Question

我有循环运行，等待和其他事情的业务逻辑。当前，这在后面的代码中。

据我所知，这是错误的地方，应该将其放置在viewModel中（如果错误，请更正）。如果是这种情况，那么我应该在我的VM中有一个OnAppearing方法，如果是这样，应该如何将OnAppearing传递给视图模型？

当前，我的页面OnAppearing看起来像这样：

    protected async override void OnAppearing()
    {
        base.OnAppearing();
        Title = Settings.mode.Text() + " Deck";
        vm.LearnViewVisible = Settings.mode.IsLearn();
        vm.PracticeViewVisible = Settings.mode.IsPractice();
        vm.QuizViewVisible = Settings.mode.IsQuiz();
        vm.QuizStartViewVisible = false;

如果我要将大部分业务逻辑转移到ViewModel，那是否意味着所有这些都将转移到我在ViewModel中创建的OnAppearing（）方法？

Answer 1

其他方式是使用行为

...
<ContentPage.Behaviors>
    <behaviors:EventHandlerBehavior EventName="Appearing">
        <behaviors:InvokeCommandAction Command="{Binding PageAppearingCommand}" />
    </behaviors:EventHandlerBehavior>
    <behaviors:EventHandlerBehavior EventName="Disappearing">
        <behaviors:InvokeCommandAction Command="{Binding PageDisappearingCommand}" />
    </behaviors:EventHandlerBehavior>
</ContentPage.Behaviors>
...

Original

Answer 2

以下是我的解决方案示例

public partial class TaskDetailsPage : MvvmContentPage
{
    private readonly TaskDetailsViewModel _model;

    public TaskDetailsPage()
    {
        InitializeComponent();
        Shell.SetNavBarIsVisible(this, true);
        Shell.SetTabBarIsVisible(this, false);
        _model = BindingContext as TaskDetailsViewModel;
    }

    protected override string NavigationRoute => UniqeCodes.Routes.TaskDetailsPage;

    

    protected override void OnAppearing()
    {
        _model.Init();
    }
}

Answer 3

这就是我链接我的 Viewmodel 的方式。我建议使用以下方法设置 ViewModelBase：VModelActive 和 VModelInactive

背后的代码：

{
    "devDependencies": {
        "@fullhuman/postcss-purgecss": "^4.0.0",
        "@fullhuman/vue-cli-plugin-purgecss": "~4.0.2",
        "@vue/cli-plugin-babel": "~4.5.0",
        "@vue/cli-plugin-eslint": "~4.5.0",
        "@vue/cli-plugin-router": "~4.5.0",
        "@vue/cli-plugin-vuex": "~4.5.0",
        "@vue/cli-service": "~4.5.0",
        "@vue/compiler-sfc": "^3.0.0",
        "@vue/eslint-config-prettier": "^6.0.0",
        "autoprefixer": "^10.2.5",
        "babel-eslint": "^10.1.0",
        "eslint": "^6.7.2",
        "eslint-plugin-prettier": "^3.1.3",
        "eslint-plugin-vue": "^7.0.0-0",
        "node-sass": "^5.0.0",
        "postcss": "^8.2.8",
        "prettier": "^1.19.1",
        "sass-loader": "^10.1.1",
        "tailwindcss": "^2.0.3"
    }
}

查看模型

public partial class YourClass : ContentPage
    {
        ViewModelClass viewModelClass;
        public YourClass()
        {
            InitializeComponent();
            viewModelClass = new ViewModelClass();
            this.BindingContext = viewModelClass;                
        }

        protected override void OnAppearing()
        {
            base.OnAppearing();
            viewModelClass.VModelActive(this, EventArgs.Empty);
        }

        protected override void OnDisappearing()
        {
            base.OnDisappearing();
            viewModelClass.VModelInactive(this, EventArgs.Empty);
        }
    }

可以将OnAppearing传递给Xamarin Forms MVVM中的ViewModel吗？

3 个答案: