Question

我有一个带有ObservableCollection的ViewModel，以及一个使用Xaml声明的CollectionViewSource的视图，该视图绑定到DataGrid.ItemsSource。

ViewModel有一个命令来创建一个新对象并将其添加到ObservableCollection。同样在ViewModel中，我正在处理CollectionChanged事件，因此我“知道”何时发生添加。

我怀疑是：

如何在DataGrid中选择刚刚添加的对象？

请注意，添加和更改的事件都在ViewModel中，但选择必须在视图中进行。

我不介意基于代码隐藏的解决方案。

视图模型：

public class TelaInicialViewModel : ViewModelBase
{
    public ObservableCollection<PacienteViewModel> Pacientes { get; set; }

    IRepositório<Paciente> _repositório_pacientes = new RepositórioPaciente();

    // CONSTRUTOR
    public TelaInicialViewModel()
    {
        var pacientes = _repositório_pacientes.Items.Select(p => new PacienteViewModel(p));
        Pacientes = new ObservableCollection<PacienteViewModel>(pacientes);
        Pacientes.CollectionChanged += Pacientes_CollectionChanged;
    }


    void Pacientes_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        switch (e.Action)
        {
            case NotifyCollectionChangedAction.Add:
                foreach (var added in e.NewItems)
                {
                    var p = added as PacienteViewModel;
                    if (p != null)
                    {
                        var novoPaciente = p.GetModel();  /////////  HERE I HAVE IT!!
                        _repositório_pacientes.Adicionar(novoPaciente);
                    }
                }
                break;
            case NotifyCollectionChangedAction.Replace:
                // ...
                break;
        }
    }


    void AdicionarPaciente()
    {
        var formulárioPaciente = new FormulárioCriaçãoPaciente();
        PacienteViewModel novoPaciente = formulárioPaciente.ExibirDiálogo(new Paciente());
        if (novoPaciente != null)
            //////// HERE I HAVE IT!!!
            Pacientes.Add(novoPaciente);
    }
    public ICommand ComandoAdicionarPaciente { get { return new RelayCommand(AdicionarPaciente); } }
}

查看（Xaml）

<UserControl.Resources>

    <CollectionViewSource
        x:Key="PacientesViewSource"
        Source="{Binding Pacientes}"
        Filter="PacientesViewSource_Filter"/>

</UserControl.Resources>


<DockPanel>

    <DockPanel DockPanel.Dock="Top" Margin="0,10,0,0" >
        <TextBox x:Name="FiltroPacienteTextBox" Height="30"
            TextChanged="FiltroPacienteTextBox_TextChanged"
            DockPanel.Dock="Bottom" Margin="10,10,10,0"/>
        <Button x:Name="botaoNovoPaciente" Width="120" Content="Novo"
            HorizontalAlignment="Left" Height="30" Margin="10,0,0,0"
            Command="{Binding ComandoAdicionarPaciente}"/>
    </DockPanel>

    <DataGrid x:Name="pacienteDataGrid" Margin="0,10,0,0"
        AutoGenerateColumns="False"
        CanUserAddRows="False" CanUserDeleteRows="False"
        CanUserReorderColumns="False" CanUserResizeRows="False"
        ItemsSource="{Binding Source={StaticResource PacientesViewSource}}"
        IsSynchronizedWithCurrentItem="True">
    </DataGrid>

</DockPanel>

Answer 1

我建议你坚持使用MVVM模式。在这种情况下，我通常会向ViewModel添加表示所选项的属性。这使得ViewModel中的所有重要逻辑都可以在其中进行测试。我会在您的ViewModel中添加以下内容（如果您的ViewModel是DependencyObject，您可以在此使用DependencyProperty：

private Paciente _SelectedPaciente;
public Paciente SelectedPaciente
{
    get { return this._SelectedPaciente; }
    set
    {
        if (this._SelectedPaciente != value)
        {
            this._SelectedPaciente = value;
            this.RaisePropertyChanged("SelectedPaciente");
        }
    }
}

然后像这样修改你的DataGrid：

<DataGrid x:Name="pacienteDataGrid" 
          Margin="0,10,0,0"
          AutoGenerateColumns="False"
          CanUserAddRows="False"
          CanUserDeleteRows="False"
          CanUserReorderColumns="False"
          CanUserResizeRows="False"
          ItemsSource="{Binding Source={StaticResource PacientesViewSource}}"
          SelectedItem="{Binding SelectedPaciente, Mode=TwoWay}"
          IsSynchronizedWithCurrentItem="True">

然后像这样修改AdicionarPaciente：

void AdicionarPaciente()
{
    var formulárioPaciente = new FormulárioCriaçãoPaciente();
    PacienteViewModel novoPaciente = formulárioPaciente.ExibirDiálogo(new Paciente());
    if (novoPaciente != null)
    {
        //////// HERE I HAVE IT!!!
        Pacientes.Add(novoPaciente);
        this.SelectedPaciente = novoPaciente;
    }
}

现在，您可以为ViewModel编写单元测试，以确认在调用添加新Paciente的命令时，选择了新的Paciente。

Answer 2

那么，看看评论中提出的一些答案，我发现了一种非常方便的方法来做我想要的事情：

查看（代码隐藏）

public partial class TelaInicialView : UserControl
{
    CollectionViewSource _pacientes_source;

    public TelaInicialView()
    {
        InitializeComponent();

        Loaded += TelaInicialView_Loaded;
    }


    void TelaInicialView_Loaded(object sender, RoutedEventArgs e)
    {
        _pacientes_source = FindResource("PacientesViewSource") as CollectionViewSource;

        // FIRST STEP: CAST CollectionView.Source to INotifyCollectionChanged, and listen to its CollectionChanged event
        var source = _pacientes_source.Source as INotifyCollectionChanged;
        source.CollectionChanged += TelaInicialView_CollectionChanged;
    }

    void TelaInicialView_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        // SECOND STEP: WHEN YOU ADD SOMETHING, SELECT IT!
        if (e.Action == NotifyCollectionChangedAction.Add)
            pacienteDataGrid.SelectedItem = e.NewItems[0];
    }

    // ...
}

将项添加到ObservableCollection并在其绑定的ListCollectionView中进行选择

视图模型：

查看（Xaml）

2 个答案:

查看（代码隐藏）