How to disable context menu item via coding in asp.net code behind file.

protected void Scheduler_BeforeEventRender(object sender, BeforeEventRenderEventArgs e)
{

if (condition)
{
e.ContextMenuClientName = "DayPilotMenu1";
}

}

You can store your condition in e.value example : e.Value.StartsWith("p")

See also the documentation on event customization:

http://doc.daypilot.org/scheduler/event-customization/

The data source object properties can be reached using e.DataItem:

protected void DayPilotScheduler1_BeforeEventRender(object sender, BeforeEventRenderEventArgs e)
{
  string type = (string) e.DataItem["type"];
  
  if (type == "type1") {
    e.ContextMenuClientName = "menu2";
  }
}

You can also use e.Tag and DataTagFields -> these values will be available even for events restored from ViewState.

You have to define create a new DayPilotMenu object for each menu type. Set the ClientObjectName and use the value for e.ContextMenuClietName.