Run MVVM user management method

Question

I am working on my first MVVM application and I am having problems with it working correctly.

In my main window, I have a button that executes an SQL command that returns an object like a data table.

The window also contains a user control consisting of column headers and Windows HostGridView forms. I need to somehow tell the user control to execute a method that passes data to the DataGridView so that it can update its values.

I tried to create a dependency property in my WPF grid control bound to the data in my view model, but it is not updating properly.

How can I make this work?

- EDIT -

Here is the XAML for my LiteGrid user control -

<UserControl x:Class="ReportUtility.Controls.LiteGrid.LiteGrid" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms" xmlns:lite="clr-namespace:ReportUtility.Controls.LiteGrid" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="300" DataContext="{Binding RelativeSource={RelativeSource Self}}"> <Grid> <Grid.RowDefinitions> <RowDefinition Height="30"/> <RowDefinition Height="*"/> </Grid.RowDefinitions> <ScrollViewer x:Name="_scroll" VerticalScrollBarVisibility="Hidden" HorizontalScrollBarVisibility="Hidden"> <ItemsControl ItemsSource="{Binding Columns}" Grid.Row="0" Background="AliceBlue"> <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <StackPanel Orientation="Horizontal"/> </ItemsPanelTemplate> </ItemsControl.ItemsPanel> </ItemsControl> </ScrollViewer> <WindowsFormsHost Background="White" Grid.Row="1"> <lite:LiteGridView x:Name="_liteGridView"/> </WindowsFormsHost> </Grid> 

My main view model:

 public class MainWindowViewModel : DependencyObject { private readonly ILiteTableSource _source; public ICommand ExecuteQueryCommand { get; set; } public LiteGridViewModel Grid { get; set; } public string SqlCommandText { get; set; } public MainWindowViewModel(ILiteTableSource source) { this.ExecuteQueryCommand = new ExecuteQueryCommand(this); _source = source; _source.DataArrived+=new Action<DataSources.LiteSource.LiteTable>(_source_DataArrived); } public void ExecuteQuery() { _source.Connection = new ServerConnection(); _source.CommandText = this.SqlCommandText; _source.ExecuteQuery(); } public LiteTable Results { get { return (LiteTable)GetValue(ResultsProperty); } set { SetValue(ResultsProperty, value); } } // Using a DependencyProperty as the backing store for Results. This enables animation, styling, binding, etc... public static readonly DependencyProperty ResultsProperty = DependencyProperty.Register("Results", typeof(LiteTable), typeof(MainWindowViewModel), new UIPropertyMetadata(null)); void _source_DataArrived(LiteTable data) { this.Results = data; } } 

And XAML:

 <Grid> <Grid.RowDefinitions> <RowDefinition Height="auto"/> <RowDefinition Height="50"/> <RowDefinition Height="*"/> </Grid.RowDefinitions> <Button Grid.Row="0" Content="TestButton" HorizontalAlignment="Stretch" Command="{Binding ExecuteQueryCommand}"/> <TextBox Grid.Row="1" Text="{Binding Path=SqlCommandText, UpdateSourceTrigger=PropertyChanged}"/> <lite:LiteGrid Grid.Row="2" Data="{Binding Data, UpdateSourceTrigger=PropertyChanged}"/> </Grid> 

Answer 1

Since you have a LiteGridViewModel to go with your LiteGrid , why not just execute the command from the ViewModel?

Using the code sent to your question, I would:

Add this to Resources to make LiteGridViewModel using LiteView

 <Window.Resources> <!-- Or Grid.Resources if you prefer --> <DataTemplate DataType="{x:Type lite:LiteGridViewModel}"> <lite:LiteGrid /> </DataTemplate> </Window.Resources> 

Replace the <lite:LiteGrid ... /> MainView in MainView with ContentControl to display the ViewModel

 <ContentControl Content="{Binding Grid}" /> 

Remove the Data property in MainViewModel , as it should be stored in LiteGridViewModel , not MainViewModel

And in your MainWindowViewModel work with LiteGridViewModel instead of trying to work with ViewModel through View

 Grid = new LiteGridViewModel(); void _source_DataArrived(LiteTable data) { Grid.Data = data; // Fill property in ViewModel Grid.UpdateData(); // Call command on ViewModel } 

Answer 2

 public LiteTable Data { get { return (LiteTable)GetValue(DataProperty); } set { object oldvalue = Data; SetValue(DataProperty, value); OnPropertyChanged(new DependencyPropertyChangedEventArgs(DataProperty, oldvalue, value)); } } // Using a DependencyProperty as the backing store for Data. This enables animation, styling, binding, etc... public static readonly DependencyProperty DataProperty = DependencyProperty.Register("Data", typeof(LiteTable), typeof(LiteGrid), new UIPropertyMetadata(null)); 

try it...