Raising event in custom control - wpf

I'm writing a custom textblock control thats populate hyperlinks and raises event when clicked to hyperlink.
I wrote this code but I got stucked.
My code is :
Imports System.Text.RegularExpressions
Public Class CustomTextBlock
Inherits TextBlock
Public Event Klik As EventHandler(Of EventArgs)
Public ReadOnly InlineCollectionProperty As DependencyProperty = DependencyProperty.Register("InlineCollection", GetType(String), GetType(CustomTextBlock), New PropertyMetadata(New PropertyChangedCallback(AddressOf CustomTextBlock.InlineChanged)))
Private Shared Sub InlineChanged(ByVal sender As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
DirectCast(sender, CustomTextBlock).Inlines.Clear()
Dim kelimeler = Split(e.NewValue, " ")
For i = 0 To kelimeler.Length - 1
If Regex.Match(kelimeler(i), "(http|ftp|https):\/\/[\w\-_]+(\.[\w\-_]+)+([\w\-\.,#?^=%&:/~\+#]*[\w\-\#?^=%&/~\+#])?").Success Then
Dim x = New Hyperlink(New Run(kelimeler(i)))
x.AddHandler(Hyperlink.ClickEvent, New RoutedEventHandler(AddressOf t_Click))
x.ToolTip = kelimeler(i)
x.Tag = kelimeler(i)
DirectCast(sender, CustomTextBlock).Inlines.Add(x)
If Not i = kelimeler.Length Then DirectCast(sender, CustomTextBlock).Inlines.Add(" ")
Else
DirectCast(sender, CustomTextBlock).Inlines.Add(kelimeler(i))
If Not i = kelimeler.Length Then DirectCast(sender, CustomTextBlock).Inlines.Add(" ")
End If
''//Console.WriteLine(kelime(i).ToString.StartsWith("#"))
Next
kelimeler = Nothing
End Sub
Public Property InlineCollection As String
Get
Return DirectCast(GetValue(InlineCollectionProperty), String)
End Get
Set(ByVal value As String)
SetValue(InlineCollectionProperty, value)
End Set
End Property
Private Shared Sub t_Click(ByVal sender As Hyperlink, ByVal e As System.Windows.RoutedEventArgs)
e.Handled = True
RaiseEvent Klik(sender, EventArgs.Empty)
End Sub
End Class
This code gives error at RaiseEvent Klik(sender, EventArgs.Empty)
Error is : Cannot refer to an instance member of a class from within a shared method or shared member initializer without an expliticit instance of the class.
Thanks for your answers,
Alper

The problem is clearly stated in the exception message. The t_Click method is Shared (which means common to all instances of the class), so it cannot raise an Event that is specific to an instance of the class. You should only raise the event from a method that is not shared.

Do something like this -
Imports System
Imports System.Text.RegularExpressions
Public Class CustomTextBlock
Inherits TextBlock
Public Event Klik As EventHandler(Of System.EventArgs)
Public ReadOnly InlineCollectionProperty As DependencyProperty = DependencyProperty.Register("InlineCollection", GetType(String), GetType(CustomTextBlock), New PropertyMetadata(New PropertyChangedCallback(AddressOf CustomTextBlock.InlineChanged)))
Private Shared Sub InlineChanged(ByVal sender As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
Dim d As CustomTextBlock = DirectCast(sender, CustomTextBlock)
d.Inlines.Clear()
d.OnInlineChanged(CType(e.NewValue, String))
End Sub
Private Sub OnInlineChanged(ByVal Value As String)
Dim kelimeler = Split(Value, " ")
For i As Integer = 0 To kelimeler.Length - 1
If Regex.Match(kelimeler(i), "(http|ftp|https):\/\/[\w\-_]+(\.[\w\-_]+)+([\w\-\.,#?^=%&:/~\+#]*[\w\-\#?^=%&/~\+#])?").Success Then
Dim x = New Hyperlink(New Run(kelimeler(i)))
x.AddHandler(Hyperlink.ClickEvent, New RoutedEventHandler(AddressOf t_Click))
x.ToolTip = kelimeler(i)
x.Tag = kelimeler(i)
Me.Inlines.Add(x)
If Not i = kelimeler.Length Then Me.Inlines.Add(" ")
Else
Me.Inlines.Add(kelimeler(i))
If Not i = kelimeler.Length Then Me.Inlines.Add(" ")
End If
''//Console.WriteLine(kelime(i).ToString.StartsWith("#"))
Next
kelimeler = Nothing
End Sub
Public Property InlineCollection As String
Get
Return DirectCast(GetValue(InlineCollectionProperty), String)
End Get
Set(ByVal value As String)
SetValue(InlineCollectionProperty, value)
End Set
End Property
Private Sub t_Click(ByVal sender As Hyperlink, ByVal e As System.Windows.RoutedEventArgs)
e.Handled = True
RaiseEvent Klik(sender, System.EventArgs.Empty)
End Sub
End Class

