我正在使用WPF组合框来过滤项目,但我决定将其放入我的数据网格中,但是我可能无法使其工作,因为只有在数据网格之外时,我才能使其工作.

我认为问题是因为

RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}, or ElementName=win

在datagrid中不受支持,因此如何使它工作.

这是我得到的错误

System.Windows.Data Error: 4 : Cannot find source for binding with reference ‘RelativeSource FindAncestor, AncestorType=’System.Windows.Window’, AncestorLevel=’1”. BindingExpression:Path=SelectedParam; DataItem=null; target element is ‘ComboBox’ (Name=’Krydsmålbox’); target property is ‘SelectedValue’ (type ‘Object’)

<DataGrid x:Name="hjuldata" 
ItemsSource="{Binding Source={StaticResource cvsTasks}}"
CanUserAddRows="False"  BorderBrush="#FF303030" Foreground="#FF00FB0B" Background="#FF303030" AutoGenerateColumns="False" GridLinesVisibility="None" VerticalAlignment="Center" Height="644" Canvas.Left="20" Canvas.Top="257" Width="1250" >
 <DataGrid.Columns>
 <DataGridTextColumn Binding="{Binding Krydsmålet}">
 <DataGridTextColumn.HeaderTemplate>
     <DataTemplate>
        <ContentPresenter Content="{Binding Content, RelativeSource={RelativeSource Mode=TemplatedParent}}"/>
     </DataTemplate>
 </DataGridTextColumn.HeaderTemplate>
  <DataGridTextColumn.Header>
      <ComboBox   x:Name="Krydsmålbox" Foreground="#FFEAEAEA" Background="#FF303030" FontSize="12" 
                  Style="{StaticResource ComboBoxTest2}"  ItemTemplate="{StaticResource cmbTemplate2}" 
                  ItemsSource="{Binding}"  SelectedValuePath="Krydsmålene"
                  SelectedValue = "{Binding SelectedParam, RelativeSource={RelativeSource FindAncestor, 
                  AncestorType={x:Type Window}},UpdateSourceTrigger=PropertyChanged}" BorderBrush="#FF303030" Height="40" DockPanel.Dock="Top" IsSynchronizedWithCurrentItem="True" SelectionChanged="Krydsmålbox_SelectionChanged" Canvas.Left="813" Canvas.Top="96" Width="146"/>
 </DataGridTextColumn.Header>
 </DataGridTextColumn>

数据模板

<DataTemplate x:Key="cmbTemplate2">
    <WrapPanel Margin="0 5 0 5" Height="30">
        <Image Width="10" Height="20" Stretch="Fill" VerticalAlignment="Center" HorizontalAlignment="Center" Margin="0,0,15,0"/>
        <Label Content="{Binding Krydsmålene}" VerticalAlignment="Center" HorizontalAlignment="Center" FontSize="16" Foreground="#FF00FB0B"/>
    </WrapPanel>
</DataTemplate>

CS

public event PropertyChangedEventHandler PropertyChanged;

[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

public string SelectedParam
{
    get { return _selectedParam; }
    set
    {
        _selectedParam = value; OnPropertyChanged("SelectedParam");
        if (_selectedParam == "Krydsmål") { BindData(); } else { hjuldata.ItemsSource = FilterKategori().Tables[0].DefaultView; ; }
    }
}

public DataSet DTbindkryds()
{
    Data = @"SELECT Krydsmålene FROM Data.Krydsmål";
    //SQL statement to fetch entries from Krydsmål
    DataSet dsdata = new DataSet();

    //Open SQL Connection
    using (conn = new SqlConnection(connStrings))
    {
        conn.Open();

        //Initialize command object
        using (conn = new SqlConnection(connStrings))
        using (cmd = new SqlCommand(Data, conn))
        {
            SqlDataAdapter adapters = new SqlDataAdapter(cmd);

            //Fill the result set
            adapters.Fill(dsdata);
            conn.Close();
        }
    }
    return dsdata;
}

private void bindkrydsmål()
{
    Krydsmålbox.ItemsSource = DTbindkryds().Tables[0].DefaultView;
}

解决方法:

我认为您的真正问题很小,而且WPF开发人员经常遇到.更改您的SelectedValue绑定,如下所示：

    SelectedValue = "{Binding DataContext.SelectedParam, RelativeSource={RelativeSource FindAncestor, 
                       AncestorType={x:Type Window}},UpdateSourceTrigger=PropertyChanged}"

由于您没有提供代码,因此无法为窗口分配DataContext,因此这是一个可行的选择.如果是相同的窗口类,则绑定应在没有DataContext的情况下进行.但是数据网格内部不支持RelativeSource绑定的假设是错误的.只要元素在控件的VisualTree中并且您的组合框在窗口的Visualtree中,RelativeSource都将起作用.对？

为了节省时间来证明这一事实,下面是演示(通过最大程度地重复使用代码并使用DataGrid标头中的模板创建).

XAML：

<DataGrid ItemsSource="{Binding Items}" CanUserAddRows="False" AutoGenerateColumns="False" VerticalAlignment="Stretch" >
    <DataGrid.Columns>
        <DataGridTextColumn Binding="{Binding DeviceState}">                
            <DataGridTextColumn.Header>
                <ComboBox HorizontalAlignment="Stretch" Width="200" SelectedValuePath="DeviceState"
                                ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=Window},Path=DataContext.Items}"
                                SelectedValue = "{Binding SelectedParam, RelativeSource={RelativeSource FindAncestor, 
                                AncestorType={x:Type Window}}}" >
                    <ComboBox.ItemTemplate>
                        <DataTemplate>
                            <Label Content="{Binding DeviceState}" VerticalAlignment="Center" HorizontalAlignment="Stretch"/>
                        </DataTemplate>
                    </ComboBox.ItemTemplate>
                </ComboBox>                                    
            </DataGridTextColumn.Header>
        </DataGridTextColumn>
        <DataGridTextColumn Binding="{Binding Name}" Header="Name" Width="200"/>
    </DataGrid.Columns>
</DataGrid>

背后的代码：

 public MainWindow()
    {
        Items = new List<Device>();
        Items.Add(new Device() { Name = "Device1",DeviceState = 1 });
        Items.Add(new Device() { Name = "Device2", DeviceState = 2 });
        Items.Add(new Device() { Name = "Device3", DeviceState = 3 });
        Items.Add(new Device() { Name = "Device4", DeviceState = 4 });
        Items.Add(new Device() { Name = "Device5", DeviceState = 5 });
        InitializeComponent();

    }

    public List<Device> Items { get; set; }

    private string _selectedParam = "1";
    public string SelectedParam
    {
        get { return _selectedParam; }
        set
        {
            _selectedParam = value; 
            UpdateProperty("SelectedParam");                
        }
    }

输出：

正如您在输出中看到的那样,默认情况下,datagrid头中的组合框具有一个选中项,如上XAML所示,这是使用相对源绑定反映出来的.