我有很多片段，在布局中 90% 是常见的。因为我真的很喜欢代码布局（我不再为 iOS 创建 XIB），所以我想：让我们为 Android 做同样的事情。这并不像我想象的那么容易。问题出在 MvvmCross 中，在网上搜索解决方案后，只能找到指向解决方案的提示。
问题：当显示片段并执行绑定时，我收到所有消息，源属性无法找到，因为它试图绑定到空对象。
Unable to bind: source property source not found Cirrious.MvvmCross.Binding.Parse.PropertyPath.PropertyTokens.MvxPropertyNamePropertyToken on null-object
布局显示在屏幕上，设置了 ViewModel，设置了绑定上下文（都是我自己创建的，因为这不是自动完成的）。
我怀疑在通货膨胀中做了一些事情来“注册”创建的控件，并且因为我不使用通货膨胀，所以它们没有被注册。我阅读了有关 MvxBindingContextStackRegistration 的其他问题，并查看了相关来源。第二个原因可能是 bindingcontext 本身：不知何故，它没有自动处理，这表明在下面的代码中调用了一些必要的缺失 beging。
我可能做了一些奇怪的事情，因为这是让它工作的最后尝试：
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 ();
}
}
现在我将创建一个包含我需要的所有内容的片段布局，并隐藏不需要的元素，这可能会起作用。但我希望我可以使用从代码创建视图。
感谢您的帮助。
顺便说一句：来自活动和演示者的代码是从 MvvmCross 中的片段示例中获取的自定义演示者代码。Android 代码中的绑定：Android 的MVVMCross - 如何在代码中进行绑定？ 在堆栈上推送上下文：MvvmCross：如何使用自定义适配器以编程方式构造 MvxListView？