Question

I really search the internet and could not find a answer.

Its hard for me to describe what i try to do. Maybe that is the reason i
could not find a answer on Stackoverflow and Google.

I have a ListBox in my Page which is bound to a ObservableCollection<Model>.
This Model has a property with a Id of another model. There is also
a Dictionary<int,SecondModel> containing the realted second models.

I could not add a property with the second model to the first model because this is a third party library.

Is it possible to get the Name property from the realated SecondModel using the collection?

Text="{Binding ???}"

Sample

public class Model
{
    public int Id { get; set; }
    public int SecondModelId { get; set; }
}

public class SecondModel
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class SomeOtherModel
{
    public Dictionary<int,SecondModel> SecondModelCollection{ get; set; }
}

Answer 1

If you cannot play with the guts of Model class, I ll suggest wrapping the two models in a something like:

public class JoinedModel
{
  public Model FirstModel{ get; set; }
  public Model SecondModel{ get; set; }
}

 var secondModelCollection = SomeOtherModel.SecondModelCollection.Values;

 var joinedCollection = from model in firstModelCollection
                              join secondModel in secondModelCollection 
                              on model.SecondModelId equals secondModel.Id
                              select new JoinedModel() { FirstModel = model, SecondModel = secondModel };

You can set the joinedCollection as the data source instead of the firstModelCollection which isgiven as ObservableCollection<Model> in the question.

Then in the binding, you can do a two level binding like Text="{Binding SecondModel.Name}"

… tho, I am assuming you can change the datasource of your view, I hope you can 🙂