CODEWITHSUNDEEP
wpfbinding
baozi
baozi

Reputation: 709

How to indirectly set a binding?

I've seen enough examples with binding to property A with a datacontext where A exists in the viewModel class. Now what if in the viewModel I do not have any property A, instead I create some calss B that contains property A, then how to set up a binding here?

Let's say in xaml<TextBlock Text="{Binding Bid}"..> and In the viewModel's constructor I set up 

Quote b = new Quote();
HttpClient.QuoteMap.Add(1,b);
HttpClient.Socket.reqMktdata(1,contract,..)

So b keeps updating its Bid and Ask... The thing is I don't see how to set a binding to b's Bid. For listview or DataGrid I can see how to do it as there's a property called itemsource to specify the data binding source and for each column different property is bind to any property if needed.

Upvotes: 0

Views: 263

Answers (2)

ΩmegaMan
ΩmegaMan

Reputation: 31616

In your viewmodel create a property A which has the notify event on its change, but get the data from the B instance. If B has INotifyPropertyChanged, then subscribe to those changes and when B event fires that a change has occurred, post the notified change for your property A such as

OnPropertyChanged("A");

That way you can have related data which exists elsewhere but still updates the view accordingly.

This will update when the B property Data changes, to the property A on the MVVM.

class MyMVVM : INotifyPropertyChanged
{
        private TheBClass B { get;  set { OnPropertyChanged("A"); } }

        public string A
        {
            get { return B.Data; }
            set { OnPropertyChanged("A"); }
        }


   public MVVM(TheBClass bInstance;)
   {
      B = bInstance;

      B.PropertyChanged += (sender, args) =>
      {
          if (args.PropertyName == "Data")
             OnPropertyChanged("A");
      };

   }
}

Upvotes: 0

paparazzo
paparazzo

Reputation: 45096

The class itself needs to be a property. 

<TextBlock Text="{Binding Path=MyClassToBind.PublicProperty}"

private MyClass myClass = new MyClass();
public MyClass MyClassToBind 
{    get { return  myClass; }  }

Upvotes: 1

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