Datagrid组合框选择项值与文本框的绑定

Question

Hope you are doing well and coding as Guru.

Here comes Datagrid binding problem which is pain for me for 2 days. I asked other other question related to this problem and solved it, but here is other one.

I have RawVal struct and Signal class(has ObservableCollection).

public struct RawVal
{
    public string name { get; set; }
    public int value { get; set; }
}

public class Signal
{
    public string Name { get; set; }
    public Int32 Value { get; set; }
   public ObservableCollection<RawVal> rawValue { get; set; }
}

And now XAML looks like

<DataGrid ItemsSource="{Binding}" Name="grdSignal" Grid.Row="1" CanUserAddRows="False" AutoGenerateColumns="False" SelectionChanged="grdSignal_SelectionChanged_1">
     <DataGrid.Columns>
        <DataGridTextColumn Header="            Signal Name" Binding="{Binding Name}" Width="150"/>
           <DataGridTemplateColumn Header="   Physical Value " Width="100">
              <DataGridTemplateColumn.CellTemplate>
                 <DataTemplate>
                      <ComboBox ItemsSource="{Binding rawValue}" SelectedItem="Binding name"  DisplayMemberPath="name" Name="cmbVal" SelectedIndex="0" 
                             Visibility="{Binding Path=rawValue.Count, Converter={StaticResource ComboBoxItemCountToEnabledConverter}}"/>
                 </DataTemplate>
          </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
            <DataGridTemplateColumn Header="    Value " Width="100">
                <DataGridTemplateColumn.CellTemplate>
                   <DataTemplate>
                       <TextBox Text="{Binding }" />
                   </DataTemplate>
               </DataGridTemplateColumn.CellTemplate>
          </DataGridTemplateColumn>
        </DataGrid.Columns>
     </DataGrid> 

UI with binding

Problem is when user selects any item from Physical Value Combobox, value related to this item needs to be shown in Value textbox.

For example, RawVal in Signal class contains these values.

4 - Search Key Trigger
3 - Tailgate Key Trigger
2 - Un-Lock Key Trigger 
1 - Lock Key Trigger
0 - No Remote RQ Trigger

When user selects "Tailgate Key Trigger", 3 appears in textbox. When "No Remote RQ Trigger" selected, 0.

Any suggestions and solutions are welcomed, Thank you.

Answer 1

I have created a simple solution based on MVVM to just guide you how can it be done.

ViewModel class

class ViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private ObservableCollection<Signal> _source;
    public IEnumerable<Signal> MySource
    {
        get { return _source; }
    }

    private RawVal _rawValSelected;
    public RawVal RawValSelected
    {
        get { return _rawValSelected; }
        set
        {
            _rawValSelected = value;

            RaisePropertyChanged("RawValSelected");
        }
    }

    public void RaisePropertyChanged(string propName)
    {
        var pc = PropertyChanged;
        if (pc != null)
        {
            pc(this, new PropertyChangedEventArgs(propName));
        }
    }

    public ViewModel()
    {
        _source = new ObservableCollection<Signal>
        {
            new Signal{
                Name = "Test",
                Value = 1,
                rawValue = new ObservableCollection<RawVal>
                {
                    new RawVal{name="Search Key Trigger",value=4},
                    new RawVal{name="Tailgate Key Trigger",value=3},
                    new RawVal{name="Un-Lock Key Trigger",value=2},
                    new RawVal{name="Lock Key Trigger",value=1},
                    new RawVal{name="No Remote RQ Trigger",value=0}
                }
            }
        };
    }
}

The view

<DataGrid ItemsSource="{Binding MySource}" Name="grdSignal" CanUserAddRows="False" AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn Header="Signal Name" Binding="{Binding Name}" Width="150" />
        <DataGridTemplateColumn Header="Physical Value " Width="100">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <ComboBox ItemsSource="{Binding rawValue}"
                              SelectedItem="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}},Path=DataContext.RawValSelected}"
                              DisplayMemberPath="name" SelectedIndex="0" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
        <DataGridTemplateColumn Header="Value" Width="100">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBox Text="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}},Path=DataContext.RawValSelected.value}"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

I removed some of your code since I don't have the converter code Note the use of RelativeSource which helps me bind the selected value of the combobox to a property in the view model

The code behind of the view

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

Answer 2

You have to have INotifyPropertyChanged event implemented for Signal , and use SelectedItem property of your Combobox to set the value for TextBox column.

Xaml code :

<DataGrid ItemsSource="{Binding}" Name="grdSignal" Grid.Row="1" CanUserAddRows="False" AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn Header="            Signal Name" Binding="{Binding Name}" Width="150"/>
        <DataGridTemplateColumn Header="   Physical Value " Width="100">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <ComboBox  ItemsSource="{Binding rawValue, Mode=OneWay}" SelectedItem="{Binding SelectedRaValue, Mode=TwoWay,  UpdateSourceTrigger=PropertyChanged}"  DisplayMemberPath="name" Name="cmbVal"
                             Visibility="{Binding Path=rawValue.Count, Converter={StaticResource ComboBoxItemCountToEnabledConverter}}" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
        <DataGridTemplateColumn Header="    Value " Width="100">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBox Text="{Binding ComboValue}"  />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

C# / code behind

public class Signal: INotifyPropertyChanged 
{
    public string Name 
    {
        get;
        set;
    }
    public Int32 Value 
    {
        get;
        set;
    }
    private ObservableCollection < RawVal > rawValue1;
    public ObservableCollection < RawVal > rawValue 
    {
        get 
        {
            return rawValue1;
        }
        set 
        {
            rawValue1 = value;
            OnPropertyChanged("rawValue");
            if (value != null && value.Count > 0) 
            {
                SelectedRaValue = value.First();
            }
        }
    }

    private RawVal selectedRaValue;
    public RawVal SelectedRaValue 
    {
        get 
        {
            return selectedRaValue;
        }
        set 
        {
            selectedRaValue = value;
            OnPropertyChanged("SelectedRaValue");
            ComboValue = value.name;
            OnPropertyChanged("ComboValue");
        }
    }

    public string ComboValue 
    {
        get;
        set;
    }

    #region Implementation of INotifyPropertyChanged

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName) 
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }

    #endregion
}

Now you can set your DataContext

 List < Signal > collection = new List < Signal > ();
 collection.AddRange((new[] 
 {
    new Signal
    {
        Name = "Hello",
        Value = 1,
        rawValue = new ObservableCollection < RawVal > ((new[] {
            new RawVal { name = "A", value = 1}, 
            new RawVal {name = "B", value = 1}
        }).ToList()),
    },
    new Signal {
        Name = "World",
        Value = 2,
        rawValue = new ObservableCollection < RawVal > ((new[] {
            new RawVal {name = "A", value = 1}, 
            new RawVal {name = "B", value = 1}
        }).ToList()),
    }
 }).ToList());

 this.DataContext = collection;

Hope this helps !!