Related

Error while checking row, after Filtering observational collection

I'm having trouble with editing an observable collection... I bind columns in codebehind like so...
Dim dgCheckBoxColumn As New DataGridCheckBoxColumn()
Dim column_username As New DataGridTextColumn()
Dim textColumn2 As New DataGridTextColumn()
Dim textColumn3 As New DataGridTextColumn()
dgCheckBoxColumn.Header = "Selected"
dgCheckBoxColumn.Binding = New Binding("Selected")
dgvResults.Columns.Add(dgCheckBoxColumn)
column_username.Header = "User Name"
column_username.Binding = New Binding("accountName")
dgvResults.Columns.Add(column_username)
textColumn2.Header = "First Name"
textColumn2.Binding = New System.Windows.Data.Binding("firstName")
dgvResults.Columns.Add(textColumn2)
textColumn3.Header = "Last Name"
textColumn3.Binding = New System.Windows.Data.Binding("lastName")
dgvResults.Columns.Add(textColumn3)
Then I create my observablecollection...
Dim oc_userlist As New ObservableCollection(Of user)
Imports System.ComponentModel
Public Class user
Implements INotifyPropertyChanged
Private m_accountname As String
Private m_firstname As String
Private m_lastname As String
Private _Selected As Boolean
Public Property Selected() As Boolean
Get
Return _Selected
End Get
Set(value As Boolean)
_Selected = value
NotifyPropertyChanged("IsChecked")
End Set
End Property
Public Property accountName() As String
Get
Return m_accountname
End Get
Set(value As String)
m_accountname = value
End Set
End Property
Public Property firstName() As String
Get
Return m_firstname
End Get
Set(value As String)
m_firstname = value
End Set
End Property
Public Property lastName() As String
Get
Return m_lastname
End Get
Set(value As String)
m_lastname = value
End Set
End Property
#Region "INotifyPropertyChanged Members"
Public Event PropertyChanged As PropertyChangedEventHandler _
Implements INotifyPropertyChanged.PropertyChanged
#End Region
#Region "Private Helpers"
Private Sub NotifyPropertyChanged(propertyName As String)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
End Sub
#End Region
End Class
Then I add new user to collection, like so...
oc_userlist.Add(New user With { _
.Selected = False, _
.accountName = "awiles", _
.firstName = "Anthony", _
.lastName = "Wiles"
})
I'm trying to filter using a textbox, with the textchanged event, and it's working wonderfully...
Private Sub TextBox_TextChanged(sender As Object, e As TextChangedEventArgs)
Dim result = oc_userlist.Where(Function(w) w.accountName.Contains(txtFilter.Text.ToString) _
Or w.firstName.Contains(txtFilter.Text.ToString) _
Or w.lastName.Contains(txtFilter.Text.ToString))
dgvResults.ItemsSource = result
End Sub
The problem I'm having is once this is filtered, using the textbox, then I try to select something, it tells me
'EditItem' is not allowed for this view.
I'm having issues trying to get around this issue, can anybody point me in the correct direction?
The reason could be the result of your Linq query (with the Where) is not a List(Of T) but an IEnumerable.
Try adding a call to ToList()
Dim result = oc_userlist.Where(Function(w) w.accountName.Contains(txtFilter.Text.ToString) _
Or w.firstName.Contains(txtFilter.Text.ToString) _
Or w.lastName.Contains(txtFilter.Text.ToString)) _
.ToList()
Then tell if it works

