android 的 MVVMCross - 如何在代码中进行绑定? [英] MVVMCross for android - how to do binding in code?

问题描述

我想使用 MVVMCross，但是对于我的 android 应用程序，我还想使用其他库(滑动菜单和操作栏)，这些库要求我从他们的自定义类继承我的活动类.这阻止了我继承 MvxActivity，但我注意到在 iOS 的 MVVMCross 中，您可以在代码中完成所有绑定(请参阅 https://github.com/slodge/NPlus1DaysOfMvvmCross/blob/master/N-00-FirstDemo/FirstDemo.Touch/Views/FirstView.cs)

var set = this.CreateBindingSet();set.Bind(textEditFirst).To(vm => vm.FirstName);set.Bind(textEditSecond).To(vm => vm.LastName);set.Bind(labelFull).To(vm => vm.FullName);设置.应用()；

Android 有没有办法做到这一点?

解决方案

是的 - 如果需要，您可以在 Android 中使用流畅的绑定.

完全相同的代码应该可以工作.

您需要使用 FindViewById() 获取对 ui 控件的引用，然后才能绑定它们.

例如，在 TipCalc 中，您可以添加已识别的控件，例如:

然后使用以下方法实现绑定:

protected override void OnViewModelSet(){SetContentView(Resource.Layout.View_Tip);var edit = this.FindViewById(Resource.Id.FluentEdit);var set = this.CreateBindingSet();set.Bind(edit).To(vm => vm.SubTotal);设置.应用()；//对于非默认属性，使用 'For'://set.Bind(edit).For(ed => ed.Text).To(vm => vm.SubTotal);//你也可以使用://.WithConversion("converter", "可选参数")//.OneTime()、.OneWay() 或 .TwoWay()}

此外，您可以通过以下方式将任何 FooActivity 转换为数据绑定 MvxFooActivity:

• 从 FooActivity 继承以提供来自 EventSourceFooActivity 中的生命周期事件的事件
• 从 EventSourceFooActivity 继承以在 MvxFooActivity 中提供数据上下文
• 然后您可以在从 MvxFooActivity 继承的活动中编写代码

要查看所需的代码，请参阅:

• https://github.com/slodge/MvvmCross/blob/v3/Crillous/Cirrious.MvvmCross.Droid.Fragging/MvxEventSourceFragmentActivity.cs
• https://github.com/slodge/MvvmCross/blob/v3/Crillous/Cirrious.MvvmCross.Droid.Fragging/MvxFragmentActivity.cs

您将在所有 mvx 改编的活动中看到相同的代码 - MvxActivity、MvxTabActivity ......这里有一点剪切和粘贴，但尽可能多的代码放在共享扩展方法中.

在以前的版本中，人们使用这种技术来绑定 monogame 和 google 广告活动 - 例如，请参阅 在 MvvmCross monodroid Activity 中插入 Monogame 视图

I want to use MVVMCross, however for my android application I also want to use other libraries (sliding menu and action bar) which require me to inherit my activity classes from their custom class. This prevents me from inheriting MvxActivity, but I noticed that in MVVMCross for iOS, you can do all your bindings in code (see https://github.com/slodge/NPlus1DaysOfMvvmCross/blob/master/N-00-FirstDemo/FirstDemo.Touch/Views/FirstView.cs)

var set = this.CreateBindingSet<FirstView, FirstViewModel>();
set.Bind(textEditFirst).To(vm => vm.FirstName);
set.Bind(textEditSecond).To(vm => vm.LastName);
set.Bind(labelFull).To(vm => vm.FullName);
set.Apply();

Is there any way to do that in Android?

解决方案

Yes - you can use fluent bindings in Android if you want to.

Exactly the same code should work.

You'll need to get references to the ui controls using FindViewById<Type>(), then you can bind them.

For example, in TipCalc you can add identified controls like:

<EditText
    android:id="@+id/FluentEdit"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:inputType="number"
    android:textSize="24dp"
    android:gravity="right"
    />

and then implement binding using:

protected override void OnViewModelSet()
{
    SetContentView(Resource.Layout.View_Tip);

    var edit = this.FindViewById<EditText>(Resource.Id.FluentEdit);

    var set = this.CreateBindingSet<TipView, TipViewModel>();
    set.Bind(edit).To(vm => vm.SubTotal);
    set.Apply();

    // for non-default properties use 'For':
    // set.Bind(edit).For(ed => ed.Text).To(vm => vm.SubTotal);

    // you can also use:
    //   .WithConversion("converter", "optional parameter")
    //   .OneTime(), .OneWay() or .TwoWay()
}

Additionally, you can convert any FooActivity into a data-binding MvxFooActivity by:

• inheriting from FooActivity to provide events from lifetime events in an EventSourceFooActivity
• inheriting from EventSourceFooActivity to provide a datacontext in an MvxFooActivity
• you can then write your code inside activities inheriting from MvxFooActivity

To see, the code required, see:

• https://github.com/slodge/MvvmCross/blob/v3/Cirrious/Cirrious.MvvmCross.Droid.Fragging/MvxEventSourceFragmentActivity.cs
• https://github.com/slodge/MvvmCross/blob/v3/Cirrious/Cirrious.MvvmCross.Droid.Fragging/MvxFragmentActivity.cs

You'll see the same code in all the mvx adapted Activities - MvxActivity, MvxTabActivity, ... There is a little cut-and-paste here, but as much code as possible is place in shared extension methods.

In previous versions, people have used this technique to bind monogame and google ads activities - eg see Insert a Monogame view inside MvvmCross monodroid Activity

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