c# - Add context menu in datagrid, how to get the select Item value

Question

I am new in WPF programming with MVVM pattern. Now I have added the context menu in the datagrid. But, when I click the right mouse button, I don't know how to get the select row value. this is my xmal

 <DataGrid  AutoGenerateColumns="False" Grid.Row="1" CanUserAddRows="False" CanUserDeleteRows="False"
              ItemsSource="{Binding StoryList}">
        <DataGrid.Columns>
        <DataGridTextColumn Header="ID" Binding="{Binding ID}" Width="40" IsReadOnly="True" />
        <DataGridTextColumn Header="Title" Binding="{Binding Title}" Width="60" IsReadOnly="True"/>
        <DataGridTextColumn Header="StoryPoints" Binding="{Binding StoryPoints}" Width="90" IsReadOnly="True">
                <DataGridTextColumn.CellStyle>
                    <Style TargetType="DataGridCell">
                        <Style.Triggers>
                            <DataTrigger Binding="{Binding StoryPoints}" Value="0">
                                <Setter Property="Background" Value="Red"/>
                                <Setter Property="ToolTip" Value="Story Point cannot be 0."/>
                            </DataTrigger>                                
                        </Style.Triggers>
                    </Style>
                </DataGridTextColumn.CellStyle>
            </DataGridTextColumn>
            <DataGridTextColumn Header="Stack Rank" Binding="{Binding StackRank}" Width="80"/>
            <DataGridTextColumn Header="Estimate" Binding="{Binding Estimate}" Width="60"/>
            <DataGridTextColumn Header="CompletedWork" Binding="{Binding CompletedWork}" Width="120" />
            <DataGridTextColumn Header="RemainWork" Binding="{Binding RemainWork}" Width="110" />
            <DataGridTextColumn Header="CompleteProcess" Binding="{Binding CompletedProcess}" Width="110" />
            <DataGridTextColumn Header="YesterdayComments" Binding="{Binding YesterdayComments}" Width="120" />
            <DataGridTextColumn Header="TodayComments" Binding="{Binding TodayComments}" Width="120" />
        </DataGrid.Columns>
        <DataGrid.ContextMenu>
            <ContextMenu Name="StoryMenu" StaysOpen="True">
                <MenuItem Header="Add an Issue" Command="{Binding AddIssueCommand}" />
                <MenuItem Header="Burn Down Chart" Command="{Binding BurnDownChartCommand}"/>
            </ContextMenu>
        </DataGrid.ContextMenu>
    </DataGrid>

And here is my viewModel

 class MainViewModel:NotificationObject
{
    private ObservableCollection<Story> storyList;

    public ObservableCollection<Story> StoryList
    {
        get { return storyList; }
        set
        {
            storyList = value;
            this.RaisePropertyChanged("StoryList");
        }
    }
    public DelegateCommand AddIssueCommand { get; set; }
    public DelegateCommand BurnDownChartCommand { get; set; }
    private Story selectStory;

    public Story SelectStory
    {
        get { return selectStory; }
        set
        {
            selectStory = value;
            this.RaisePropertyChanged("SelectStory");
        }
    }

    public void LoadStory()
    {
        this.storyList = new ObservableCollection<Story>();
        Story story1 = new Story(){ID=1, Title="win App", StoryPoints=0, StackRank=1, Estimate=40, CompletedWork=10, RemainWork=30, CompletedProcess=25, TodayComments="Coding", YesterdayComments="N/a"};
        Story story2 = new Story() { ID = 2, Title = "win App", StoryPoints = 10, Estimate = 40, CompletedWork = 10, RemainWork = 30, CompletedProcess = 25, TodayComments = "Coding 20%", YesterdayComments = "N/a" };
        Story story3 = new Story() { ID = 3, Title = "win App", StoryPoints = 10, Estimate = 50, CompletedWork = 20, RemainWork = 30, CompletedProcess = 20, TodayComments = "Coding  30%", YesterdayComments = "N/a" };
        Story story4 = new Story() { ID = 4, Title = "win App", StoryPoints = 10, Estimate = 60, CompletedWork = 30, RemainWork = 30, CompletedProcess = 50, TodayComments = "Coding  40%", YesterdayComments = "N/a" };
        Story story5 = new Story() { ID = 5, Title = "win App", StoryPoints = 10, Estimate = 40, CompletedWork = 10, RemainWork = 30, CompletedProcess = 25, TodayComments = "Coding  50%", YesterdayComments = "N/a" };
        Story story6 = new Story() { ID = 6, Title = "win App", StoryPoints = 10, Estimate = 30, CompletedWork = 30, RemainWork = 0, CompletedProcess = 100, TodayComments = "Coding  60%", YesterdayComments = "N/a" };

        storyList.Add(story1);
        storyList.Add(story3);
        storyList.Add(story2);
        storyList.Add(story4);
        storyList.Add(story5);
        storyList.Add(story6);
    }
    public MainViewModel()
    {
        this.SelectStory = new Story();
        this.LoadStory();
        this.AddIssueCommand = new DelegateCommand(new Action(this.AddIssueCommandExecute));
    }

    public void AddIssueCommandExecute()
    {

        if (SelectStory != null)
        {
            System.Windows.MessageBox.Show("Add an Issue" + SelectStory.Title + "!");
        }
        else
        {
            System.Windows.MessageBox.Show("choose an story first!");
        }
        //System.Windows.MessageBox.Show("record" + RecordIndex);
    }
}![What I need][1]

Thank you very much

Answer 1

Expanding on Bolu's comment you could use SelectedItem to get the current item. Below is a quick example:

<DataGrid ItemsSource="{Binding Source}" SelectedItem="{Binding SelectedItemProperty, Mode=TwoWay}">
    <DataGrid.ContextMenu>
        <ContextMenu>
            <MenuItem Command="{Binding MyCommand}" Header="MyCommand"/>
        </ContextMenu>
    </DataGrid.ContextMenu>
    <DataGrid.Columns>
        <DataGridTextColumn Header="Name" Binding="{Binding Key, Mode=TwoWay}" Width="1*"/>
        <DataGridTextColumn Header="Value" Binding="{Binding Value, Mode=TwoWay}" Width="3*"/>
    </DataGrid.Columns>
</DataGrid>

SelectedItem is now bound to SelectedItemProperty in the ViewModel.