Strange error on Updating

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C#

C#4.0

entity-framework

Hello everybody!

First of all sorry about my bad English.
I am a starting programmer and I have following problem.

With EF and a generic repository I can do an Insert and Delete without any problem.
The problem is invoked when I do an update on the same database and same object.

The error message is the following:
System.InvalidOperationException
Collection was modified; enumeration operation may not execute.

I have done some research but I can't solve of figuring out what is the problem...
The strange thing is that I use the same context as the select / or insert (so the collection must be the same).

Has anyone an idea?

Many thanks in advance!

the code:


this is the method in the generic repository

public static T AddOrUpdate<T>(this DbContext context, T entity)
           where T : class
       {
           if (context == null) throw new ArgumentNullException("context");
           if (entity == null) throw new ArgumentNullException("entity");

           if (IsTransient(context, entity))
           {

               context.Set<T>().Add(entity);
           }
           else
           {
               context.Set<T>().Attach(entity);  //here I get the error
               context.Entry(entity).State = EntityState.Modified;
           }
           return entity;
       }

This is my damagecore

public static Result NewDamage(Context ctx, CarDamage _newCarDamage)//Damage _newDamage)
        {
            
            
            GenericRepository<CarDamage> carCamageRepo = new GenericRepository<CarDamage>(ctx);
            carCamageRepo.AddOrUpdate(_newCarDamage);
            
            ctx.SaveChanges();
            
            return null;
        }

code behind the button

private void save_Click(object sender, RoutedEventArgs e)
     {
         double invAmount;
         if (NoEmptyFieldsCheck() == false)
         {
             MessageBox.Show("Gelieve alle velden in te vullen", "Schade", MessageBoxButton.OK, MessageBoxImage.Warning);
             return;
         }
         if (DamageOverviewCheck() == false)
         {
             MessageBox.Show("Gelieve minstens 1 schade onderdeel toe te voegen", "Schade", MessageBoxButton.OK, MessageBoxImage.Warning);
             return;
         }
         if (Double.TryParse(invoiceAmount.Text, out invAmount)== false)
         {
             MessageBox.Show("Geef een geldig factuurbedrag","Schade", MessageBoxButton.OK, MessageBoxImage.Warning);
             return;
         }

        // Damage newDamage = new Damage();

        // CarDamage newCarDamage = new CarDamage() { Car = (Car)carComboBox.SelectedItem, ActualValue= true };
         carDamage.Car = (Car)carComboBox.SelectedItem;
         carDamage.ActualValue = true;

         newDamage.DamageDate = damageDate.SelectedDate ?? DateTime.Today;
         newDamage.DamageState = (DamageState)damageStateComboBox.SelectedItem;
         newDamage.DamageCauser = damageCauser.Text;
         newDamage.InvoiceAmount = (float)invAmount;
         newDamage.PaymentFranchiseDriver = paymentFranchiseDriver.IsChecked.Value;
         newDamage.PaymentOk = paymentOk.IsChecked.Value;
         newDamage.DamageOverview = damageOverview;

         if (accident.IsChecked == true)
         {
             Accident newAccident = new Accident();
             newAccident.AccidentFileDate = fileDate.SelectedDate ?? DateTime.Today;
             newAccident.FileState = (FileState)fileStateComboBox.SelectedItem;
             newAccident.AccidentDescription = accidentDescriptionTxtBox.Text;
             newDamage.Accident = newAccident;

         }

         if (files.Count > 0)
         {


             foreach (var file in files)
             {
                 Document doc = new Document();

                 string fileExtention = Path.GetExtension(file);
                 string fileName = Path.GetFileNameWithoutExtension(file);
                 string originalFilePath = Path.GetFullPath(file);
                 doc.FileDestination = @"C:\Users\Jeffry\Desktop\document.carma\" + doc.DocumentID + fileExtention;

                 doc.OriginalFileName = fileName;
                 doc.AdditionDate = DateTime.Today;
                 File.Copy(originalFilePath, doc.FileDestination);





             }
             newDamage.Document = docList;
         }

         carDamage.CarID = (int)carComboBox.SelectedValue;
         carDamage.ActualValue = true;
         carDamage.Damage = newDamage;
         DamageCore.NewDamage(mainWindow.ctx, carDamage);

         id = newDamage.DamageID; //getting id of last added damage (needed to go to documents for getting right documents)

     }

Added 15/04/2014


ObjectID is passed to constructor

private void viewDetail_Click(object sender, RoutedEventArgs e)
       {
           CarDamage carDamage = (CarDamage)damageLV.SelectedItem;
           DamagePage damagePage = new DamagePage(mainWindow, carDamage.DamageID);
           mainWindow.MainFrame.Navigate(damagePage);
       }

Constructor of the page

public DamagePage(MainWindow main, int damageId)
       {
           mainWindow = main;
           mainWindow.SetTitle("Detail schade");
           InitializeComponent();
           AddData();
           carDamage = DamageCore.GetDamage(mainWindow.ctx, damageId);
           //carDamage.CarDamageID = damageId;
           FillDataOnForm(carDamage);
       }

Code where i get CarDamage object and fill the form... is invoked by the constructor

private void FillDataOnForm(CarDamage carDamage)
      {
          damageDate.SelectedDate = carDamage.Damage.DamageDate;
          carComboBox.SelectedValue = carDamage.CarID;
          damageStateComboBox.SelectedValue = carDamage.Damage.DamageStateID;
          damageCauser.Text = carDamage.Damage.DamageCauser;
          invoiceAmount.Text = carDamage.Damage.InvoiceAmount.ToString("0.00");

          paymentFranchiseDriver.IsChecked = carDamage.Damage.PaymentFranchiseDriver;
          paymentOk.IsChecked = carDamage.Damage.PaymentOk;
          accident.IsChecked = false;
          if (carDamage.Damage.AccidentID != 0)
          {
              accident.IsChecked = true;
              fileDate.SelectedDate = carDamage.Damage.Accident.AccidentFileDate;
              fileStateComboBox.SelectedValue = carDamage.Damage.Accident.FileStateID;
              accidentDescriptionTxtBox.Text = carDamage.Damage.Accident.AccidentDescription;
          }
          damageOverview = carDamage.Damage.DamageOverview;

          damagesLV.ItemsSource = null;
          damagesLV.ItemsSource = damageOverview;
          docList = carDamage.Damage.Document;
          id = carDamage.DamageID;



      }

Update 17/04/2014

Generic update

public void Update(T entity)
        {
            var entry = _context.Entry(entity);
            if (entry.State == EntityState.Detached)
            {
                _context.Set<T>().Attach(entity);
                entry = _context.Entry(entity);
            }
            entry.State = EntityState.Modified;
        }

update 23/04/2014

I still have the same problem...

Here is my add or update method... (which also doesn't work... :( )

public static T AddOrUpdate<T>(this DbContext context, T entity)
            where T : class
        {
            if (context == null) throw new ArgumentNullException("context");
            if (entity == null) throw new ArgumentNullException("entity");
            
            if (IsTransient(context, entity))
            {
                
                context.Set<T>().Add(entity);
            }
            else
            {
                // original
                context.Set<T>().Attach(entity);

// here i Get an error... and i don't know why...

//errormessage: Collection was modified; enumeration operation may not execute !!!!!!!!???????


                context.Entry(entity).State = EntityState.Modified;


                //test
                //context.Entry<T>(entity).State = EntityState.Modified;
                //context.Entry(entity).State = EntityState.Modified;
            }
            return entity;
        }