AppointmentSaving is invoked twice, but only on every other edit

[Rian]

I have a case where the event handler that handles AppointmentSaving is invoked twice, but only every other time. It goes like this:

 

1) Find a calendar event

2) Drag the edge of the event to make it wider

3) Find a second event, and drag *that* event wider. AppointmentSaving will be called twice.

4) Repeat every other time. (2, 4, 6, 8, etc. with no end)

 

Here's the XAML setting up the event handler:

 

<i:EventTrigger
    EventName="AppointmentSaving">
    <vp:EventToCommandAction
        PassEventArgsToCommand="True"
        Command="{Binding HandleDowntimeSavingCommand, Mode=OneWay}" />
</i:EventTrigger>

 

Here's the event handler itself:

 

public ICommand HandleDowntimeSavingCommand => DelegateCommand.Create<AppointmentSavingEventArgs>(HandleDowntimeSaving);
internal void HandleDowntimeSaving(AppointmentSavingEventArgs eventArgs)
{
    var downtime = (DowntimeViewModel)eventArgs.Appointment;
    var numExceptionsRemoved = RemovePointlessExceptions(downtime);
    var numExceptionsConverted = ConvertExceptionsToIsolatedDowntimes(downtime);
    if (numExceptionsRemoved > 0 && numExceptionsConverted == 0)
    {
        eventArgs.Cancel = true;
    }
}

 

DelegateCommand.Create is used in literally thousands of places; it's not the source of the bug. If I set a breakpoint on the first line of the event handler, it will be hit twice, but only on every second edit.

[Dilyan Traykov]

Hello Rian,

I tried to reproduce the behavior you've described but was unable to do so. I'm attaching the sample project I've used for the purpose. Can you please have a look at it and let me know how I can modify it in order to replicate the aforementioned issue?

I'm looking forward to your reply.

Regards,
Dilyan Traykov
Progress Telerik