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POGet notified when properties change in the Model
 

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    <p>There seems to be conflicting thoughts on whether <code>INotifyPropertyChanged</code> should be implemented in the Model or not. I think that it should be implemented in the ViewModel, but I can't figure out how it would be accomplished. There are plenty of mentions of this same idea all over stackoverlow.com ( <a href="https://stackoverflow.com/questions/6922130/in-mvvm-model-should-the-model-implement-inotifypropertychanged-interface">In MVVM model should the model implement INotifyPropertyChanged interface?</a>, <a href="https://stackoverflow.com/questions/772214/in-mvvm-should-the-viewmodel-or-model-implement-inotifypropertychanged">In MVVM should the ViewModel or Model implement INotifyPropertyChanged?</a>), but I can't find any example to show how to do it.</p> <p>Let's say for example I have a model Person:</p> <pre><code>Public Person { public int Age { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public void NameChange( string newName ); } </code></pre> <p>How would I implement the ViewModel so that changes in <code>Age</code>, <code>FirstName</code>, or <code>LastName</code> are all recognized?</p> <pre><code>Public PersonViewModel : INotifyPropertyChanged { Person _person; public event PropertyChangedEventHandler PropertyChanged; void OnPropertyChanged(string propertyName) { if(this.PropertyChanged != null) this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } //ctor, Properties, etc... } </code></pre> <p><strong><em>EDIT - Clarification:</em></strong></p> <p>So <strong>without changing the Person model</strong> how do I modify the ViewModel to get notified of the updates? </p> <p>Is that even possible? If not, how are those that subscribe to the "INPC in the model is <em>baaaad</em>" get notified of changes in the model?</p>
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    1. COAs a practical matter, how often are changes to individual fields going to happen that are initiated WITHIN the model?
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    2. COI am not familiar with C#, but would you be able to use the Observer design pattern to handle this?
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    3. CO@Rich - I don't have a specific model in mind. I have written models that implement the INotifyPropertyChanged, but it always felt wrong. I've read that many people feel that it is wrong as well, so my question mainly was to figure out how those people managed their models.
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