CODEWITHSUNDEEP
c#wpfmvvminotifypropertychanged
Kitson88
Kitson88

Reputation: 2940

Using MVVM, how can I implement INotifyPropertyChanged on a predefined collection of objects?

I think this question could of already been answered, which if this is the case I will delete immediately. I'm new to WPF (and new to C# really) and I'm trying as hard as possible to follow MVVM but I'm really struggling with finding a way to NOT implement INotifyPropertyChanged on my Model.

My Model contains a collection of predefined objects which are created from another reference. Within the Model, I have properties which are updated as and when the Task is completed.

CustomObject - API

public class CustomObject
{
  private string _myTaskOutput;

  public CustomObject()
  {
     _myTaskOutput = MyTaskMethod();
  }

   //MyTaskMethod()

  //Get & Setter for _myTaskOutput;
}

Util - API

 public static class Util
 {
     public IEnumerable<CustomObject> GenerateObjects()
     {
         var customObjectCollection = SomeHelperMethod();
         return customObjectCollection;
     }
 }

Model

   public class CustomObjectCollectionModel
   {
     private IEnumerable<CustomObject> _customObjectCollection;

     public CustomObjectCollectionModel()
     {
         _customObjectCollection = Util.GenerateObjects();
     }

     //Get & Setter for IEnumerable<CustomObject>
   }

The object reference does not change so I believe having an ObservableCollection is out of the question (is this correct?) and implementing INotifyPropertyChanged on CustomObject works as intended but I understand this not the correct way of doing things.

Upvotes: 0

Views: 163

Answers (1)

mm8
mm8

Reputation: 169200

If CustomObject is some kind of domain or business object, you could wrap it in a view model class in your client application. So instead of binding to an ObservableCollection<CustomObject> you bind to an ObservableCollection<CustomObjectWrapper> where CustomObjectWrapper is a client-specific class that implements the INotifyPropertyChanged interface (provided that you actually need to provide change notifications in your UI).

You will indeed have to create a CustomObjectWrapper for each CustomObject that you receive from your service API - you could do this in your view model class - but at the same time you don't have to pollute your business objects with client-specific code. Binding directly to domain-specific business objects is rarely useful.

Upvotes: 1

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