WPF VB.NET 4.0 DatagridComboBoxColumn binding at runtime

I had a similar question for DatagridComboboxColumn but that shown me how to use the .itemsource to bind to an array outside of the datagrid. I am having a problem trying to bind to the collection that the datagrid is bound to at runtime.
I have included a working test program for how I am approaching this.
Class MainWindow
Dim ServerInfoArray As List(Of ServerInfo) = New List(Of ServerInfo)
Private Sub GetInfo(ByVal list As List(Of String))
For Each server As String In list
Dim tempip As ComboBoxItem = New ComboBoxItem
Dim tempip2 As ComboBoxItem = New ComboBoxItem
Dim sinfo As ServerInfo = New ServerInfo
tempip.Content = "192.129.123.23"
tempip2.Content = "23.213.223.21"
sinfo.IPArray.Items.Add(tempip)
sinfo.IPArray.Items.Add(tempip2)
sinfo.ServerName = server
ServerInfoArray.Add(sinfo)
DataGrid1.Items.Refresh()
Next
End Sub
Private Sub Button1_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles Button1.Click
Dim serverlist As List(Of String) = New List(Of String)
serverlist.Add("Test")
serverlist.Add("Random")
serverlist.Add("Local")
GetInfo(serverlist)
End Sub
Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
Dim Col_Serial As DataGridTextColumn = New DataGridTextColumn()
Col_Serial.Binding = New Binding("Servername")
Col_Serial.Header = "Servername"
Col_Serial.Width = 40
Dim Col_IPArray = New DataGridComboBoxColumn()
Col_IPArray.Header = "IP Addresses"
Col_IPArray.IsReadOnly = True
'Col_IPArray.ItemsSource = serverInfoArray ' Don't know how to do this.
Col_IPArray.SelectedValuePath = "IPArray"
Col_IPArray.DisplayMemberPath = "IPArray"
DataGrid1.Columns.Add(Col_Serial)
DataGrid1.Columns.Add(Col_IPArray)
DataGrid1.ItemsSource = ServerInfoArray
End Sub
End Class
Class ServerInfo
Dim _Servername As String
Dim _IPArray As ComboBox
Public Property Servername() As String
Get
Return _Servername
End Get
Set(ByVal value As String)
_Servername = value
End Set
End Property
Public Property IPArray As ComboBox
Get
Return _IPArray
End Get
Set(ByVal value As ComboBox)
_IPArray = value
End Set
End Property
Public Sub New()
_Servername = Nothing
_IPArray = New ComboBox
End Sub
End Class
I can get all Strings and Boolean to bind.
I do not know how I can bind this DataGridComboBoxColumn to the list of attached on the property. I cannot use XAML as I need to do this at runtime.
Dim Col_Serial As DataGridComboColumn = New DataGridComboColumn()
Col_Serial.ItemSource = GetData();
Col_Serial.SelectedValuePath = "ID_value";
Col_Serial.DisplayMemberPath = "displya_col";
Col_Serial.Header = "Disk4"
Col_Serial.Width = 40
Col_Serial.IsEnabled= false;
dg.Columns.Add(Col_serial);

