c# - 在 WPF 中使用 MVVM 从其他绑定(bind)更新绑定(bind)

Question

有人对如何解决我的问题有任何建议吗？我有一个数据网格绑定(bind)到 ModelCheckoutRecord 的集合对象(ListModelCheckoutRecords)。我将所选项目绑定(bind)到 ModelCheckoutRecord (SelectedItemModelCheckoutRecord)。在所选项目的绑定(bind)中，我想更新另一个 datagrid 和 gridsplitter ( ResponseVisibility ) 的可见性绑定(bind)。从其他绑定(bind)更新绑定(bind)的能力似乎不起作用？

我的 XAML 行如下:

            <Grid>
                <Grid.RowDefinitions>
                    <View:RowDefinitionExtended Height="Auto"/>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto"/>
                </Grid.RowDefinitions>
                <DataGrid AutoGenerateColumns="True" ItemsSource="{Binding ListModelCheckoutRecord}" SelectedItem="{Binding SelectedModelCheckoutRecord}" MouseLeftButtonDown="DataGrid_MouseLeftButtonDown" CommandManager.PreviewExecuted="DataGrid_DeletePreviewExecuted" IsReadOnly="False" CanUserAddRows="False" CanUserDeleteRows="True" Margin="15" Grid.Row="0"/>
                <GridSplitter HorizontalAlignment="Stretch" Visibility="{Binding ResponseVisibility}" Grid.Row="1"/>
                <DataGrid AutoGenerateColumns="True" ItemsSource="{Binding ListModelResponseRecord}" SelectedItem="{Binding SelectedModelResponseRecord}" MouseLeftButtonDown="DataGrid_MouseLeftButtonDown" IsReadOnly="False" CanUserAddRows="False" CanUserDeleteRows="False" Visibility="{Binding ResponseVisibility}" Margin="15" Grid.Row="2"/>
            </Grid>

给我带来麻烦的精简代码如下:

    private Visibility responseVisibility = Visibility.Visible;
    public Visibility ResponseVisibility
    {
        get { return responseVisibility; }
        set
        {
            if (value == responseVisibility)
            {
                return;
            }

            responseVisibility = value;
            RaisePropertyChanged("ResponseVisibility");
        }
    }

    private List<ModelCheckoutRecord> listModelCheckoutRecord;
    public List<ModelCheckoutRecord> ListModelCheckoutRecord
    {
        get { return listModelCheckoutRecord; }
        set
        {
            if (value == listModelCheckoutRecord)
            {
                return;
            }

            listModelCheckoutRecord = value;
            RaisePropertyChanged("ListModelCheckoutRecord");

            ResponseVisibility = Visibility.Collapsed;
        }
    }

    private ModelCheckoutRecord selectedModelCheckoutRecord;
    public ModelCheckoutRecord SelectedModelCheckoutRecord
    {
        get { return selectedModelCheckoutRecord; }
        set
        {
            if (value == null)
            {
                ResponseVisibility = Visibility.Collapsed;
                return;
            }

            else
            {
                ResponseVisibility = Visibility.Visible;
            }

            if (selectedModelCheckoutRecord == value)
            {
                return;
            }

            RaisePropertyChanged("SelectedModelCheckoutRecord");
        }
    }

谢谢

理查德

Answer 1

假设您真的希望在 null 的情况下拥有折叠的可见性SelectedItem只是，实际上没有必要为此使用代码。以下 XAML 可以很好地完成这项工作。

只需给您的源 DataGrid 一个名称(我在以下示例中假设 Grid 作为名称)并在目标 DataGrid 中使用如下样式:

<DataGrid x:Name="TargetGridJustToShowWhereThisGoes">
    <DataGrid.Style>
        <Style TargetType="DataGrid">
            <Style.Triggers>
                <DataTrigger Binding="{Binding ElementName=Grid, Path=SelectedItem}" Value="{x:Null}">
                    <Setter Property="Visibility" Value="Collapsed" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </DataGrid.Style>
</DataGrid>