c# - 在数据网格中编辑当前选定的项目

Question

嘿，

我正在使用 MVVM 创建简单的应用程序，偶然发现了一个我发现很难解决的问题。在我的应用程序中，我有数据网格和几个控件来编辑数据网格中当前选定的项目。在我的 ViewModel 中，我有 CurrentSequence 属性，其中包含 ColorSettingsSequencesSequence 对象(这些对象的集合用作数据网格的 DataContext)。

这是 xaml:

<DataGrid AutoGenerateColumns="False" ItemsSource="{Binding Path=ColorSettingsSequences}"
                  SelectedItem="{Binding Path=CurrentSequence, Mode=TwoWay}">
    .... more things here ...
</DataGrid>

<StackPanel Grid.Column="0" Grid.Row="0">
    <Grid>
        <Label Content="Start temperature (°C)" Height="28" HorizontalAlignment="Left" x:Name="lblSeqStartTemp" VerticalAlignment="Top" />
        <TextBox Height="23" Margin="0,28,10,0" x:Name="tbSeqStartTemp" VerticalAlignment="Top" Text="{Binding Path=CurrentSequence.StartTemp}" />
    </Grid>
    <Grid>
        <Label Content="Start color" Height="28" HorizontalAlignment="Left" x:Name="lblSeqHue" VerticalAlignment="Top" />
        <xctk:ColorPicker Margin="0,28,10,0" x:Name="clrpSeqHue" SelectedColor="{Binding Path=CurrentSequence.StartHue, Converter={StaticResource hueToColor}, ConverterParameter=False}" ShowStandardColors="False" />
    </Grid>
</StackPanel>
<StackPanel Grid.Column="1" Grid.Row="0">
    <Grid>
        <Label Content="End temperature (°C)" Height="28" HorizontalAlignment="Left" x:Name="lblSeqEndTemp" VerticalAlignment="Top" />
        <TextBox Height="23" Margin="0,28,10,0" x:Name="tbSeqEndTemp" VerticalAlignment="Top" Text="{Binding Path=CurrentSequence.EndTemp}" />
    </Grid>
    <Grid>
        <Label Content="End color" Height="28" HorizontalAlignment="Left" x:Name="lblSeqEndHue" VerticalAlignment="Top" />
        <xctk:ColorPicker Margin="0,28,10,0" x:Name="clrpSeqEndHue" SelectedColor="{Binding Path=CurrentSequence.EndHue, Converter={StaticResource hueToColor}, ConverterParameter=False}" ShowStandardColors="False" />
    </Grid>
</StackPanel>

代码:

private ColorSettingsSequencesSequence _currentSequence;
public ColorSettingsSequencesSequence CurrentSequence
{
    get
    {
        return this._currentSequence;
    }
    set
    {
        this._currentSequence = value;
        OnPropertyChanged("CurrentSequence");
    }
}

这很好用，但是当我想添加验证时，问题就来了。我想分别验证 StartTemp 和 EndTemp 并给出不同的错误。我将如何分解 ColorSettingsSequencesSequence 对象，以便如果我编辑一个值它也会在数据网格中更新，绑定(bind)也仍然有效？

这是我的尝试，我创建了 2 个新属性并向它们添加了验证:

private String _currentSequenceStartTemp;
public String CurrentSequenceStartTemp
{
    get
    {
        return _currentSequenceStartTemp;
    }
    set
    {
        this._currentSequenceStartTemp = value;
        CurrentSequence.StartTemp = value;
        RaisePropertyChanged("CurrentSequenceStartTemp");
        Validator.Validate(() => CurrentSequenceStartTemp);
        ValidateCommand.Execute(null);
    }
}

private String _currentSequenceEndTemp;
public String CurrentSequenceEndTemp
{
    get
    {
        return _currentSequenceEndTemp;
    }
    set
    {
        this._currentSequenceEndTemp = value;
        CurrentSequence.EndTemp = value;
        RaisePropertyChanged("CurrentSequenceEndTemp");
        Validator.Validate(() => CurrentSequenceEndTemp);
        ValidateCommand.Execute(null);
    }
}

