Question

<UserControl x:Class="blah..my_UserControl "
                 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                 xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                 xmlns:local="clr-namespace:blah."
                 mc:Ignorable="d" 
                 d:DesignHeight="300" d:DesignWidth="300">
    <Grid>
        <GroupBox x:Name="groupBox" Header="Settings" HorizontalAlignment="Center" Margin="0" VerticalAlignment="Top" RenderTransformOrigin="-0.176,-0.343" Width="503" Height="85">
            <Grid>

                <ComboBox x:Name="comboBox" ItemsSource="{Binding PortList}" HorizontalAlignment="Left" Margin="0,30,0,0" VerticalAlignment="Top" Width="120" >
                    <ComboBox.ItemTemplate>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal">
                                <TextBox Text="{Binding}" Width="16" Height="16" Margin="0,2,5,2" />
                            </StackPanel>
                        </DataTemplate>
                    </ComboBox.ItemTemplate>
                </ComboBox>

                </Grid>
            </GroupBox>
        </Grid>
</UserControl>

public partial class Child: Base
{
    public Child()
    {
        PortList.add("com1");
    }
}

public abstract class Base : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    protected void NotifyPropertyChanged(string info)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(info));
    }
    private ObservableCollection<string> portlist;
    public ObservableCollection<string> PortList
    {
        get { return portlist; }
        set
        {
            portlist = value;
            NotifyPropertyChanged("PortList");
        }
    }
    public Base()
    {
        PortList = new ObservableCollection<string>();
    }
}

public partial class my_UserControl : UserControl
{
    public my_UserControl(Base base)
    {
        InitializeComponent();
        DataContext = base;
    }
}

当我创建一个新的子类时，组合框列表中没有任何内容。它似乎与组合框有关，因为我以完全相同的方式绑定其他几个东西并且它们都起作用。

我在MainWindow.xaml.cs中初始化用户控件和子类

Child child = new Child()
my_userControl control = new my_userControl(child)

//然后将控件添加到mainWindow。

当我点击组合框时，它会抛出此异常。

System.Windows.Data Error: 8 : Cannot save value from target back to source. BindingExpression:Path=IsDropDownOpen; DataItem='ComboBox' (Name='comboBox'); target element is 'ToggleButton' (Name=''); target property is 'IsChecked' (type 'Nullable`1') XamlParseException:'System.Windows.Markup.XamlParseException: Two-way binding requires Path or XPath. ---> System.InvalidOperationException: Two-way binding requires Path or XPath.
   at System.Windows.Data.BindingExpression.CreateBindingExpression(DependencyObject d, DependencyProperty dp, Binding binding, BindingExpressionBase parent)

Answer 1

child不应该是使用InitializeComponent()方法的部分视图类。

它应该是一个继承自Base的简单派生类：

public class child : Base
{
    public child()
    {
        PortList.add("com1");
    }
}

然后，您应该将定义了XAML的DataContext的{{1}}设置为UserControl的实例：

child

当我点击组合框时，它会抛出此异常。

将绑定模式更改为OneWay或绑定到类的属性：

public partial class my_UserControl : UserControl
{
    public my_UserControl()
    {
        InitializeComponent();
        DataContext = new child();
    }
}

WPF数据将字符串列表绑定到组合框

1 个答案: