WPF: How to make Calls to Dispatcher.Invoke() Synchronous?

问题

In my MVVM based Wix Managed Bootstrapper application, while handling different events, I'm trying to show the user a view to get some input. It looks like Burn events are executing Asynchronously because using Dispatcher.Invoke(), it is skipping or passing by the view and hitting the last event, i.e not waiting for this input task to finish.

Here is the event handler which needs to finish before hitting last one:

Please note that when MessageBox.Show is popped, it waits until we close it. While debugging, I see it actually switched to MissingSourceView and loaded MissingSourceViewModel, but then while skipping it, and executes ApplyComplete();

BootstrapperApplication.ResolveSource += (sender, e) => {
                        System.Windows.Forms.MessageBox.Show("Inside ResolveSource");

                     WixBootstrapperData.CurrentDispatcher.Invoke(((Action)(() =>
                        {
                            WixBootstrapperData.CurrentViewModel = new MissingSourceViewModel(WixBootstrapperData, InfoMessage);
                        })));
                    };


BootstrapperApplication.ApplyComplete += (sender, e) =>
            {               
                WixBootstrapperData.BootstrapperApplicationModel.FinalResult = e.Status;
                WixBootstrapperData.CurrentDispatcher.Invoke((Action)(() =>
                {
                  InfoMessage = AppResource.MsgFinished;
                  WixBootstrapperData.CurrentViewModel = new FinishViewModel(WixBootstrapperData, InfoMessage);
                }
                ));
            };

I guess, I should use await and async with ResolveSource(), but I face errors like:

Error CS1061 'BaseViewModel' does not contain a definition for 'GetAwaiter' and no extension method 'GetAwaiter' accepting a first argument of type 'Task' could be found (are you missing a using directive or an assembly reference?)

Any idea how to make it wait for finishing inside ResolveSource() and then jump to wherever it wants?

回答1:

Use this, and please tell if this solves your problem.

        WixBootstrapperData.CurrentDispatcher.Invoke(((Action)(() =>
        {
           Task.Factory.StartNew(() => {
              WixBootstrapperData.CurrentViewModel = new MissingSourceViewModel(WixBootstrapperData, InfoMessage);
           }).RunSynchronously();
        })));

来源：https://stackoverflow.com/questions/39839155/wpf-how-to-make-calls-to-dispatcher-invoke-synchronous

标签

wpf

asynchronous

mvvm

wix

bootstrapper