Question

I am developing a User Interface for a host monitoring application, which is already being monitored on database level. I have displayed 2 datagrids on my UI which will populate on run time.These two datagrids are connected by the HostID ( HostID is the Foreign Key in the LogDatagrid).

The First datagrid displays the list of Host with their Status(either Running or Stopped).
I would like to display the Log Status of the respective HostID when a user wants to know the status in detail. How to achieve this when a user selects the Host ID in the HostDatagrid ? I have added my XAML and screenshot of my UI.

XAML

 <DataGrid DataContext="{Binding Path=HostData,NotifyOnTargetUpdated=True,Mode=OneWay}" 
    AutoGenerateColumns="False" Name="hostDatagrid" Margin="171,32,235,230">
    <DataGrid.Columns>
    <DataGridTextColumn Header="Host" Width="auto" Binding="{Binding HostID}" />
     <DataGridTextColumn Header="Status" Width="auto" Binding="{Binding HostStatus}"/> 
     </DataGrid.Columns>
  </DataGrid>
 <DataGrid DataContext="{Binding Path=LogData,NotifyOnTargetUpdated=True,Mode=OneWay}"
   AutoGenerateColumns="False" Name="LogDatagrid" Margin="103,108,102,145">
    <DataGrid.Columns>
    <DataGridTextColumn Header="Host ID" Width="auto"  Binding="{Binding HostID}" />
    <DataGridTextColumn Header="Logs" Width="auto"  Binding="{Binding LogID}" />
    <DataGridTextColumn Header="Log Path" Width="auto"  Binding="{Binding LogPath}"/>
    <DataGridTextColumn Header="Date" Width="auto"  Binding="{Binding Date}"/>
    <DataGridTextColumn Header="Last Activity" Width="auto"  Binding="{Binding LastActivity}"/>
  </DataGrid.Columns>

code behind for the LogFile Model:

    public LogFileModel()
    {

    }
    private int _hostID;
    public int HostID
    {
        get { return _hostID; }
        set { _hostID= value; OnpropertyChanged("HostID"); }
    }

    private string _logid;
    public string LogID
    {
        get { return _logid; }
        set { _logid= value; OnpropertyChanged("LogID"); }
    }

    private string _logpath;
    public string LogPath
    {
        get { return _logPath; }
        set { _logPath = value; OnpropertyChanged("LogPath"); }
    }

    private DateTime _date;
    public DateTime Date;
    {
        get { return _date; }
        set { _date= value; OnpropertyChanged("Date"); }
    }

    private bool _activity;
    public bool LastActivity
    {
        get { return _activity; }
        set { _activity= value; OnpropertyChanged("LastActivity"); }
    }

Code behind for the LogFile ViewModel :

    LogModel _myModel = new LogModel();
    private ObservableCollection<LogFileModel> _logFileData = new  ObservableCollection<LogFileModel>();
    public ObservableCollection<LogFileModel> LogFileData
    {
        get { return _logFileData; }
        set { _logFileData = value; OnPropertyChanged("LogFileData"); }
    }
   public LogFileViewModel()
    {
        initializeload();
        timer.Tick += new EventHandler(timer_Tick);
        timer.Interval = new TimeSpan(0, 0, 3);
        timer.Start();
    }

    ~LogFileViewModel()
    {
        Dispose(false);
    }

    protected virtual void Dispose(bool disposing)
    {
        if (!disposed)
        {
            if (disposing)
            {
                timer.Stop();
                timer.Tick -= new EventHandler(timer_Tick);
            }
            disposed = true;
        }
    }

    private void timer_Tick(object sender, EventArgs e)
    {
        try
        {
            LogFileData.Clear();
            initializeload();
        }
        catch (Exception ex)
        {
            timer.Stop();
            Console.WriteLine(ex.Message);

        }
    }

    private void initializeload()
    {
        try
        {
            DataTable table = _myModel.getData();

            for (int i = 0; i < table.Rows.Count; ++i)
                LogFileData.Add(new LogFileModel
                {
                   HostID= Convert.ToInt32(table.Rows[i][0]),
                   LogID = table.Rows[i][1].ToString(),
                   LogPath = table.Rows[i][2].ToString(),
                   Date = Convert.ToDateTime(table.Rows[i][3]),
                   LastAcivity= table.Rows[i][4].ToString(),                   
                });
        }

        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string propertyname)
    {
        var handler = PropertyChanged;
        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyname));
    }

    public class LogModel
    {
        public DataTable getData()
        {
            DataTable ndt = new DataTable();
            SqlConnection sqlcon = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
            sqlcon.Open();
            SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM [LocalDB].[dbo].[LogFiles]", sqlcon);
            da.Fill(ndt);
            da.Dispose();
            sqlcon.Close();
            return ndt;
        }
    }
}

}

I have followed the same pattern for the Host Model and ViewModel too.

Answer 1

You will have to have the following in your code viewmodel

A SelectedItem which will hold the selected item in the first DataGrid.
A collection HostData that holds all of your hosts.
An empty collection Log Data which will display the logs for a particular host

//populate with all your hosts and this will bind to your first datagrid
private ObservableCollection<HostModel> _hostData= new ObservableCollection<Host>();

public ObservableCollection<HostModel> HostData
{
    get { return _hostData; }
    set { _hostData= value; OnPropertyChanged("HostData"); }
}

//populate with all the logs for the selected item and bind this to your second datagrid
private ObservableCollection<LogFileModel> _logFileData = new ObservableCollection<LogFileModel>();

public ObservableCollection<LogFileModel> LogFileData
{
    get { return _logFileData; }
    set { _logFileData = value; OnPropertyChanged("LogFileData"); }
}

//when the user selects an item in the first datagrid this property will hold the value
//so you will bind it to the selected item property of your first datagrid
private Host _selectedHost; //initialise to avoid null issues

public HostModelSelectedHost
{
    get{ return _selectedItem; } 
    set 
    {
        //call a method to populate you second collection
        _selectedHost = value;
        logFileData = GetLogsForSelectedHost(_selectedHost);
        OnPropertyChanged("SelectedHost");
    { 
}

//the method for populating your second collection could look like this
private ObservableCollection<LogFileModel> GetLogsForSelectedHost(_selectedHost)
{
    ObservableCollection<LogFileModel> filteredLogs = new ObservableCollection<LogFileModel>;

    filteredLogs = //fill the collection with all the logs that match the host ID of
                   //your selected item
    return filteredLogs ;
}

I am not sure from your code which class is which but I hope the code above can show you the way of doing this.