WPF Datagrid DataGridComboBoxColumn Autogenerate at runtime

I have a datagrid in my vb.net 4.0 wpf project. I have seen many examples in XAML on how to bind a DataGridComboBoxColumn however I need to do this in code as I have auto-generating columns. I switch the datagridbinding source to multiple data sets.
Inside some of these custom classes are a couple lists. I can get text and checkboxes to auto-generate correctly. When it comes across my array (I have tried many different kinds) I just see a textboxcolumn with the words (Collection) in it.
For instance - One screen I am grabbing system information on WMI calls. One of the calls returns all IP addresses on the server (We can have up to 8 IP addresses) I do not want a column per IP address. I would like to include a list of those into the datagrid so you can drop down and see them.
Any suggestions on if this is possible or if I am doing something wrong?
Thank you
Sample Code
Imports System.Collections.ObjectModel
Class MainWindow
Dim ServerInfoArray As ObservableCollection(Of ServerInfo) = New ObservableCollection(Of ServerInfo)
Private ReadOnly _ipAddresses As ObservableCollection(Of String) = New ObservableCollection(Of String)
Private Sub GetInfo(ByVal list As List(Of String))
For Each server As String In list
Dim tempip As List(Of String) = New List(Of String)
Dim sinfo As ServerInfo = New ServerInfo
tempip.Add("192.129.123.23")
tempip.Add("23.213.223.21")
sinfo.IPArray = tempip
sinfo.Servername = server
ServerInfoArray.Add(sinfo)
Next
End Sub
Private Sub Button1_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles Button1.Click
Dim serverlist As List(Of String) = New List(Of String)
serverlist.Add("Test")
serverlist.Add("Random")
serverlist.Add("Local")
GetInfo(serverlist)
End Sub
Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
Dim Col_Serial As DataGridTextColumn = New DataGridTextColumn()
Col_Serial.Binding = New Binding("Servername")
Col_Serial.Header = "Servername"
Col_Serial.Width = 40
Dim Col_IPArray = New DataGridComboBoxColumn()
Col_IPArray.Header = "IP Addresses"
Col_IPArray.IsReadOnly = True
Col_IPArray.ItemsSource = Me._ipAddresses
Col_IPArray.SelectedItemBinding = New Binding("IPArray")
DataGrid1.Columns.Add(Col_Serial)
DataGrid1.Columns.Add(Col_IPArray)
DataGrid1.ItemsSource = ServerInfoArray
End Sub
End Class
Class ServerInfo
Dim _Servername As String
Dim _IPArray As List(Of String)
Public Property Servername() As String
Get
Return _Servername
End Get
Set(ByVal value As String)
_Servername = value
End Set
End Property
Public Property IPArray As List(Of String)
Get
Return _IPArray
End Get
Set(ByVal value As List(Of String))
_IPArray = value
End Set
End Property
Public Sub New()
_Servername = Nothing
_IPArray = New List(Of String)
End Sub
End Class
Not sure if I am understanding perfectly but if you can live with AutoGenerateColumns = False then you can manipulate the columns, their properties and bindings from code like below. So you could use whatever logic you need to in order setup the columns from code. I tried to show how you can source the combobox column items from a different object than the items in the DataGrid as well.
