MVVMLight Messenger发送-暂停方法

Question

I'm converting a program to MVVM Light from Code Behind.

Part of this software, has to read in a CSV file from our bank, grab all the data, transform it, the copy it into a new CSV that will then get uploaded to our Accounting Software.

Using code behind, whilst reading the CSV, it would open up a new form if it was the first time that credit card had been uploaded, in order to set some defaults up, then once the defaults are set, it would continue processing.

I've been using the MessengerInstance to swap between forms and pass data between viewmodels. But I don't know how to send the message, pause the current running method until a message is sent back.

Send Message

     selectedCreditCard =
           _creditCardList.SingleOrDefault(x => x.CreditCardNumber == existingColumns[1]);
                 if (selectedCreditCard == null)
                 {
                     MessengerInstance.Send(Messaging.FormChanged.NewCreditCard);
                     MessengerInstance.Send(existingColumns[1], Messaging.MessengerTokens.
                  }

Receive Message

  public NewCreditCardViewModel()
    {
        Messenger.Default.Register<string>(this, Messaging.MessengerTokens.NewCreditCards, value => AccountName = value);

        SaveCommand = new RelayCommand(SaveNewCreditCard);
        RefreshCommand = new RelayCommand(RefreshVendorsAndReviewers);
        CreditCard = new VPCreditCard();
    }

Answer 1

If i understand you correctly

You want to keep this decoupled with messages, then just send a message back on OK from the defaults form to continue processing. Ie save the state and continue where you left off with the defaults

1. Process CSV part 1 (stop processing, save state, check for new cc)

   1.a - If new cc, send message to defaults form (if not new cc, Process CSV part 2 )

   1.b - Defaults opens, on OK, Send message back processing form

2. Receive finished defaults message, Process CSV part 2 (continue where left off)

The premise is you just have to break CSV processing in to 2 parts, 2 methods, and allow it to resume it self via its state