来自c＃WPF应用程序中DataGrid的值，使用复选框

Question

I have a WPF Application and have populated a DataGrid with values from a SQL query. I have added a DataGridCheckBoxColumn and button to the window. When the button is clicked I want to grab the data from the first selected row and insert into a text box or store as a variable. Please explain the answer in a way that someone who is new to c# developing would understand so I can learn rather than copy and paste.

Here is my XAML:

  <Window x:Class="WpfApplication7.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="NAME SELECT" 
    SizeToContent="WidthAndHeight"
    >
<Grid >
    <Grid.ColumnDefinitions>
        <ColumnDefinition/>
    </Grid.ColumnDefinitions>
    <DataGrid x:Name="selectDataGrid" HorizontalAlignment="Left" VerticalAlignment="Top" Height="92" Width="288" AutoGenerateColumns="False">
        <Style  TargetType="{x:Type DataGridRow}" >

        </Style>
        <DataGrid.Columns>
            <DataGridCheckBoxColumn x:Name="dgCheckBox" Header="Select" Width="45" Binding="{Binding IsChecked}"/>
            <DataGridTextColumn Header="FIRST NAME" Width="125" Binding="{Binding FNAME}"/>
            <DataGridTextColumn Header="LAST NAME" Width="125" Binding="{Binding LNAME}"/>
        </DataGrid.Columns>


    </DataGrid>
    <Button Content="Update Fields" HorizontalAlignment="Left" Margin="193,97,0,0" VerticalAlignment="Top" Width="95" Click="Button_Click"/>

</Grid>

Here is my c# behind:

          private void Button_Click(object sender, RoutedEventArgs e)
    {
        for (int i = 0; i < selectDataGrid.Items.Count -1; i++) 
        {
            DataGridRow cell = GetRow(i);
            CheckBox tb = cell.value as CheckBox;
            System.Windows.MessageBox.Show(tb.IsChecked.ToString());
        }

    }
          public DataGridRow GetRow(int index)
    {
        DataGridRow row = (DataGridRow)selectDataGrid.ItemContainerGenerator.ContainerFromIndex(index);
        if (row == null)
        {
            selectDataGrid.UpdateLayout();
            selectDataGrid.ScrollIntoView(selectDataGrid.Items[index]);
            row = (DataGridRow)selectDataGrid.ItemContainerGenerator.ContainerFromIndex(index);
        }
        return row;
    }

If I could get help to the point of displaying the selected result to a message box I could go from there. I'm only interested in the FIRST instance of a selected row. So if multiple rows are selected I'm only interested in the first row selected.

I have read all the solutions to anything that had my keywords and I cannot find anything that fits my specific need of only wanting the first row. I'm not experienced enough to be able to make leaps and jumps or to alter code for something else to work for me. If you are going to link me to another solution please explain what I would need to change on my code, or what parts I would need from the solution. Ideally working code in a solution is what would be best.

Answer 1

I can suggest you the next solution; data grid has readonly dependency property (link to dependency property: msdn explanation and WPF Dependency Property , CodeProject explanation ) which cannot be accessed from XAML but you can access this in code behind or behavior code (link to behavior: good behavior explanation and anothere one good explanation ). If you access this property and get the first member in that collection you will have the first selected item in your hands. But I frankly advice you to learn the MVVM (link to MVVM: CodeProject explanation and more ) pattern. The MVVM pattern is the a correct way to work with the WPF. Solution: 1. XAML code:

<Window x:Class="SimpleDataGrid.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:simpleDataGrid="clr-namespace:SimpleDataGrid"
    Title="MainWindow" Height="350" Width="525">
<Grid >
    <Grid.RowDefinitions>
        <RowDefinition Height="*"></RowDefinition>
        <RowDefinition Height="Auto"></RowDefinition>
    </Grid.RowDefinitions>
    <Grid.DataContext>
        <simpleDataGrid:GridViewModel/>
    </Grid.DataContext>
    <DataGrid x:Name="SelectDataGrid" ItemsSource="{Binding Persons}" HorizontalAlignment="Left" VerticalAlignment="Top" AutoGenerateColumns="False">
       <DataGrid.Resources>
            <Style  TargetType="{x:Type DataGridRow}" >

            </Style>
        </DataGrid.Resources>
        <DataGrid.Columns>
            <DataGridCheckBoxColumn x:Name="dgCheckBox" Header="Select" Width="45" Binding="{Binding IsChecked}"/>
            <DataGridTextColumn Header="FIRST NAME" Width="125" Binding="{Binding FNAME}"/>
            <DataGridTextColumn Header="LAST NAME" Width="125" Binding="{Binding LNAME}"/>
        </DataGrid.Columns>
    </DataGrid>
    <Button Grid.Row="1" Content="Update Fields" HorizontalAlignment="Left" Margin="5" VerticalAlignment="Top" Width="95" Click="Button_Click"/>

</Grid></Window>

2. View Model code:

    public class GridViewModel:BaseObservableObject
{
    public GridViewModel()
    {
        var l = new List<Person>
        {
            new Person {FNAME = "John", LNAME = "W"},
            new Person {FNAME = "George", LNAME = "R"},
            new Person {FNAME = "Jimmy", LNAME = "B"},
            new Person {FNAME = "Marry", LNAME = "B"},
            new Person {FNAME = "Ayalot", LNAME = "A"},
        };
        Persons = new ObservableCollection<Person>(l);
    }

    public ObservableCollection<Person> Persons { get; set; }
}

3. Code behind and Person model:

    public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        var dataGrid = SelectDataGrid;
        var selected = dataGrid.SelectedItems.Cast<Person>().ToList();
        var mostFirst = selected.FirstOrDefault();
    }
}


public class Person : BaseObservableObject
{
    private string _lName;
    private string _fName;
    private bool _checked;

    public bool IsChecked
    {
        get { return _checked; }
        set
        {
            _checked = value;
            OnPropertyChanged();
        }
    }

    public string LNAME
    {
        get { return _lName; }
        set
        {
            _lName = value;
            OnPropertyChanged();
        }
    }

    public string FNAME
    {
        get { return _fName; }
        set
        {
            _fName = value;
            OnPropertyChanged();
        }
    }
}

4. BaseObservableObject code (simple implementation of INotifyPropertyChanged):

  public class BaseObservableObject : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

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

    protected virtual void OnPropertyChanged<T>(Expression<Func<T>> raiser)
    {
        var propName = ((MemberExpression)raiser.Body).Member.Name;
        OnPropertyChanged(propName);
    }

    protected bool Set<T>(ref T field, T value, [CallerMemberName] string name = null)
    {
        if (!EqualityComparer<T>.Default.Equals(field, value))
        {
            field = value;
            OnPropertyChanged(name);
            return true;
        }
        return false;
    }
}

I hope it will help you. Regards.