This is meant to be a simple example so I just did everything in the code-behind but from an MVVM standpoint, it depends on your preferred approach but possibility is that you could accomplish the same logic from a controller class that spins up your view models, etc...
Hope it helps!
XAML...
<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<StackPanel>
<Button x:Name="btnRefreshIPList">Refresh list of IPs</Button>
<DataGrid x:Name="dataGrid1"></DataGrid>
</StackPanel>
</Window>
Code behind...
Imports System.Collections.ObjectModel
Class MainWindow
'The list of IPs for column's ItemSource property
Private ReadOnly _ipAddresses As ObservableCollection(Of String)
'The items for binding to the DataGrid's ItemsSource
Private _items As List(Of MyObjectWithIPAddress)
Public Sub New()
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
_ipAddresses = New ObservableCollection(Of String)
_items = New List(Of MyObjectWithIPAddress)
End Sub
Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
Me.dataGrid1.AutoGenerateColumns = False
dataGrid1.Columns.Clear()
'Example of text column (Text bound to Name property)
Dim dgTxtCol = New DataGridTextColumn()
dgTxtCol.Header = "Name"
dgTxtCol.Binding = New Binding("Name")
dataGrid1.Columns.Add(dgTxtCol)
'Example of combobox column (SelectedItem bound to IPAddress)
Dim dgCmbCol = New DataGridComboBoxColumn()
dgCmbCol.Header = "IP Address"
dgCmbCol.ItemsSource = Me._ipAddresses
dgCmbCol.SelectedItemBinding = New Binding("IPAddress")
dataGrid1.Columns.Add(dgCmbCol)
'Add items to DataGrid
_items.Add(New MyObjectWithIPAddress("foo1"))
_items.Add(New MyObjectWithIPAddress("foo2"))
Me.dataGrid1.ItemsSource = Me._items
End Sub
''' <summary>
''' To emulate fetching the object that has the IP list
''' </summary>
''' <returns></returns>
''' <remarks></remarks>
Private Function GetIpList() As MyObjectWithListOfIPs
Dim inst = New MyObjectWithListOfIPs
inst.IPList = New List(Of String)(New String() {"10.0.0.1", "10.0.0.2", "10.0.0.3"})
Return inst
End Function
''' <summary>
''' Updates the ObservableCollection instance based on business object
''' </summary>
''' <remarks></remarks>
Private Sub RefreshIpAddresses()
_ipAddresses.Clear()
For Each ip As String In GetIpList().IPList
_ipAddresses.Add(ip)
Next
End Sub
Private Sub btnRefreshIPList_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles btnRefreshIPList.Click
RefreshIpAddresses()
End Sub
End Class
''' <summary>
''' Object with response data (e.g., list of IPs)
''' </summary>
''' <remarks></remarks>
Class MyObjectWithListOfIPs
Private _ipList As List(Of String)
Public Property IPList() As List(Of String)
Get
Return _ipList
End Get
Set(ByVal value As List(Of String))
_ipList = value
End Set
End Property
End Class
''' <summary>
''' Disperate object that "has an" address
''' </summary>
''' <remarks></remarks>
Class MyObjectWithIPAddress
Public Sub New(name As String)
Me._name = name
End Sub
Private _name As String
Public Property Name() As String
Get
Return _name
End Get
Set(ByVal value As String)
_name = value
End Set
End Property
Private _ipAddress As String
Public Property IPAddress() As String
Get
Return _ipAddress
End Get
Set(ByVal value As String)
_ipAddress = value
End Set
End Property
End Class

