如何取消选择 DataGrid 中的所有项目？

Question

我有一个 WPF-App (.Net Framework 4.7.2.)，里面有一个 DataGrid，其中列出了项目。我通过 MVVM-Concept 构建了应用程序，所以我有一个 MainWindowViewModel，在这一层是我的 DataGrid。然后我有一个ProjectsViewModel，里面有一个叫SelectedProject的Property，这是我当前选中的Project。在 ProjectsViewModel 里面，有 ProjectViewModel，在这个 ViewModel 里面，有所有需要的属性，用数据填充我的 DataGrid。

一切正常，但我确实有一个问题......

如果我想取消选择一个项目，我必须通过单击它来选择另一个项目。如何取消选择所有项目，例如通过单击 DataGrid 的外部，所以我的问题是，有没有可能的方法来取消选择 DataGrid 中的所有项目，是否有可能是一个事件或其他什么？

这是我的 DataGrid XAML 代码：

<DataGrid x:Name="Data" x:Uid="Data" Margin="10,41,10,123" DataContext="{Binding Path=ProjectsViewModel}" ItemsSource="{Binding Path=Projects}" SelectedItem="{Binding Path=SelectedProject}" AutoGenerateColumns="False" IsEnabled="{Binding Path=IsEditable}">
                <DataGrid.RowStyle>
                    <Style TargetType="DataGridRow">
                        <Style.Triggers>
                            <DataTrigger Binding="{Binding Path=IsCheckedIn}" Value="true">
                                <Setter Property="Background" Value="LightGreen"/>
                            </DataTrigger>
                            <DataTrigger Binding="{Binding Path=IsCheckedIn}" Value="false">
                                <Setter Property="Background" Value="Transparent"/>
                            </DataTrigger>
                        </Style.Triggers>
                    </Style>
                </DataGrid.RowStyle>
                <DataGrid.Columns>
                    <DataGridTextColumn x:Name="GridHeadProjectNumber" x:Uid="GridHeadProjectNumber" Header="Projekt" Binding="{Binding Path=IssueKey}" IsReadOnly="True">
                        <DataGridTextColumn.ElementStyle>
                            <Style TargetType="TextBlock">
                                <Setter Property="HorizontalAlignment" Value="Center"/>
                                <Setter Property="Margin" Value="2,0,2,0"/>
                            </Style>
                        </DataGridTextColumn.ElementStyle>
                    </DataGridTextColumn>
                    <DataGridTextColumn x:Name="GridHeadTitle" x:Uid="GridHeadTitle" Header="Titel" Binding="{Binding Path=Summary}" IsReadOnly="True"/>
                    <DataGridTextColumn x:Name="GridHeadStatus" x:Uid="GridHeadStatus" Header="Status" Binding="{Binding Path=Status}" IsReadOnly="True"/>
                    <DataGridTextColumn x:Name="GridHeadTimeSpent" x:Uid="GridHeadTimeSpent" Header="Bisher gearbeitete Zeit" Binding="{Binding Path=TimeSpent}" IsReadOnly="True"/>
                    <DataGridTextColumn x:Name="GridHeadDueDate" x:Uid="GridHeadDueDate" Header="Fälligkeit" Binding="{Binding Path=DueDate, StringFormat={}{0:dd.MM.yyyy HH:mm}}" IsReadOnly="True"/>
                    <DataGridTextColumn x:Name="GridHeadLastCheckIn" x:Uid="GridHeadLastCheckIn" Header="Letzter Checkin" Binding="{Binding Path=LastCheckIn, StringFormat={}{0:dd.MM.yyyy HH:mm}}" IsReadOnly="True"/>
                    <DataGridTemplateColumn x:Name="GridButtonCheckIn" x:Uid="GridButtonCheckIn" Header="CheckIn" >
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <Button Name="btnCheckIn" Uid="btnCheckIn" Content="{Binding Path=CheckInOutText}" Command="{Binding Path=CheckInCommand}" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn x:Name="GridButtonOpenInBrowser" x:Uid="GridButtonOpenInBrowser" Header="Öffnen" >
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <Button Name="btnOpenInBrowser" Uid="btnOpenInBrowser" Content="Öffnen" Command="{Binding Path=OpenInBrowserCommand}" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
            </DataGrid>

