How to set the selected item in MvxSpinner

Question

I have an MvxSpinner associated with a List<PhotoCategory> , thus:

 <Mvx.MvxSpinner style="@style/Spinners" android:id="@+id/photoCategorySpinner" android:prompt="@string/photoCategory_prompt" local:MvxBind="ItemsSource PhotoCategories; SelectedItem SelectedPhotoCategory; Visibility ShowPhotoFields, Converter=Visibility" local:MvxDropDownItemTemplate="@layout/spinner_photocategories" local:MvxItemTemplate="@layout/item_photocategory" /> 

SelectedPhotoCategory to which the SelectedItem parameter is PhotoCategory is also PhotoCategory . When this screen is in “update mode”, the ViewModel sets the SelectedPhotoCategory to PhotoCategory, where PhotoCategoryId matches the one in the SQLite database. However, when the counter is displayed, the default value is displayed (which I add to the PhotoCategories property, PhotoCategory = 0, CategoryName = "[Select Category]"). The only fix I found is the code (which works fine) is added to the view:

 protected override void OnCreate(Bundle bundle) { base.OnCreate(bundle); SetContentView(Resource.Layout.PhotoView); //If we're in Update mode, select the relevant photo category in the spinner: PhotoViewModel photoViewModel = (PhotoViewModel)ViewModel; if (photoViewModel.ScreenMode == Constants.ScreenMode.Update) { MvxSpinner photoCategorySpinner = FindViewById<MvxSpinner>(Resource.Id.photoCategorySpinner); int itemPosition = 0; int selectedPhotoCategoryId = photoViewModel.SelectedPhotoCategory.PhotoCategoryId; foreach (PhotoCategory photoCategory in photoViewModel.PhotoCategories) { if (photoCategory.PhotoCategoryId == selectedPhotoCategoryId) { photoCategorySpinner.SetSelection(itemPosition); } itemPosition++; } } 

I also tried using the GetPosition method for MvxSpinner.Adapter, but this always returns -1 for PhotoCategoryId, CategoryName or SelectedPhotoCategory as the parameter value.

What am I missing?

Answer 1

Binding

  SelectedItem SelectedPhotoCategory 

should set this for you - and should use Equals to find the right item to select in the counter.

This certainly works in the latest code when testing using the SpinnerViewModel at https://github.com/slodge/MvvmCross-Tutorials/tree/master/ApiExamples

I know that there has recently been an error related to using == versus Equals in one of the bindings - but I don't think this affects the counter (see https://github.com/slodge/MvvmCross/issues/309 ).