Question

一旦新特性在文本Box中分类,我怎么能够使数据具有约束性更新?

我正在学习世界森林论坛的约束性,现在我已经陷入一个简单的(全心全意)问题。

I have a simple FileLister class where you can set a Path property, and then it will give you a listing of files when you access the FileNames property. Here is that class:

class FileLister:INotifyPropertyChanged {
    private string _path = "";

    public string Path {
        get {
            return _path;
        }
        set {
            if (_path.Equals(value)) return;
            _path = value;
            OnPropertyChanged("Path");
            OnPropertyChanged("FileNames");
        }
    }

    public List<String> FileNames {
        get {
            return getListing(Path);
        }
    }

    private List<string> getListing(string path) {
        DirectoryInfo dir = new DirectoryInfo(path);
        List<string> result = new List<string>();
        if (!dir.Exists) return result;
        foreach (FileInfo fi in dir.GetFiles()) {
            result.Add(fi.Name);
        }
        return result;
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string property) {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) {
            handler(this, new PropertyChangedEventArgs(property));
        }
    }
}

Im利用FileLister这一非常简单的参考资料:

<Window x:Class="WpfTest4.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfTest4"
    Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <local:FileLister x:Key="fileLister" Path="d:	emp" />
    </Window.Resources>
    <Grid>
        <TextBox Text="{Binding Source={StaticResource fileLister}, Path=Path, Mode=TwoWay}"
        Height="25" Margin="12,12,12,0" VerticalAlignment="Top" />
        <ListBox Margin="12,43,12,12" Name="listBox1" ItemsSource="{Binding Source={StaticResource ResourceKey=fileLister}, Path=FileNames}"/>
    </Grid>
</Window>

The binding is working. If I change the value in the textbox and then click outside of it, the listbox contents will update (as long as the path exists).

问题是,一旦出现新的特征,我就希望得到更新,而不是等到案文箱失去重点。

How can I do that? Is there a way to do this directly in the xaml, or do I have to handle TextChanged or TextInput events on the box?

Answer 1

在你具有约束力的文本箱中,你必须做的是<代码>UpdateSourceTrigger=PropertyChanged。

Answer 2

页: 1 UpdateSourceTrigger property to PropertyChanged

<TextBox Text="{Binding Source={StaticResource fileLister}, Path=Path, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
         Height="25" Margin="12,12,12,0" VerticalAlignment="Top"/>

Answer 3

Without C#, it s enough in XAML for TextBox, not for class. So, monitoring the property of TextBlock, where writing length of TextBox: Binding Text.Length

<StackPanel>
  <TextBox x:Name="textbox_myText" Text="123" />
  <TextBlock x:Name="tblok_result" Text="{Binding Text.Length, ElementName=textbox_myText}"/>
</StackPanel>

友情链接