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Fully Embracing the Model-View-ViewModel Pattern in WPF

Posted By:      Posted Date: September 16, 2010    Points: 0   Category :WPF
I'm trying to get my head around the M-V-VM pattern as it is used with WPF. So far I have been successful in implementing this pattern but it's perfect (yet). There are a number of common UI workflows that I can't figure out how to implement in this pattern such as:1. A user clicks a button that should show a modal dialog box. Usually the VM has a command on it that the button is bound to and something executes. However, what needs to execute is a UI behavior (opening the dialog box). The VM should not open the dialog box (that would be wrong because the VM now has to know something about the UI). The Window or UserControl or Page inwhich the command was initiated should open the dialog box.2. A user clicks a button that executes a command on a VM. However, this is a long-running command and I'd like to show the WaitCursor during this operation. This is a UI function, not a VM function. Should the VM fire an event? And if so, how does the Xaml handle it?So, M-V-VM experts out there, what am I missing? Help me to see the light...Dave

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Model View ViewModel question



I´m playing around with XAML and MVVM, and have a question about the wiring between the model and the viewmodel:

If I have a model that updates its data on random times, what wiring is used between the model and the viewmodel to let the viewmodel know that the model has changed?.

Between the view and viewmodel a bindings and NotifyPropertyChanged would take care of this.


Trying to learn

MVVM Bind View Details to Model Via ViewModel when a Button clicked.


I have model called Car with prperties name,model,type,year.

I have implemeted the Viewmodel with same properties with OnpropertyChangedEvent including model object type Property.

I have a view usercontrol where textboxes for name, model and for year a combobox.

Whenever i fill the view i want to save those details into model via view model

I have written ICommand  Save which calls SaveCarDetails defined in viewmodel,  which is bind to a button in view ,All other texboxes text is bind to the properties of viewmodel properties.

When i put break point at ICommand SaveCommand and SaveCarDetails Function i could see the values filled from view.

But when i bind these details to another user control where listbox is placed and its itemsource property is set to Car property nothing but model object defined in the viewmodel.

I couldn't see the values binding via viewmodel to model.

Where as if i bind to textboxes in the listview i could see the values because i it's a dependency property.

Can any one please tell me what is the wrong i am doing here.




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