WPF AttachedCommandsBehavior in VB.NET

Can anybody give me an example how to implement AttachedCommands?
There are some examples in C# and I think it is very similar to C# but I have problems to translate the code to VB.NET.
At the moment my try to translate a C# AttachedCommand-Class to VB.net looks like that:
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Windows
Imports System.Windows.Input
Imports System.Reflection
Public Class AttachedCommand
Inherits DependencyObject
#Region "CommandParameter-Class"
Private NotInheritable Class CommandParameter
Public Shared ReadOnly Property DefaultCP() As CommandParameter
Get
Return New CommandParameter()
End Get
End Property
Private _command As ICommand
Public Property Command() As ICommand
Get
Return _command
End Get
Set(ByVal value As ICommand)
_command = value
End Set
End Property
Private _eventName As String
Public Property EventName() As String
Get
Return _eventName
End Get
Set(ByVal value As String)
_eventName = value
End Set
End Property
Private _callBack As [Delegate]
Public Property Callback() As [Delegate]
Get
Return _callBack
End Get
Set(ByVal value As [Delegate])
_callBack = value
End Set
End Property
End Class
#End Region
#Region "Properties"
Private Shared _parameter As IDictionary(Of DependencyObject, CommandParameter)
Private Shared Property Parameter() As IDictionary(Of DependencyObject, CommandParameter)
Get
Return _parameter
End Get
Set(ByVal value As IDictionary(Of DependencyObject, CommandParameter))
_parameter = value
End Set
End Property
Public Property Command() As ICommand
Get
Return GetValue(CommandProperty)
End Get
Set(ByVal value As ICommand)
SetValue(CommandProperty, value)
End Set
End Property
Public Shared ReadOnly CommandProperty As DependencyProperty = _
DependencyProperty.Register("Command", _
GetType(ICommand), GetType(AttachedCommand), _
New UIPropertyMetadata(AddressOf CommandChanged))
Public Property EventName() As String
Get
Return GetValue(EventNameProperty)
End Get
Set(ByVal value As String)
SetValue(EventNameProperty, value)
End Set
End Property
Public Shared ReadOnly EventNameProperty As DependencyProperty = _
DependencyProperty.Register("EventName", _
GetType(String), GetType(AttachedCommand), _
New UIPropertyMetadata(AddressOf EventNameChanged))
#End Region
#Region "Event-Handler"
Public Shared Sub CommandChanged(ByVal dependencyObject As DependencyObject, ByVal args As DependencyPropertyChangedEventArgs)
If Not Parameter.ContainsKey(dependencyObject) Then
Parameter.Add(dependencyObject, CommandParameter.DefaultCP)
End If
If (Not Parameter(dependencyObject).Callback = Nothing) AndAlso (Not args.OldValue = Nothing) Then
_RemoveEventHandler(dependencyObject)
End If
Parameter(dependencyObject).Command = CType(args.NewValue, ICommand)
_AttachEventHandler(dependencyObject)
End Sub
Public Shared Sub EventNameChanged(ByVal dependencyObject As DependencyObject, ByVal args As DependencyPropertyChangedEventArgs)
If Not Parameter.ContainsKey(dependencyObject) Then
Parameter.Add(dependencyObject, CommandParameter.DefaultCP)
End If
End Sub
#End Region
#Region "Helper"
Private Shared Sub _RemoveEventHandler(ByVal dependencyObject As DependencyObject)
If dependencyObject Is Nothing Then
Throw New ArgumentNullException("DependencyObject is null.")
End If
If Not Parameter.ContainsKey(dependencyObject) Then
Exit Sub
End If
Dim param As CommandParameter = Parameter(dependencyObject)
If param.Callback Is Nothing Then
Throw New InvalidProgramException("Cannot remove Callback. Callback is null.")
End If
Dim eventInfo As EventInfo = dependencyObject.GetType().GetEvent(param.EventName)
If eventInfo Is Nothing Then
Throw New InvalidProgramException(String.Format("Cannot find an event with the name <{0}>", param.EventName))
End If
eventInfo.RemoveEventHandler(dependencyObject, param.Callback)
End Sub
Private Shared Sub _AttachEventHandler(ByVal dependencyObject)
If dependencyObject Is Nothing Then
Throw New ArgumentNullException("DependencyObject is null")
End If
If Not Parameter.ContainsKey(dependencyObject) Then
Exit Sub
End If
Dim param As CommandParameter = Parameter(dependencyObject)
If param.Command Is Nothing Or String.IsNullOrEmpty(param.EventName) Then
Exit Sub
End If
Dim eventInfo As EventInfo = dependencyObject.GetType.GetEvent(param.EventName)
If eventInfo Is Nothing Then
Throw New InvalidProgramException(String.Format("Cannot find an event with the name <{0}>", param.EventName))
End If
eventInfo.AddEventHandler(dependencyObject, param.Callback)
End Sub
Private Shared Sub _CommandExecutAction(ByVal parameter As CommandParameter)
parameter.Command.Execute(Nothing)
End Sub
Private Shared Function _CreateHandler(ByVal eventInfo As EventInfo, ByVal method As Action) As [Delegate]
If eventInfo Is Nothing Then
Throw New ArgumentNullException("EventInfo is null")
End If
If method Is Nothing Then
Throw New ArgumentNullException("Action-method is null")
End If
Dim handlerType = eventInfo.EventHandlerType
Dim eventParams = handlerType.GetMethod("Invoke").GetParameters()
Dim parameters = eventParams.[Select](Function(p) System.Linq.Expressions.Expression.Parameter(p.ParameterType, "x"))
Dim body = System.Linq.Expressions.Expression.[Call](System.Linq.Expressions.Expression.Constant(method), method.[GetType]().GetMethod("Invoke"))
Dim lambda = System.Linq.Expressions.Expression.Lambda(body, parameters.ToArray())
Return [Delegate].CreateDelegate(handlerType, lambda.Compile(), "Invoke", False)
End Function
#End Region
#Region "INIT"
Public Sub New()
Parameter = New Dictionary(Of DependencyObject, CommandParameter)()
End Sub
#End Region
End Class
But now I have the problem, that the GetValue() and SetValue()-methods are not available. Any ideas?
Thank you for your help..
An AttachedCommandBehaviour ain't much more than an dependency property of type ICommand, which hookes some events.
Check out Dr. WPFs VB-snippets that includes snippets for dependency properties.
If you use the one that includes a property changed handler, you can use this handler to hook the events you want. In the event handler, you call the attached command.
If you still can't make it work, please post some code.