这是我在 ProjectsViewModel 中的 SelectedProject 属性：

public ProjectViewModel SelectedProject
        {
            get => _selectedProject;
            set
            {
                _selectedProject = value;
                NotifyPropertyChanged(nameof(SelectedProject));
                CheckInSelectedProjectCommand.NotifyCanExecuteChanged();
                OpenSelectedProjectCommand.NotifyCanExecuteChanged();
                // Minimize()
            }
        }

这是我的 ProjectViewModel 类：

public partial class ProjectViewModel : ViewModelBase
    {
        private readonly IJiraManager _jiraManager;
        private readonly IProjectWorkflow _projectWorkflow;
        private readonly IBroker _broker;
        private Action _checkOutAllProjects;
        private readonly IWindow _window;
        private readonly SettingsViewModel _settingsViewModel;
        private readonly TaskbarViewModel _taskbarViewModel;
        private Project _project;
        private bool _isCheckedIn = false;
        private DateTime? _currentCheckIn;

        public ProjectViewModel(IJiraManager jiraManager, IProjectWorkflow projectWorkflow, Project project, Action checkOutAllProjects, IWindow window, SettingsViewModel settingsViewModel, IBroker broker, TaskbarViewModel taskbarViewModel, IDateTimeProvider dateTimeProvider)
        {
            this.InitializeCommands();
            _jiraManager = jiraManager ?? throw new ArgumentNullException(nameof(jiraManager));
            _project = project ?? throw new ArgumentNullException(nameof(project));
            _checkOutAllProjects = checkOutAllProjects ?? throw new ArgumentNullException(nameof(checkOutAllProjects));
            _window = window ?? throw new ArgumentNullException(nameof(window));
            _settingsViewModel = settingsViewModel ?? throw new ArgumentNullException(nameof(settingsViewModel));
            _broker = broker ?? throw new ArgumentNullException(nameof(broker));
            _taskbarViewModel = taskbarViewModel ?? throw new ArgumentNullException(nameof(taskbarViewModel));
            _projectWorkflow = projectWorkflow ?? throw new ArgumentNullException(nameof(projectWorkflow));
            _dateTimeProvider = dateTimeProvider ?? throw new ArgumentNullException(nameof(dateTimeProvider));
        }
 
        public bool IsCheckedIn
        {
            get => _isCheckedIn;
            set
            {
                _isCheckedIn = value;
                NotifyPropertyChanged(nameof(IsCheckedIn));
                NotifyPropertyChanged(nameof(CheckInOutText));
                if (value)
                {
                    _broker.Publish(this, new ProjectCheckInMessage(this));
                }
                if (_settingsViewModel.MinimizeAfterCheckIn)
                {
                    _window.Minimize();
                }
            }
        }
        public DateTime? CurrentCheckIn { get { return _currentCheckIn; } set { _currentCheckIn = value; } }
        public string Summary { get => _project.Summary; }
        public string Status { get => _project.Status; }
        public string IssueKey { get => _project.IssueKey; }
        public string TimeSpent { get => _project.TimeSpent; }
        public DateTime? DueDate { get => _project.DueDate; }
        public DateTime? LastCheckIn { get => _project.LastCheckIn; }
        public string CheckInOutText { get => IsCheckedIn ? "Check Out" : "Check In"; }
    }

我希望你能帮助我:)

Answer 1

更新：我使用了 LostFocus 事件并将其绑定到名为 IsProjectSelected 的 porperty，如果该事件被触发，我检查是否为 ProjectIsSelected，如果选择了一个项目，我取消选择它。这是我的代码：

事件处理程序：

LostFocus += MainWindowViewModel.ProjectsViewModel.DataGrid_LostFocus;

事件方法：

public void DataGrid_LostFocus(object sender, RoutedEventArgs e)
        {
            if(IsProjectSelected)
            {
                IsProjectSelected = false;
            }
        }

在 SelectedProject 属性的设置器中，我设置了 IsSelectedProject 的值；：

public ProjectViewModel SelectedProject
        {
            get => _selectedProject;
            set
            {
                _selectedProject = value;
                NotifyPropertyChanged(nameof(SelectedProject));
                CheckInSelectedProjectCommand.NotifyCanExecuteChanged();
                OpenSelectedProjectCommand.NotifyCanExecuteChanged();
                IsProjectSelected = true;
                // Minimize()
            }
        }