使用 MultiBinding 绑定元素

发布于 2024-08-06 16:04:20 字数 702 浏览 14 评论 0 原文

我有一个登录表单，其中包含用户名文本框和密码框。

我希望仅当两个字段都包含值时才启用“确定”按钮。

我有一个转换器，可以检查所有字符串是否为空或为空。

我在 Convert 方法的第一行放置了一个断点，只有当 MenuItem 初始化时，它才会停止，即当我更改文本时，它不会停止。

下面的示例效果很好，问题是当我更改文本时不会触发多重绑定；它仅在初始化表单时绑定：

<!--The following is placed in the OK button-->
<Button.IsEnabled>
    <MultiBinding Converter="{StaticResource TrueForAllConverter}">
        <Binding ElementName="tbUserName" Path="Text"/>
        <Binding ElementName="tbPassword" Path="Password"/>
    </MultiBinding>
</Button.IsEnabled>

我认为问题是当远程绑定源更改时您不会收到通知（例如，没有设置 UpdateTargetTrigger="PropertyChanged" 的选项。

任何想法？

原文

I have a login form that contains a username textbox and a password box.

I want the ok button to be enabled only when both the fields contain a value.

I have a converter that check for all the strings if they're null or empty.

I placed a breakpoint on the first line of the Convert method, and it stops only when the MenuItem initializes, afterwords, i.e. when I change the text it doesn't.

The following example works good, the problem is that the multibinding is not triggered when i change the text; it's only bound when initializing the form:

<!--The following is placed in the OK button-->
<Button.IsEnabled>
    <MultiBinding Converter="{StaticResource TrueForAllConverter}">
        <Binding ElementName="tbUserName" Path="Text"/>
        <Binding ElementName="tbPassword" Path="Password"/>
    </MultiBinding>
</Button.IsEnabled>

I think the issue is that you don't get notified when the remote binding source is changed (e.g. there is no an option to set UpdateTargetTrigger="PropertyChanged".

Any ideas?

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夏日落 2024-08-13 16:04:20

我建议你研究一下命令绑定。命令可以根据某些条件（即用户名和密码不为空）自动启用或禁用您的登录按钮。

public static RoutedCommand LoginCommand = new RoutedCommand();

private void CanLoginExecute(object sender, CanExecuteRoutedEventArgs e)
{
    e.CanExecute = !string.IsNullOrEmpty(_userInfo.UserName) && !string.IsNullOrEmpty(_userInfo.Password);
    e.Handled = true;
}

private void LoginExecute(object sender, ExecutedRoutedEventArgs e)
{
    MessageBox.Show("Loging in...");
    // Do you login here.
    e.Handled = true;
}

XAML 命令绑定看起来像这样

<TextBox Text="{Binding UserName, UpdateSourceTrigger=PropertyChanged}" />
<TextBox Text="{Binding Password, UpdateSourceTrigger=PropertyChanged}" />
<Button Command="local:LoginWindow.LoginCommand" >Login</Button>

注册命令

<Window.CommandBindings>
    <CommandBinding Command="local:LoginWindow.LoginCommand" CanExecute="CanLoginExecute" Executed="LoginExecute" />
</Window.CommandBindings>

在 XAML 中或在后面的代码中

public LoginWindow()
{
    InitializeComponent();

    CommandBinding cb = new CommandBinding(LoginCommand, CanLoginExecute, LoginExecute);
    this.CommandBindings.Add(cb);
}

更多阅读此处。

I would suggest you look into command binding. A command can enable or disable your Login button automatically depending on some condition (ie. user name and password is not empty).

public static RoutedCommand LoginCommand = new RoutedCommand();

private void CanLoginExecute(object sender, CanExecuteRoutedEventArgs e)
{
    e.CanExecute = !string.IsNullOrEmpty(_userInfo.UserName) && !string.IsNullOrEmpty(_userInfo.Password);
    e.Handled = true;
}

private void LoginExecute(object sender, ExecutedRoutedEventArgs e)
{
    MessageBox.Show("Loging in...");
    // Do you login here.
    e.Handled = true;
}

XAML command binding will look something like this

<TextBox Text="{Binding UserName, UpdateSourceTrigger=PropertyChanged}" />
<TextBox Text="{Binding Password, UpdateSourceTrigger=PropertyChanged}" />
<Button Command="local:LoginWindow.LoginCommand" >Login</Button>

To register the command in XAML

<Window.CommandBindings>
    <CommandBinding Command="local:LoginWindow.LoginCommand" CanExecute="CanLoginExecute" Executed="LoginExecute" />
</Window.CommandBindings>

Or in code behind

public LoginWindow()
{
    InitializeComponent();

    CommandBinding cb = new CommandBinding(LoginCommand, CanLoginExecute, LoginExecute);
    this.CommandBindings.Add(cb);
}