Is there a way to prevent a user selecting another row when DataGrid is in edit mode?

I want, that if a cell/row goes to edit mode, then, if the user attempts to select a different row, it should try to commit that row, if the row is not committed sucessfully, it should decline the selection request and the editing row should remain selected and in edit mode.
Do you have experience with a good helper for it? any good workaround?
NOTE: I've been struggling with this issue for a long time and already got some experience, so please post only working examples, not random thoughts.
The code bellow is includes extension from here (code normalized to fit StackOverflow screen witdh, sorry).
Imports System.ComponentModel
Imports System.Windows.Threading
Namespace Components
Public NotInheritable Class DataGridSelectionChangingBehavior
Public Shared Function GetEnableSelectionChanging(
ByVal element As DataGrid) As Boolean
If element Is Nothing Then Throw New ArgumentNullException("element")
Return element.GetValue(EnableSelectionChangingProperty)
End Function
Public Shared Sub SetEnableSelectionChanging(
ByVal element As DataGrid, ByVal value As Boolean)
If element Is Nothing Then Throw New ArgumentNullException("element")
element.SetValue(EnableSelectionChangingProperty, value)
End Sub
Public Shared ReadOnly EnableSelectionChangingProperty As _
DependencyProperty =
DependencyProperty.RegisterAttached("EnableSelectionChanging",
GetType(Boolean),
GetType(DataGridSelectionChangingBehavior),
New FrameworkPropertyMetadata(False,
New PropertyChangedCallback(
AddressOf EnableSelectionChanging_PropertyChanged)))
Public Shared Sub AddSelectionChangingHandler(
ByVal element As DataGrid, handler As SelectionChangingEventHandler)
If element IsNot Nothing Then _
element.AddHandler(
DataGridSelectionChangingBehavior.SelectionChangingEvent, handler)
End Sub
Public Shared Sub RemoveSelectionChangingHandler(
ByVal element As DataGrid, handler As SelectionChangingEventHandler)
If element IsNot Nothing Then _
element.RemoveHandler(
DataGridSelectionChangingBehavior.SelectionChangingEvent, handler)
End Sub
Public Shared ReadOnly SelectionChangingEvent As RoutedEvent =
EventManager.RegisterRoutedEvent("SelectionChanging",
RoutingStrategy.Bubble,
GetType(SelectionChangingEventHandler),
GetType(DataGridSelectionChangingBehavior))
Private Shared Sub EnableSelectionChanging_PropertyChanged(
ByVal sender As Object, ByVal e As DependencyPropertyChangedEventArgs)
Dim dataGrid = DirectCast(sender, DataGrid)
If CBool(e.NewValue) Then
AddHandler dataGrid.PreparingCellForEdit,
AddressOf DataGrid_PreparingCellForEdit
AddHandler dataGrid.SelectionChanged,
AddressOf DataGrid_SelectionChanged
Else
RemoveHandler dataGrid.PreparingCellForEdit,
AddressOf DataGrid_PreparingCellForEdit
RemoveHandler dataGrid.SelectionChanged,
AddressOf DataGrid_SelectionChanged
RecentColumn.Remove(dataGrid)
End If
End Sub
Private Shared Sub DataGrid_SelectionChanged(
ByVal sender As Object, ByVal e As SelectionChangedEventArgs)
If e.RemovedItems.Count = 0 Then Exit Sub
Dim dataGrid = DirectCast(sender, DataGrid)
Dim removed = e.RemovedItems(0)
