I have quite a few fragments, that are 90% common in layout. And because I really like layout from code (I never create XIBs for iOS anymore), I thought: lets do the same for Android. That was not as easy as I thought it would be. The trouble is in MvvmCross, and after scouring the web for solutions, only hints pointing to the solution can be found.
The problem: when the fragment is displayed, and I perform the binding, I get all messages the source property cannot be found because it tries to bind to a null-object.
Unable to bind: source property source not found Cirrious.MvvmCross.Binding.Parse.PropertyPath.PropertyTokens.MvxPropertyNamePropertyToken on null-object
The layout is displayed on screen, the ViewModel is set, the bindingcontext is set (both created by myself, because that was not done automatically).
I suspect something is done in inflation to 'register' the created controls, and because I do not use inflation, they are not registered. I read in other questions about the MvxBindingContextStackRegistration, watched the sources for that. Second cause might be the bindingcontext itself: somehow it is not handled automatically, and that points to something necessary missing beging called in the below code.
I might have done some strange thing, because this is the final attempt to get it working:
public class IndexTocFragment : MvxFragment
{
// two statics to save on typing
public static int WRAP = ViewGroup.LayoutParams.WrapContent;
public static int FILL = ViewGroup.LayoutParams.FillParent;
public LinearLayout NewVerticalLinearLayout(Orientation orientation, Boolean fillparent) {
var ll = new LinearLayout (Activity) { Orientation = orientation };
ll.LayoutParameters = new ViewGroup.LayoutParams (FILL, fillparent ? FILL : WRAP);
return ll;
}
public new IndexTocViewModel ViewModel { get { return base.ViewModel as IndexTocViewModel; } set { base.ViewModel = value; } }
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
base.OnCreateView (inflater, container, savedInstanceState);
var layout = NewVerticalLinearLayout (Orientation.Vertical, true);
if (ViewModel == null)
ViewModel = Mvx.IocConstruct<IndexTocViewModel> ();
BindingContext = new MvxAndroidBindingContext (Activity, new MvxSimpleLayoutInflater(inflater));
using (new MvxBindingContextStackRegistration<IMvxAndroidBindingContext>(((IMvxAndroidBindingContext) this.BindingContext)))
{
//var layout = NewVerticalLinearLayout (Orientation.Vertical, true);
layout.SetBackgroundColor (Color.ParseColor("#FFFFFF"));
var titlelayer = NewVerticalLinearLayout (Orientation.Horizontal, false);
titlelayer.LayoutParameters.Height = 40;
var title = new TextView (Activity) { LayoutParameters = new ViewGroup.LayoutParams (FILL, FILL) };
title.SetTextColor (Color.ParseColor ("#212121"));
var titlebutton = new Button (Activity) { LayoutParameters = new ViewGroup.LayoutParams (WRAP, FILL) };
titlelayer.AddView (title);
titlelayer.AddView (titlebutton);
layout.AddView (titlelayer);
var twobuttonlayer = NewVerticalLinearLayout (Orientation.Horizontal, false);
twobuttonlayer.LayoutParameters.Height = 40;
var twobuttonklein = new Button (Activity) { LayoutParameters = new ViewGroup.LayoutParams (FILL, WRAP) };
twobuttonklein.Text = "Klein";
twobuttonklein.SetBackgroundResource (Resource.Drawable.kleingrootbutton);
var twobuttongroot = new Button(Activity){ LayoutParameters = new ViewGroup.LayoutParams (FILL, WRAP) };
twobuttongroot.Text = "Middel/groot";
twobuttongroot.SetBackgroundResource (Resource.Drawable.kleingrootbutton);
twobuttonlayer.AddView (twobuttonklein);
twobuttonlayer.AddView (twobuttongroot);
layout.AddView (twobuttonlayer);
var zoekvak = new EditText (Activity) { LayoutParameters = new ViewGroup.LayoutParams (FILL, WRAP) };
zoekvak.Hint = "Zoek in inhoudsopgave";
layout.AddView (zoekvak);
var emptytext = new TextView (Activity) { LayoutParameters = new ViewGroup.LayoutParams (FILL, WRAP),
Text = "Er zijn geen resultaten." };
emptytext.SetBackgroundColor (Color.ParseColor ("#BBAA00"));
layout.AddView (emptytext);
var listadapter = new BindableExpandableListAdapter(this.Activity, (IMvxBindingContext) BindingContext);
var list = new BindableExpandableListView (Activity, null, listadapter) { LayoutParameters = new ViewGroup.LayoutParams (FILL, FILL) };
list.SetMinimumHeight (50);
list.ItemTemplateId = Resource.Layout.indextocsectionlistitem;
list.GroupTemplateId = Resource.Layout.indextocitem;
list.SetGroupIndicator (null);
list.SetBackgroundColor (Color.ParseColor ("#AAAA00"));
layout.AddView (list);
this.DoBind += () => {
var bs = this.CreateBindingSet<IndexTocFragment, IndexTocViewModel> ();
if (ViewModel == null) {
Console.WriteLine ("ERROR ViewModel not set");
}
if (BindingContext == null) {
Console.WriteLine ("ERROR BindingContext not set");
}
bs.Bind (title).For (x => x.Text).To (vm => vm.IndexTitle);
// the following title displays some data from the ViewMode, and that works OK.
Console.WriteLine("Index title value: "+ViewModel.IndexTitle);
bs.Bind (twobuttongroot).For ("Click").To (vm => vm.SwitchKleinGrootCommand);
bs.Bind (twobuttonklein).For ("Click").To (vm => vm.SwitchKleinGrootCommand);
bs.Bind (zoekvak).For (x => x.Text).To (vm => vm.SearchText);
bs.Bind (emptytext).For (x => x.Text).To (vm => vm.TextForEmptyList);
bs.Bind (listadapter).For(x => x.ItemsSource).To(vm => vm.Chapters);
bs.Apply ();
};
// the next binding was never called
//this.DelayBind (() => {
//
//});
}
//var view = this.BindingInflate(Resource.Layout.IndexTocView, null);
Console.WriteLine ("LAYOUT RETURNED");
return layout;
}
private Action DoBind;
public override void OnResume()
{
// doing the binding here to make sure everything should have been set,
but it is of course not the logical location
base.OnResume();
Console.WriteLine ("RESUMING");
if (DoBind != null)
DoBind ();
}
}
For now I will create a fragment layout with everyting I need, and hide the elements that are not needed, that will probably work. But I hope I can use creating views from code.
Thanks for helping.
BTW: the code from the activity and presenter is the custom presenter code taken from the fragments example in MvvmCross. Binding in code for Android: MVVMCross for android - how to do binding in code? Pushing a context on the stack: MvvmCross: How to programmatically construct an MvxListView with custom adapter?
