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    <p>All the creation-related issues can be resolved with introduction of <a href="http://en.wikipedia.org/wiki/Factory_method_pattern" rel="nofollow">factory design pattern</a>. The factory will take care of creating <strong>view models</strong> basing on model that was provided. </p> <pre><code>public class MainWindowViewModel { private List&lt;Model&gt; _NamesModel; private ObservableCollection&lt;ViewModel&gt; _NamesViewModel; private IViewModelFactory factory; public void MainWindowViewModel(IViewModelFactory factory) { //Lets pretend we have a service that returns a list of models _NamesModel = Service.Request(); _NamesViewModel = factory.CreateNamesViewModels(_NamesModel); } public ObservableCollection&lt;ViewModel&gt; NamesViewModel { get { return _NamesViewModel; } } } </code></pre> <p>What is more, you could even get rid of <code>Service</code> dependency in view model and move it to the factory itself, thus reducing the need to keep model in view model (admittedly though, removal of model might not work in more complex scenarios):</p> <pre><code>public ObservableCollection&lt;ViewModel&gt; CreateNamesViewModels() { var models = Service.Request(); return new ObservableCollection(models.Select(m =&gt; new ViewModel(m))); } </code></pre> <p>Also, your main window view model can expose <a href="http://msdn.microsoft.com/en-us/library/system.windows.input.icommand.aspx" rel="nofollow"><code>commands</code></a> that utilize factory to create any new instances. This way, no model is leaking to view and also no creation details are exposed (since commands will hide actual implementation).</p>
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    1. COAh, this is a really clean implementation, I like it! I've been essentially having to encorporate alot of the factories abilites into my MainWindowViewModel (I've got methods in the MainWindowViewModel for deletion, adding, etc.). Thanks for this!
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      1. USAdam Kewley
    2. COI'm trying this implementation right now. With it, would you reccomend that the MainWindowViewModel doesn't handle Models at all? That is to say, the Factory handles the models and just gives the MainWindowViewModel the necessary ViewModels for handling? In that case, should the MainWindowViewModel ViewModel collections have CollectionChanged handlers that utilize the factory?
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      1. USAdam Kewley
    3. CO@AdamKewley: Like I noted, when model is complex you might want to keep model around. Unless that's the case, I'd get rid of model in view model. `PropertyChanged` and `ObservableCollection`s are usually enough.
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