我只是将 TextBoxes 绑定(bind)到这些值，而不是直接将它们绑定(bind)到 CurrentSequence。我还在 setter 中添加了设置 CurrentSequence 值，并希望我的更改将一直推回原始集合并在数据网格中进行更改。那没有发生..当 CurrentSequence 改变时，我也会改变这些属性的值:

private ColorSettingsSequencesSequence _currentSequence;
public ColorSettingsSequencesSequence CurrentSequence
{
    get
    {
        return this._currentSequence;
    }
    set
    {
        this._currentSequence = value;
        RaisePropertyChanged("CurrentSequence");
        if (value != null)
        {
            CurrentSequenceStartTemp = value.StartTemp;
            CurrentSequenceEndTemp = value.EndTemp;
        }
        else
        {
            CurrentSequenceStartTemp = String.Empty;
            CurrentSequenceEndTemp = String.Empty;
        }
    }
}

Answer 1

我已经重现了你的问题。但是我找不到任何问题。一切正常。

• 分别验证 StartTemp 和 EndTemp。
• 如果更新了一个值，则数据网格也应该更新

所以我在项目中解决了以上两个问题。

结果

将起始温度更改为 40 后，datagrid 值也发生了变化。

让我们在开始温度文本框中创建一个错误。

现在是另一个

您现在可以看到这两个属性都分别进行了验证。

这是我创建的项目。

项目结构

ViewModelBase 类

public class ViewModelBase : INotifyPropertyChanged
{
    #region Implementation of INotifyPropertyChanged

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        OnPropertyChanged(new PropertyChangedEventArgs(propertyName));
    }

    protected virtual void OnPropertyChanged(PropertyChangedEventArgs args)
    {
        var handler = PropertyChanged;
        if (handler != null)
            handler(this, args);
    }

    #endregion
}

ColorSettingsSequences序列类

public class ColorSettingsSequencesSequence : ViewModelBase, IDataErrorInfo
{
    #region Declarations

    private string startColor;
    private string startTemperature;
    private string endTemperature;

    #endregion

    #region Properties

    /// <summary>
    /// Gets or sets the start color.
    /// </summary>
    /// <value>
    /// The start color.
    /// </value>
    public string StartColor
    {
        get
        {
            return this.startColor;
        }
        set
        {
            this.startColor = value;
            OnPropertyChanged("StartColor");
        }
    }

    /// <summary>
    /// Gets or sets the start temperature.
    /// </summary>
    /// <value>
    /// The start temperature.
    /// </value>
    public string StartTemperature
    {
        get
        {
            return this.startTemperature;
        }
        set
        {
            this.startTemperature = value;
            OnPropertyChanged("StartTemperature");
        }
    }

    /// <summary>
    /// Gets or sets the end temperature.
    /// </summary>
    /// <value>
    /// The end temperature.
    /// </value>
    public string EndTemperature
    {
        get
        {
            return this.endTemperature;
        }
        set
        {
            this.endTemperature = value;
            OnPropertyChanged("EndTemperature");
        }
    }

    #endregion

    /// <summary>
    /// Gets an error message indicating what is wrong with this object.
    /// </summary>
    /// <returns>An error message indicating what is wrong with this object. The default is an empty string ("").</returns>
    public string Error 
    {
        get 
        {
            return "";
        } 
    }

    /// <summary>
    /// Gets the error message for the property with the given name.
    /// </summary>
    /// <param name="columnName">Name of the column.</param>
    /// <returns></returns>
    public string this[string columnName]
    {
        get 
        {
            if (columnName.Equals("StartTemperature"))
            {
                if (string.IsNullOrEmpty(this.StartTemperature))
                {
                    return "Please enter a start temperature";
                }
            }

            if (columnName.Equals("EndTemperature"))
            {
                if (string.IsNullOrEmpty(this.EndTemperature))
                {
                    return "Please enter a end temperature";
                }
            }

            return "";
        }
    }
}

主视图模型

public class MainViewModel : ViewModelBase
{
    #region Declarations

    private ColorSettingsSequencesSequence currentSequence;
    private ObservableCollection<ColorSettingsSequencesSequence> colorSettingsSequences;

    #endregion

    #region Properties

    /// <summary>
    /// Gets or sets the current sequence.
    /// </summary>
    /// <value>
    /// The current sequence.
    /// </value>
    public ColorSettingsSequencesSequence CurrentSequence
    {
        get
        {
            return this.currentSequence;
        }
        set
        {
            this.currentSequence = value;
            OnPropertyChanged("CurrentSequence");
        }
    }

