如何将值从DataGrid：Cell绑定到DataTrigger

Question

My Problem:

• I have a Xceed DataGrid column with a button, which is bound to a Command (that part works)
• Now I want the button to be enabled/disabled depending on a certain value in the current DataRow .
• So far I can either get the command bind work or the DataTrigger depending on the DataContext I use, but not both at the same time.

I am stuck with the following code:

<xcdg:Column FieldName="OpenInPiWebIdentifier"
             Title="PiWeb Report"
             VisiblePosition="6">
    <xcdg:Column.CellContentTemplate>
        <DataTemplate>
            <Button DataContext="{Binding RelativeSource={RelativeSource Self}, Path=(xcdg:DataGridControl.ParentDataGridControl).DataContext}"
                    Content="Open PiWeb"
                    Command="{Binding OpenPiWebCommand}"
                    CommandParameter="{Binding DataContext.ResultData/PiWebReport, Mode=OneWay, RelativeSource={RelativeSource Self}}">
                <Button.Style>
                    <Style TargetType="Button">
                        <Style.Triggers>
                            <DataTrigger Binding="{Binding PiWebReport}"
                                         Value="{x:Null}">
                                <Setter Property="IsEnabled"
                                        Value="False" />
                            </DataTrigger>
                        </Style.Triggers>
                    </Style>
                </Button.Style>
            </Button>
        </DataTemplate>
    </xcdg:Column.CellContentTemplate>
</xcdg:Column>

And the view model implementation of the command:

public ICommand OpenPiWebCommand
{
    get
    {
        return _OpenPiWebCommand;
    }

    set
    {
        if (value != _OpenPiWebCommand)
        {
            _OpenPiWebCommand = value;
            OnPropertyChanged("OpenPiWebCommand");
        }
    }
}

private ICommand _OpenPiWebCommand;

In the constructor I initialize the command:

OpenPiWebCommand = new RelayCommand(new Action<object>(OpenPiWeb));

The property PiWebReport belongs to a class ResultDataV1 . All data is put into this property ResultData = new ObservableCollection<ResultDataV1>(); which is displayed in the DataGrid as columns/rows. So, now I can access either the property value PiWebReport or the command, depending on the context I use, but not both at the same time.

The data class:

public class ResultDataV1
{
    public ResultDataV1(long dataId, DateTime dateTime, DateTime? endDateTime, string partId, string scanId, bool measurementNotVolumejoin, string piWebReport, FileInfo volumeFileInfo, FileInfo volumeVglFileInfo, DirectoryInfo volumeDirectoryInfo, string inspectionPlanName, string paletteName, AutomationStateEnum? automationState);

    public AutomationStateEnum? AutomationState { get; }
    public long DataId { get; }
    public DateTime DateTime { get; }
    public DateTime? EndDateTime { get; }
    public string InspectionPlanName { get; }
    public bool MeasurementNotVolumejoin { get; }
    public string PaletteName { get; }
    public string PartId { get; }
    public string PiWebReport { get; }
    public string ScanId { get; }
    public List<SubResultDataV1> SubResults { get; }
    public DirectoryInfo VolumeDirectoryInfo { get; }
    public FileInfo VolumeFileInfo { get; }
    public FileInfo VolumeVglFileInfo { get; }
}

Answer 1

The main idea is to use the ICommand.CanExecute Method . Initially the button becomes enabled or disabled based on the value of the method (of the bound ICommand instance). Also, firing ICommand.CanExecuteChanged Event can be used to notify the user-interface ( Button class) about the property change.

The implementation of the structure:

internal sealed class ResultData
{
    private readonly string piWebReport;

    public ResultData(string piWebReport)
    {
        this.piWebReport = piWebReport;
    }

    public string PiWebReport
    {
        get { return this.piWebReport; }
    }
}

The implementation of the ViewModel class:

internal sealed class MainViewModel
{
    private readonly IEnumerable<ResultData> items = new[]
        {
            new ResultData("Report 00"),
            new ResultData("Report 01"),
            new ResultData("Report 02"),
            new ResultData(null)
        };

    private readonly ICommand openPiWebCommand;

    public MainViewModel()
    {
        openPiWebCommand = new RelayCommand<ResultData>(
            OpenPiWeb,
            x => x != null && x.PiWebReport != null);
    }

    public IEnumerable<ResultData> Items
    {
        get { return items; }
    }

    public ICommand OpenPiWebCommand
    {
        get { return openPiWebCommand; }
    }

    private void OpenPiWeb(ResultData data)
    {
        // Implement the command logic.
    }
}

XAML:

<Window x:Class="..."
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid"
        ...>
    <Grid>
        <xcdg:DataGridControl ItemsSource="{Binding Items}">
            <xcdg:DataGridControl.Columns>
                <xcdg:Column FieldName="PiWebReport"
                             Title="PiWeb Report">
                    <xcdg:Column.DisplayMemberBindingInfo>
                        <xcdg:DataGridBindingInfo Path="." ReadOnly="True" />
                    </xcdg:Column.DisplayMemberBindingInfo>

                    <xcdg:Column.CellContentTemplate>
                        <DataTemplate>
                            <Grid>
                                <Button Content="Open PiWeb"
                                        CommandParameter="{Binding}"
                                        Command="{Binding RelativeSource={RelativeSource Self}, Path=(xcdg:DataGridControl.ParentDataGridControl).DataContext.OpenPiWebCommand}" />
                            </Grid>
                        </DataTemplate>
                    </xcdg:Column.CellContentTemplate>
                </xcdg:Column>
            </xcdg:DataGridControl.Columns>
        </xcdg:DataGridControl>
    </Grid>
</Window>

References:

• Example of Column.DisplayMemberBindingInfo usage: Difficult choice of grid for projects on WPF .

Hope this is useful for you!