如何使用MvvmCross流畅的API将RecyclerView项目的TextView绑定到Android上ViewModel的属性？

Question

我在我的Xamarin Android项目中使用MvvmCross.我有一个用,我已经在它的布局文件分配一个项目模板.MvxActivityMvxRecyclerView

<MvxRecyclerView
    android:id="@+id/my_recycler_view"
    local:MvxItemTemplate="@layout/item_recycler_view" />

ViewModel非常简单,它只包含一个属性,用于保存要显示在以下内容中的数据RecyclerView:

public class MainViewModel : MvxViewModel
{
    private IEnumerable<ViewModelItem> _viewModelItems;
    public IEnumerable<ViewModelItem> ViewModelItems
    {
        get { return _viewModelItems; }
        set { SetProperty(ref _viewModelItems, value); }
    }    
}

通常,我喜欢尽可能多地使用MvvmCross流畅的API,因为隐式重构支持.所以在我的活动中,我绑定了这样的属性MvxRecyclerView:

var recyclerView = View.FindViewById<MvxRecyclerView>(Resource.Id.my_recycler_view);
var set = this.CreateBindingSet<MainView, MainViewModel>();
set.Bind(recyclerView)
    .For(v => v.ItemsSource)
    .To(vm => vm.ViewModelItems);
set.Apply();

到现在为止还挺好.现在,项目模板的布局文件基本上只包含TextView:

<LinearLayout>
    <TextView
        android:id="@+id/innerText" />
</LinearLayout>

我的ViewModelItem班级看起来像这样:

public class ViewModelItem
{
    public string Title { get; set; }
}

我现在的问题是,如何以及在何处使用流畅的API TextView.Text将ViewModelItem.Title属性绑定到属性？

我知道通过MvxBind在项目模板布局文件中提供属性,没有流畅的API很容易,但我真的更喜欢流畅的API解决方案.

Answer 1

继承自MvxRecyclerAdapter并为RecyclerView创建自定义适配器.覆盖OnCreateViewHolder并返回自定义ViewHolder.

public class MyAdapter : MvxRecyclerAdapter
{
    public MyAdapter(IMvxAndroidBindingContext bindingContext)
        : base(bindingContext)
    {
    }

    public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
    {
        var itemBindingContext = new MvxAndroidBindingContext(parent.Context, this.BindingContext.LayoutInflaterHolder);
        var view = this.InflateViewForHolder(parent, viewType, itemBindingContext);

        return new MyViewHolder(view, itemBindingContext);
    }
}

在此ViewHolder中,您可以使用Fluent API进行绑定.

public class MyViewHolder : MvxRecyclerViewHolder
{
    private readonly TextView textView;

    public MyViewHolder(View itemView, IMvxAndroidBindingContext context)
        : base(itemView, context)
    {
        this.textView = itemView.FindViewById<TextView>(Android.Resource.Id.Text1);

        this.DelayBind(() =>
        {
            var set = this.CreateBindingSet<MyViewHolder, ViewModelItem>();
            set.Bind(this.textView).To(x => x.Title);
            set.Apply();
        });
    }
}

在您的Activity中创建适配器并将其添加到RecyclerView:

var adapter = new MyAdapter((IMvxAndroidBindingContext)this.BindingContext);
recyclerView.Adapter = adapter;

并将您的项目绑定到您的适配器的ItemsSource:

set.Bind(this.adapter).For(x => x.ItemsSource).To(x => x.ViewModelItems);