实体框架多线程

Question

i want to remove entities on a background thread but we can not delete entities on another thread that it has be created on so how can i do that and keep the ui responding? i'm tying to use the backgroundworker class here is the code

void deletePeriodWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            Thread.Sleep(3000);
            List<Period> selectedPeriods = e.Argument as List<Period>;

            foreach (Period period in selectedPeriods)
            {
                while (period.Transactions.Count > 0)
                {
                    Transaction transaction = period.Transactions[0];
                    this.Dispatcher.Invoke(new Action(() => context.Transactions.Remove(transaction)), 
                        System.Windows.Threading.DispatcherPriority.Normal);
                }

                this.Dispatcher.Invoke(new Action(() => context.Periods.Remove(period)), 
                    System.Windows.Threading.DispatcherPriority.Normal);
            }
            this.Dispatcher.Invoke(new Action(() => context.SaveChanges()),
                    System.Windows.Threading.DispatcherPriority.Normal);
        }

Answer 1

Don't use 'foreach' to delete entities. When you delete a entity,the source is changed, it may throw an exception. Use 'for' instead. And why you delete it in a new thread?UI will be updated when all of the delete operations are finished.

try like this:

UI(List): itemsource={Binding LstTest}

background:

deletePeriodWorker_DoWork() {

        List<Period> selectedPeriods = e.Argument as List<Period>;

        foreach (Period period in selectedPeriods)
        {
            while (period.Transactions.Count > 0)
            {
                //operation
            }

            //ui updating
            this.Dispatcher.Invoke(new Action(() => LstTest.Remove(period)), 
                System.Windows.Threading.DispatcherPriority.Normal);

            //EF updating
            context.Periods.Remove(period);

        }

        //context savechanges

}