Xamarin MVVM Light ViewModelLocator 在 xaml 中设置 BindingContext

Posted 2023-04-13

【中文标题】Xamarin MVVM Light ViewModelLocator 在 xaml 中设置 BindingContext

【英文标题】：Xamarin MVVM Light ViewModelLocator setting BindingContext in xaml

【发布时间】：2016-12-26 15:09:41

【问题描述】：

我想通过 xaml 而不是后端代码来设置 BindingContext。目前我是这样分配的：

public partial class MainPage : ContentPage

    public MainPage()
    
        InitializeComponent();
        BindingContext = App.Locator.Main;
    

如何通过 Xaml 分配 BindingContext？我试过这样：

LoginPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="Codesign.DtpMobilePortable.Views.LoginPage" BindingContext="Binding LoginPage, Source=StaticResource ViewModelLocator"> 
  <StackLayout Spacing="20" Padding="50" VerticalOptions="Center">

    <Entry x:Name = "EntryUsername" Text="Binding EntryUsernameText" Placeholder = "Username"/>  
    <Entry x:Name = "EntryPassword" Text="Binding EntryPasswordText" Placeholder = "Password" IsPassword = "true"   />

    <Button x:Name = "ButtonLogin"
                        Text = "Binding LoginButtonText"
                        TextColor = "White"
                        BackgroundColor = "Binding LoginButtonColor" Command="Binding LoginCommand"/>    
  </StackLayout>
</ContentPage>

App.xaml

<?xml version="1.0" encoding="utf-8" ?>
<Application xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:viewModels="clr-namespace:Codesign.DtpMobilePortable.ViewModels;assembly=Codesign.DtpMobilePortable"
             x:Class="Codesign.DtpMobilePortable.Views.App">
<Application.Resources>
    <viewModels:ViewModelLocator
        x:Key="ViewModelLocator" />
</Application.Resources>
</Application>

但我收到有关 StaticResource 不存在的错误。

【参考方案1】：

您应在页面标题上定义StaticResources 名称空间。

类似的东西：

<ContentView xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:local="clr-namespace:Codesign.DtpMobilePortable;assembly=Codesign.DtpMobilePortable"
         xmlns:Vm="clr-namespace:Codesign.DtpMobilePortable.ViewModel;assembly=Codesign.DtpMobilePortable"
         x:Class="Codesign.DtpMobilePortable.Views.LoginPage"
         BindingContext="Binding LoginPage, Source=StaticResource ViewModelLocator"

在我的示例代码中，StaticResources 是在上面的 xmlnss:local 命名空间中定义的。