Dim row = dataGrid.GetContainerFromItem(Of DataGridRow)(removed)
Dim scea As New SelectionChangingEventArgs(row,
DataGridSelectionChangingBehavior.SelectionChangingEvent, dataGrid)
dataGrid.RaiseEvent(scea)
If scea.Cancel Then
RemoveHandler dataGrid.SelectionChanged,
AddressOf DataGrid_SelectionChanged
Dim operation = dataGrid.Dispatcher.BeginInvoke(
Sub()
dataGrid.SelectedItem = removed
Dim column As DataGridColumn = Nothing
If RecentColumn.TryGetValue(dataGrid, column) Then
Dim cellsPanel =
row.GetVisualDescendant(Of DataGridCellsPanel)().
Children.Cast(Of DataGridCell)()
Dim recentCell =
If(cellsPanel.SingleOrDefault(
Function(cell) cell.Column Is column),
cellsPanel.FirstOrDefault)
If recentCell IsNot Nothing Then
recentCell.IsEditing = True
Keyboard.Focus(recentCell)
End If
End If
End Sub,
DispatcherPriority.ContextIdle)
AddHandler operation.Completed,
Sub(s, ea) AddHandler dataGrid.SelectionChanged,
AddressOf DataGrid_SelectionChanged
End If
End Sub
Private Shared m_RecentColumn As Dictionary(Of DataGrid, DataGridColumn)
Public Shared ReadOnly Property RecentColumn() As Dictionary(Of DataGrid,
DataGridColumn)
Get
If m_RecentColumn Is Nothing Then m_RecentColumn =
New Dictionary(Of DataGrid, DataGridColumn)()
Return m_RecentColumn
End Get
End Property
Private Shared Sub DataGrid_PreparingCellForEdit(
ByVal sender As Object, e As DataGridPreparingCellForEditEventArgs)
Dim dataGrid = DirectCast(sender, DataGrid)
RecentColumn(dataGrid) = e.Column
End Sub
End Class
Public Delegate Sub SelectionChangingEventHandler(
ByVal sender As Object, ByVal e As SelectionChangingEventArgs)
Public Class SelectionChangingEventArgs : Inherits RoutedEventArgs
Public Sub New(ByVal row As DataGridRow, routedEvent As RoutedEvent)
MyBase.New(routedEvent)
m_CurrentRow = row
End Sub
Public Sub New(ByVal row As DataGridRow,
ByVal routedEvent As RoutedEvent,
ByVal source As Object)
MyBase.New(routedEvent, source)
m_CurrentRow = row
End Sub
Private m_CurrentRow As DataGridRow
Public ReadOnly Property CurrentRow() As DataGridRow
Get
Return m_CurrentRow
End Get
End Property
Public ReadOnly Property Item() As Object
Get
If CurrentRow IsNot Nothing Then Return CurrentRow.Item
Return Nothing
End Get
End Property
Public Property Cancel As Boolean
End Class
End Namespace
Usage:
<DataGrid Name="dg"
src:DataGridSelectionChangingBehavior.EnableSelectionChanging="True"
src:DataGridSelectionChangingBehavior.SelectionChanging="dg_SelectionChanging">
Code behind (pseudu):
Private Sub dg_SelectionChanging(ByVal sender As Object,
ByVal e As SelectionChangingEventArgs)
If e.CurrentRow.IsEditing Then
Dim item = TryCast(e.CurrentRow.Item, MyEntityType)
If item IsNot Nothing AndAlso item.IsValid Then
Dim dataGrid = DirectCast(sender, DataGrid)
Dim committed = dataGrid.CommitEdit(DataGridEditingUnit.Row, True)
If committed Then Exit Sub
End If
e.Cancel = True
End If
End Sub
Note: visual studio might not show the event in the intellisense and might even generate a design-time error, but it should compile and work perfect.
FYI: code formatted modified to fit SO screen.

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