wpf - 如何让数据绑定(bind)使用简单的 MVVM 结构

Question

在得到正确答案后，我想我应该更新它以显示工作代码供人们将来引用:

主窗口.xaml

<Grid>
    <Grid.Resources>
        <local:ValueConverters x:Key="ValueConverters"></local:ValueConverters>
    </Grid.Resources>
    <TextBox Text="{Binding Text, UpdateSourceTrigger=PropertyChanged}">
        <TextBox.Style>
            <Style>
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Path=Text,Converter={StaticResource ValueConverters}}" Value="True">
                        <Setter Property="TextBox.Foreground" Value="Red"></Setter>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </TextBox.Style>
    </TextBox>
</Grid>

主窗口.xaml.cs

public partial class MainWindow : MetroWindow
{
     private readonly DataBindingViewModel _vm = new DataBindingViewModel();

    public MainWindow()
    {
        InitializeComponent();
        DataContext = _vm;
    }
}

DataBindingViewModel.cs

public class DataBindingViewModel : INotifyPropertyChanged
{
    private string _text;

    public string Text
    {
        get
        {
            return this._text;
        }
        set
        {
            this._text = value;
            if (null != PropertyChanged)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs("Text"));
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

值(value)转换器

public class ValueConverters : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (null != value)
        {
            if (value.ToString() == "1")
                return true;
        }
        return false;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return null;
    }
}

以上现在有效:)

Answer 1

在 MainWindow 的 XAML 中，DataContext 设置为 ValueConverters 的一个实例:

<Window.DataContext>
    <local:ValueConverters/>
</Window.DataContext>

这似乎没有意义。您应该将其替换为

<Window.DataContext>
    <local:DataBindingViewModel/>
</Window.DataContext>

您不必在 MainWindow 的构造函数中再次设置 DataContext，但可能仍会像这样分配私有(private)字段(供以后使用):

private readonly DataBindingViewModel _vm;

public MainWindow()
{
    InitializeComponent();
    _vm = (DataBindingViewModel)DataContext;
}

或者，根本不要在 XAML 中设置 DataContext，并在后面的代码中创建它，如下所示:

private readonly DataBindingViewModel _vm = new DataBindingViewModel();

public MainWindow()
{
    InitializeComponent();
    DataContext = _vm;
}