Lesson 3 - Post Changes to a Database

• Sep 28, 2021
• 2 minutes to read

This tutorial demonstrates how to edit data within the GridControl and save changes to the database. The tutorial is based on Lesson 2.

The Items Source Wizard adds data posting functionality when you enable the CRUD (Create, Read, Update, Delete) options.

The Items Source Wizard: generates the following code:

1. The TableView.ShowUpdateRowButtons property is set to OnCellEditorOpen. This turns on an edit mode that allows users to edit an entire row and then submit or cancel all changes at once:

   

2. The commands are generated at runtime from the methods with the attribute Command attached to them. A generated command name follows the [MethodName]Command pattern.

   The ValidateRow command saves newly added rows and changes to the existing ones back to the database:

   ViewModel.cs

   [Command]
   public void ValidateRow(RowValidationArgs args) {
       var item = (Order)args.Item;
       if (args.IsNewItem)
           _Context.Orders.Add(item);
       _Context.SaveChanges();
   }
   

   ViewModel.vb

   <Command>
   Public Sub ValidateRow(ByVal args As RowValidationArgs)
       Dim item = CType(args.Item, Order)
       If args.IsNewItem Then _Context.Orders.Add(item)
       _Context.SaveChanges()
   End Sub
   

   The ValidateRowDeletion command saves row deletion back to the database:

   ViewModel.cs

   [Command]
   public void ValidateRowDeletion(ValidateRowDeletionArgs args) {
       var item = (Order)args.Items.Single();
       _Context.Orders.Remove(item);
       _Context.SaveChanges();
   }
   

   ViewModel.vb

   <Command>
   Public Sub ValidateRowDeletion(ByVal args As ValidateRowDeletionArgs)
       Dim item = CType(args.Items.[Single](), Order)
       _Context.Orders.Remove(item)
       _Context.SaveChanges()
   End Sub
   

   The DataSourceRefresh command fetches changes from the database and updates the grid’s content:

   ViewModel.cs

   [Command]
   public void DataSourceRefresh(DataSourceRefreshArgs args) {
       _ItemsSource = null;
       _Context = null;
       RaisePropertyChanged(nameof(ItemsSource));
   }
   

   ViewModel.vb

   <Command>
   Public Sub DataSourceRefresh(ByVal args As DataSourceRefreshArgs)
       _ItemsSource = Nothing
       _Context = Nothing
       RaisePropertyChanged(NameOf(ItemsSource))
   End Sub
   

   The TableView‘s properties include bindings to the generated commands:

   MainWindow.xaml

   <dxg:GridControl ItemsSource="{Binding Orders}">
       <!-- ... -->
       <dxg:GridControl.View>
           <dxg:TableView NewItemRowPosition="Top"
               ShowUpdateRowButtons="OnCellEditorOpen"
               ValidateRowCommand="{Binding ValidateRowCommand}"
               ValidateRowDeletionCommand="{Binding ValidateRowDeletionCommand}"
               DataSourceRefreshCommand="{Binding DataSourceRefreshCommand}"/>
       </dxg:GridControl.View>
   </dxg:GridControl>