DataGrid and BindingValidationError

07-02-2009 5:26 AM |

Hi Guys!

I need to validate user-entry data in a Datagrid with customized DataTemplate (with textbox). On the web, I've found a lot of examples (like http://msdn.microsoft.com/en-us/library/cc278072(VS.95).aspx or http://weblogs.asp.net/manishdalal/archive/2008/08/28/silverlight-business-application-part-3-validation-sync.aspx) that suggests to change textbox properties NotifyOnValidationError and ValidatesOnExceptions, setting them "true". So, the GridView's event "BindingValidationError" could be directly managed.

This is my sample code:

Page.xaml
1    <UserControl xmlns:data="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Data"  x:Class="SilverlightApplication1.Page"
2        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4        Width="400" Height="300">
5        <Grid x:Name="LayoutRoot" Background="White">
6            <data:DataGrid x:Name="MyGrid" AutoGenerateColumns="False" Grid.Row="1" >
7                <data:DataGrid.Columns>
8                    <data:DataGridTemplateColumn Header="Valore">
9                        <data:DataGridTemplateColumn.CellTemplate>
10                           <DataTemplate>
11                               <TextBox Text="{Binding Path=Valore,Mode=TwoWay,NotifyOnValidationError=true,ValidatesOnExceptions=true}"  />
12                           </DataTemplate>
13                       </data:DataGridTemplateColumn.CellTemplate>
14                   </data:DataGridTemplateColumn>
15               </data:DataGrid.Columns>
16           </data:DataGrid>
17       </Grid>
18   </UserControl>

Page.xaml.cs
1    using System;
2    using System.Collections.Generic;
3    using System.Linq;
4    using System.Net;
5    using System.Windows;
6    using System.Windows.Controls;
7    using System.Windows.Documents;
8    using System.Windows.Input;
9    using System.Windows.Media;
10   using System.Windows.Media.Animation;
11  using System.Windows.Shapes;
12  
13   namespace SilverlightApplication1
14   {
15       public partial class Page : UserControl
16       {
17           public Page()
18           {
19               InitializeComponent();
20  
21               this.MyGrid.BindingValidationError += new EventHandler(MyGrid_BindingValidationError);
22               this.Loaded += new RoutedEventHandler(Page_Loaded);
23           }
24  
25           void Page_Loaded(object sender, RoutedEventArgs e)
26           {
27               MyGrid.ItemsSource = SilverlightApplication1.Valori.ValoriEsempio();
28  
29           }
30  
31           void MyGrid_BindingValidationError(object sender, ValidationErrorEventArgs e)
32           {
33               MessageBox.Show("Errore");
34           }
35       }
36   }

MyClass.cs
1    using System;
2    using System.Net;
3    using System.Windows;
4    using System.Windows.Controls;
5    using System.Windows.Documents;

6 using System.Windows.Ink;
7    using System.Windows.Input;
8    using System.Windows.Media;
9    using System.Windows.Media.Animation;
10   using System.Windows.Shapes;
11   using System.ComponentModel;
12   using System.Collections.ObjectModel;
13  
14   namespace SilverlightApplication1
15   {
16       public class MyClass : INotifyPropertyChanged
17       {
18           protected int _Valore;
19           public int Valore
20           {
21               get { return _Valore; }
22               set
23               {
24                   if (value == _Valore) return;
25                   if (value < 0 || value > 200)
26                   {
27                       throw new Exception("Valore non nel range specificato");
28                   }
29                   _Valore = value;
30                   OnPropertyChanged("Valore");
31               }
32           }
33  
34           #region INotifyPropertyChanged Membri di
35  
36           protected void OnPropertyChanged(string name)
37           {
38               if (PropertyChanged != null)
39                   PropertyChanged(this, new PropertyChangedEventArgs(name));
40           }
41           public event PropertyChangedEventHandler PropertyChanged;
42  
43           #endregion
44       }
45  
46  
47       public class Valori : ObservableCollection
48       {
49           public static Valori ValoriEsempio()
50           {
51               return new Valori() {
52               new MyClass() { Valore=30},
53               new MyClass() { Valore=40},
54               new MyClass() { Valore=50},
55               new MyClass() { Valore=20},
56               new MyClass() { Valore=10},
57           };
58           }
59       }
60   }

When I change the textbox to a out-of-range value, MyGrid_BindingValidationError isn't executed. Why?
Thank you very much

--
Simone Viganò AKA VeroToad - MVP Windows Desktop Experience
My blog: http://blogs.dotnethell.it/VeroToad
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