关于xamarin.forms：Xamarin Forms自定义控件数据绑定问题

Xamarin Forms custom control data binding issue

我有一个简单的自定义控件，但无法让公开的可绑定 Command 属性正常工作。

设置如下：MainPage.xaml 承载 CustomControl.xaml(下方的米色区域)。 CustomControl 包含一个标签和一个按钮。 MainPage 包含 CustomControl、Entry、Label 和一个 Button。所有控件都绑定到 MainPageViewModel 中的 CustomControlText 属性。因此，随着该属性的更改，所有控件都应更新。

它主要工作...

请看下面的演示视频。我单击 MainPage 上的按钮，所有控件都会更新，包括自定义控件。当我更改条目值时，所有字段都会更新。但是，单击"从 CustomControl 增加"没有任何作用。它应该调用 MainViewModel.

中的 SubmitCommand2

enter

MainPage.xaml

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MainPage.xaml.cs

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public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
}
}

MainPageModel.cs

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public class MainPageModel : FreshBasePageModel
{
public MainPageModel() { }

public string CustomControlText { get; set; }

private int _index = 0;

public Command SubmitCommand
{
get
{
return new Command(() =>
{
_index++;
CustomControlText = $"Hello World {_index}";
});
}
}

public Command SubmitCommand2
{
get
{
return new Command(() =>
{
_index++;
_index++;
CustomControlText = $"Hello World {_index}";
});
}
}

public override void Init(object initData)
{
CustomControlText ="Hello World";

base.Init(initData);
}
}

CustomControl.xaml

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CustomControl.xaml.cs

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[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class CustomControl : ContentView
{
public CustomControl()
{
TextData ="";

InitializeComponent();
}

public static readonly BindableProperty TextDataProperty = BindableProperty.Create(
propertyName:"TextData",
returnType: typeof(string),
declaringType: typeof(CustomControl),
defaultBindingMode: BindingMode.TwoWay,
defaultValue:"");

public string TextData
{
get { return base.GetValue(TextDataProperty).ToString(); }
set { base.SetValue(TextDataProperty, value); }
}

public static readonly BindableProperty CommandProperty = BindableProperty.Create(
propertyName:"Command",
returnType: typeof(Command),
declaringType: typeof(CustomControl),
defaultBindingMode: BindingMode.OneWay);

public Command Command { get; set; }
}

CustomControl的Command属性也应该用base.GetValue和base.SetValue实现，和TextData一样。

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public partial class CustomControl : ContentView
{
...

public static readonly BindableProperty CommandProperty =
BindableProperty.Create(
propertyName: nameof(Command),
returnType: typeof(ICommand),
declaringType: typeof(CustomControl),
defaultBindingMode: BindingMode.OneWay,
defaultValue: default(ICommand));

public ICommand Command
{
get => (ICommand) GetValue(CommandProperty);
set => SetValue(CommandProperty, value);
}
}