    /// <summary>
    /// Gets or sets the color settings sequences.
    /// </summary>
    /// <value>
    /// The color settings sequences.
    /// </value>
    public ObservableCollection<ColorSettingsSequencesSequence> ColorSettingsSequences
    {
        get
        {
            return this.colorSettingsSequences;
        }
        set
        {
            this.colorSettingsSequences = value;
            OnPropertyChanged("ColorSettingsSequences");
        }
    }

    #endregion

    #region Commands

    #endregion

    #region Constructors

    /// <summary>
    /// Initializes a new instance of the <see cref="MainViewModel" /> class.
    /// </summary>
    public MainViewModel()
    {
        this.ColorSettingsSequences = new ObservableCollection<ColorSettingsSequencesSequence>();

        ColorSettingsSequencesSequence sequence1 = new ColorSettingsSequencesSequence();
        sequence1.StartColor = "Blue";
        sequence1.StartTemperature = "10";
        sequence1.EndTemperature = "50";
        ColorSettingsSequences.Add(sequence1);

        ColorSettingsSequencesSequence sequence2 = new ColorSettingsSequencesSequence();
        sequence2.StartColor = "Red";
        sequence2.StartTemperature = "20";
        sequence2.EndTemperature = "60";
        ColorSettingsSequences.Add(sequence2);

        ColorSettingsSequencesSequence sequence3 = new ColorSettingsSequencesSequence();
        sequence3.StartColor = "Yellow";
        sequence3.StartTemperature = "30";
        sequence3.EndTemperature = "70";
        ColorSettingsSequences.Add(sequence3);

        this.CurrentSequence = sequence1;

    }

    #endregion

    #region Private Methods

    #endregion
}

主窗口.xaml (XAML)

<Window x:Class="DataGridValidation.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" 
        Height="350"
        Width="525">

    <Window.Resources>
        <Style TargetType="TextBox">
            <Style.Triggers>
                <Trigger Property="Validation.HasError" Value="true">
                    <Setter Property="ToolTip"
                        Value="{Binding RelativeSource={x:Static RelativeSource.Self},
                        Path=(Validation.Errors)[0].ErrorContent}"/>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>

    <Grid Name="mainGrid">

        <Grid.RowDefinitions>
            <RowDefinition Height="149" />
            <RowDefinition Height="73" />
            <RowDefinition Height="123" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="249*" />
        </Grid.ColumnDefinitions>

        <DataGrid AutoGenerateColumns="False" ItemsSource="{Binding ColorSettingsSequences}"
                  SelectedItem="{Binding CurrentSequence}"
                  IsReadOnly="True">

            <DataGrid.Columns>
                <DataGridTextColumn Header="Start Color" Binding="{Binding StartColor}" />
                <DataGridTextColumn Header="End Color" Binding="{Binding StartTemperature}" />
                <DataGridTextColumn Header="End Color" Binding="{Binding EndTemperature}" />
            </DataGrid.Columns>

        </DataGrid>

        <StackPanel Grid.Column="0" Grid.Row="1">
            <Grid>
                <Label Content="Start temperature (°C)" 
                       Height="28" 
                       HorizontalAlignment="Left" 
                       x:Name="lblSeqStartTemp" 
                       VerticalAlignment="Top" />
                <TextBox Height="23" 
                         Margin="10,28,10,0" 
                         x:Name="tbSeqStartTemp" 
                         VerticalAlignment="Top" 
                         Text="{Binding Path=CurrentSequence.StartTemperature, ValidatesOnDataErrors=True, NotifyOnValidationError=True}"/>
            </Grid>
        </StackPanel>
        <StackPanel Grid.Row="2" Margin="0,0,0,43">
            <Grid>
                <Label Content="End temperature (°C)" 
                       HorizontalAlignment="Left"  
                       VerticalAlignment="Top" />
                <TextBox Height="23" 
                         Margin="10,28,10,0" 
                         x:Name="tbSeqEndTemp" 
                         VerticalAlignment="Top" 
                         Text="{Binding Path=CurrentSequence.EndTemperature, ValidatesOnDataErrors=True, NotifyOnValidationError=True}"/>
            </Grid>
        </StackPanel>
    </Grid>
</Window>

MainWindow.xaml.cs(代码隐藏文件)

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        mainGrid.DataContext = new MainViewModel();
    }
}