如何设置一个视图模型绑定与ReactiveUI一个TextBox？ [英] How to setup a ViewModel binding for a TextBox with ReactiveUI?

问题描述

有关某种原因，我不能让我的文本/属性绑定到工作自动与无UI。

For some reason I can't get my textbox/property binding to work "automatically" with Reactive UI.

我的DataContext的设置是这样的：

My DataContext is setup like this:

我的视图模型是为后面的MainWindow.xaml.cs的code设置：

My ViewModel is setup in the code behind for the MainWindow.xaml.cs:

public MainWindowViewModel ViewModel { get; protected set; }

public MainWindow()
{
    ViewModel = new MainWindowViewModel();
}

在我的WPF MainWindow.xaml我在DataContext和有这样一个文本框元素：

In my WPF MainWindow.xaml I have the DataContext and the have a textbox element like this:

（其它性能ommitted）

(Other properties ommitted)

<Window x:Name="Window">
    <Grid DataContext="{Binding ViewModel, ElementName=Window}">
        <StackPanel x:Name="ContentGrid" Grid.Row="1">
            <TextBox Name="Password" Text="{Binding Password, Mode=TwoWay}" />
            ...

在MainWindowViewModel我有一个属性，现场是这样的：

In the MainWindowViewModel I have a property and field like this:

string _PasswordConfirmation;

public string PasswordConfirmation
{
    get { return _PasswordConfirmation; }
    set { this.RaiseAndSetIfChanged(x => x.PasswordConfirmation, value); }
}

我也有一个命令，就是设置是这样的：

I also have a command that is setup like this:

var canHitOk = this.WhenAny(
    x => x.Password,
    x => x.PasswordConfirmation,
    (pass, confirm) => (pass.Value == confirm.Value && pass.Value.Length > 3));

OkCommand = new ReactiveCommand(canHitOk);

正如您可以猜到，我也有密码确认文本/属性设置也和一个按钮（密码确认文本框有同样的问题）的命令集。由于字段/属性组合都从未在视图模型更新，按钮从未启用。

As you can guess, I also have the password confirmation textbox/property setup too, and the command set for a button (The password confirmation TextBox has the same problem). Since the field/property combos are never updated in the ViewModel, the button is never enabled.

我调试并确认该视图模型绑定到XAML，但文本永远不会在字段/属性组合在文本框输入时更新。

I debugged and confirmed that the ViewModel is bound to the XAML, but the text never gets updated in the field/property combos when typing in the TextBoxes.

我看着在样本WP7应用GitHub的回购，他们手动绑定的KeyUp 事件来设置在属性/字段中的文本。如果我遵守这个约定，我有这个在我的MainWindow.xaml：

I looked at the sample WP7 application in the GitHub repo and they manually bind the KeyUp event to set the text in the text in the property/field. If I follow this convention, I have this in my MainWindow.xaml:

Password.KeyUp += (o, e) =>
{
    ViewModel.Password = Password.Text;
};

但是，这是正确的方式做到这一点？我以为无UI会处理的结合，因为我已经看到了在其他MVVM框架，除非我错了。是否有更简单的方法？

But is that the right way to do it? I thought Reactive UI would handle the binding as I've seen in other MVVM frameworks, unless I'm mistaken. Is there an easier way?

更新

正如保罗·贝茨在他回答的评论中指出的，您可以启用绑定通过增加该属性的绑定自动更新：

As Paul Betts pointed out in the comments in his answer, you can enable the binding to automatically update by adding this property to the binding:

UpdateSourceTrigger=PropertyChanged

这将使TextBox元素是这样的：

which would make the TextBox element look like this:

<TextBox Name="Password" Text="{Binding Password, UpdateSourceTrigger=PropertyChanged}" />

推荐答案

的问题是，WP7文本框不更新其上的KeyUp自动绑定 - 这是与每一个MVVM框架伤心的问题。

The problem is that WP7 TextBox doesn't Update its binding automatically on KeyUp - this is a problem with every MVVM framework sadly.

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