Commands

The DataForm enables you to control its behavior by customizing its available commands in an MVVM-friendly way.

DataFormCommandProvider

The DataForm provides the public DataFormCommandProvider class, which exposes the "execute" and "can-execute" logic for all its commands. The component processes these commands according to its current provider.

Execute Logic Methods

The "execute" logic methods identify the logic that is executed when a certain command is invoked.

Execute Logic Methods

• C#

void MoveCurrentToFirst(); 
void MoveCurrentToLast(); 
void MoveCurrentToNext(); 
void MoveCurrentToPrevious(); 
void BeginEdit(); 
void CommitEdit(); 
void Delete(); 
void CancelEdit(); 
void AddNew(); 

Can-Execute Logic Methods

The "can-execute" logic methods enable you to identify whether a certain command can be executed or not.

CanExecute Logic Methods

• C#

bool CanMoveCurrentToFirstExecute(); 
bool CanMoveCurrentToLastExecute(); 
bool CanMoveCurrentToNextExecute(); 
bool CanMoveCurrentToPreviousExecute(); 
bool CanBeginEditExecute(); 
bool CanCommitEditExecute(); 
bool CanDeleteExecute(); 
bool CanCancelEditExecute(); 
bool CanAddNewExecute(); 

Customizing the DataFormCommandProvider

To design and set a custom DataFormCommandProvider, follow the steps:

1. Create your own class that inherits from DataFormCommandProvider:

   Define a Custom CommandProvider

   • C#

       public class CustomCommandProvider : DataFormCommandProvider 
       { 
           public CustomCommandProvider() : base(null) 
           { 
           } 
           public CustomCommandProvider(RadDataForm dataForm) 
                   : base(dataForm) 
           { 
               this.DataForm = dataForm; 
           } 
           //. . . 
       } 

2. Override the methods of the commands that will be customized.

   The following example aims at changing the MoveCurrentToNext and MoveCurrentToPrevious execution logic to start editing the item immediately after it is set as a current one and bypass the logic in the same place.

   Customizing MoveCurrentToNext and MoveCurrentToPrevious

   • C#

       protected override void MoveCurrentToNext() 
       { 
           if (this.DataForm != null) 
           { 
               this.DataForm.MoveCurrentToNext(); 
               this.DataForm.BeginEdit(); 
           } 
       } 
       protected override void MoveCurrentToPrevious() 
       { 
           if (this.DataForm != null) 
           { 
               this.DataForm.MoveCurrentToPrevious(); 
               this.DataForm.BeginEdit(); 
           } 
       } 

   A common requirement for the DataForm is to add confirmation message boxes when CRUD operations are executed. The example below implements the scenario for the CommitEdit and CancelEdit commands.

   Customizing CommitEdit and CancelEdit

   • C#

       protected override void CommitEdit() 
       { 
           MessageBoxResult result = MessageBox.Show("Commit changes for the current edit item?", "CommitEdit confirmation", MessageBoxButton.OKCancel); 
           if (result == MessageBoxResult.OK) 
           { 
               if (this.DataForm != null && this.DataForm.ValidateItem()) 
               { 
                   this.DataForm.CommitEdit(); 
               } 
           } 
       } 
       protected override void CancelEdit() 
       { 
           MessageBoxResult result = MessageBox.Show("Cancel changes for the current edit item?", "CancelEdit confirmation", MessageBoxButton.OKCancel); 
           if (result == MessageBoxResult.OK) 
           { 
               if (this.DataForm != null) 
               { 
                   this.DataForm.CancelEdit(); 
               } 
           } 
       } 

3. The last thing to do is set the CommandProvider property of the DataForm to the newly-created CustomKeyboardCommandProvider class:

   Set the CommandProvider Property in XAML

   • XAML

       <Grid.Resources> 
           <my:CustomCommandProvider x:Key="CustomProvider"/> 
       </Grid.Resources> 
       <telerik:RadDataForm x:Name="RadDataForm1" 
                    ItemsSource="{Binding Employees}" 
                    CommandProvider="{StaticResource CustomProvider}"/> 

   Set the CommandProvider Property in Code

   • C#

       this.RadDataForm1.CommandProvider = new CustomCommandProvider(this.RadDataForm1); 

   Executing Commands Manually

By using the RadDataFormCommands class, you can set a sequence of commands that will be performed one after another. For example, you can handle the click event of a button, move to the next item, and place the DataForm it in edit mode. However, when invoking the commands in such a manner, you have to add a second parameter that points out the target UI element, as shown in the following example.

Executing a Sequence of Commands

• C#

private void Button1_Click(object sender, RoutedEventArgs e) 
{ 
    var moveToNextCommand = RadDataFormCommands.MoveCurrentToNext as RoutedUICommand; 
    var editCommand = RadDataFormCommands.BeginEdit as RoutedUICommand; 
    moveToNextCommand.Execute(null, this.DataForm); 
    editCommand.Execute(null, this.DataForm); 
}