses == null)
{
instructorToUpdate.EfektyObszarowe = new List<Obszarowe>();
return;
}
var selectedCoursesHS = new HashSet<string>(selectedCourses);
var instructorCourses = new HashSet<int>
(instructorToUpdate.EfektyObszarowe.Select(c => c.ID));
//var temp = db.Efekts.Find(instructorToUpdate.ID);
///////// Obszarowe ob;
foreach (var course in db.EfektyObszarowe)
{
if (selectedCoursesHS.Contains(course.ID.ToString()))
{
if (!instructorCourses.Contains(course.ID))
{
instructorToUpdate.EfektyObszarowe.Add(course);
/*ob = db.EfektyObszarowe.Find(Int32.Parse(course));
instructorToUpdate.EfektyObszarowe.Add(ob);
*/
}
}
else
{
if (instructorCourses.Contains(course.ID))
{
instructorToUpdate.EfektyObszarowe.Remove(course);
}
}
}
}
When I unchecked the box that says "Obszarowe" it is ok, remove the item from the collection and I only see checked objects, but when I uncheck it, there is no difference :( sorry for my english
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You do...
instructorToUpdate.EfektyObszarowe = new List<Obszarowe>();
But you get instructorToUpdate
with ...
Efekt efekt = db.Efekts.Find(id);
This means that the collection is EfektyObszarowe
not loaded and therefore not tracked for changes. Therefore, you need to load the collection when you receive Efekt
:
Efekt efekt = db.Efekts.Include(e => e.EfektyObszarowe).Single(e.ID == id);
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