Tough Dynamic DataGrid Problem

G

Glenn Owens

OK, I'm stumped.

I've created a "simple" test web page (w/ code-behind) which does the
following:

Accepts a date criteria from the User (me) and has a asp:Button
"Submit"

On Submit the page creates, and adds, a dynamic DataGrid to the
control collection. The DataGrid has a "click-anywhere-on-a-row"
capability.

This all work well. The data is retrieved/displayed and, clicking a
DataGrid row, fires up the postback. The problem is that I had added
an event handler for the datagrid's SelectedIndexChanged event - which
doesn't fire.

I realize that I need to insure that the dynamic DataGrid is created
to support the SelectedIndexChanged event on Postback. To that end
I've saved the SQL SELECT statment (used to create/populate the
DataGrid in the ViewState. I've also overridden the LoadViewState
method (because it's before the Load_Page event) to call my "BindData"
method to create/bind the DataGrid.

Unfortunately, none of this results in the firing of the
SelectedIndexchanged event. I'm submitting the code with this post (in
hopes that it will clarify what I'm trying to do).

Please... I've taken these steps to try to solve the same issue in my
"real", time-critical app. Anyone who's got some experience with
Dynamic controls, the event model and the dreaded Postback please
HELP!!!

================================================
================================================
Public Class Test
Inherits AppBasePage

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub
Protected WithEvents tbxDate As System.Web.UI.WebControls.TextBox
Protected WithEvents lblDate As System.Web.UI.WebControls.Label
Protected WithEvents btnSubmit As System.Web.UI.WebControls.Button
Protected WithEvents lblMessage As System.Web.UI.WebControls.Label

'NOTE: The following placeholder declaration is required by the
Web Form Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form
Designer
'Do not modify it using the code editor.
InitializeComponent()

End Sub

#End Region

Private DisbTransDlo As DloDisbTrans

Private Sub Page_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load

If Not Page.IsPostBack Then
tbxDate.Text =
DateTime.Today.AddDays(-1).ToShortDateString
End If
End Sub

Private Sub BindData()
If DisbTransDlo Is Nothing Then
DisbTransDlo = New
DloDisbTrans(Me.GetConnection(Me._NPDISB))
End If

Me.Controls.Add(CreateDataGrid())
End Sub

Private Function CreateDataGrid() As MyDataGrid
Dim dg As New MyDataGrid

dg.AutoGenerateColumns = True
dg.DataSource = DisbTransDlo.RetrieveDataTable("sqlMonitor_0",
_
Me.ViewState("where").ToString)
dg.ID = "Testing"
dg.HeaderStyle.BackColor = System.Drawing.Color.LightBlue
dg.FooterStyle.BackColor = System.Drawing.Color.LightBlue
dg.AlternatingItemStyle.BackColor =
System.Drawing.Color.LightBlue
dg.SelectedItemStyle.BackColor =
System.Drawing.Color.LightGreen
dg.ShowHeader = False
dg.ShowFooter = False
dg.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
dg.Width = Unit.Percentage(20)

AddHandler dg.ItemDataBound, AddressOf OnItemDataBound
AddHandler dg.SelectedIndexChanged, AddressOf
OnSelectedIndexChanged

dg.DataBind()

Return dg
End Function

Private Overloads Sub OnSelectedIndexChanged(ByVal sender As
Object, _
ByVal e As System.EventArgs)
lblMessage.Text = "OnSelectedIndexChanged"
End Sub

Private Overloads Sub OnItemDataBound(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs)
Dim itemType As ListItemType = e.Item.ItemType
Dim container As DataGridItem
Dim colval As DictionaryEntry

If ((itemType <> ListItemType.Pager) And _
(itemType <> ListItemType.Header) And _
(itemType <> ListItemType.Footer)) Then
Dim lb As LinkButton = _
DirectCast(e.Item.FindControl("Select"), LinkButton)

e.Item.Attributes("onclick") = _
Page.GetPostBackClientHyperlink(lb, "")
End If
End Sub

Private Sub btnSubmit_Click(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles btnSubmit.Click
Me.ViewState("where") = "Tran_Date = '" + tbxDate.Text + "'"

BindData()
End Sub

Protected Overrides Sub LoadViewState(ByVal savedState As Object)
MyBase.LoadViewState(savedState)

If Page.IsPostBack Then
If Not IsNothing(Me.ViewState("where")) AndAlso _
Me.ViewState("where").ToString <> String.Empty Then
Dim where As String = Me.ViewState("where").ToString

BindData()
End If
End If
End Sub
End Class

================================================
================================================
 
A

Alvin Bruney [MVP]

You've created the grid but you haven't wired the event. At least, you
haven't said so. In your loadviewstate you should do
Datagrid.selectedindex += blah blah blah. that will hook it up
 
G

Glenn Owens

Alvin, thanks for your response. I'm not sure that I understand your
point.

In the LoadViewState method the Datagrid has not yet been created. In
fact, that's what I'm trying to accomplish in the method - to build
the DataGrid before the Load_Page event is fired (and the control
heirarchy is ready to be parsed). The whole point of my using the
LoadViewState is to restore the DataGrid so that, I assumed, the
EventHandlerList would have a control to reference when the changed
events are serviced (after the loading of the page).

One of the things I'm looking to discover in the SelectedIndexChanged
event is what index the Used has selected - that's what I need
SelectedIndexChanged event for (and it's arguments). So, I'd really
appreciate it if you'd elaborate a bit more on your thought of "wiring
up" the event in the LoadViewState method.

By-the-way, in debug-mode (in the Load_Page event handler), I do see
the Datagrid conrol fully attached to the NamingContainer (the aspx
page). So, I still don't understand why the SelectedIndexChanged event
of the dynamic DataGrid won't fire.

Glenn

Alvin Bruney said:
You've created the grid but you haven't wired the event. At least, you
haven't said so. In your loadviewstate you should do
Datagrid.selectedindex += blah blah blah. that will hook it up

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
Glenn Owens said:
OK, I'm stumped.

I've created a "simple" test web page (w/ code-behind) which does the
following:

Accepts a date criteria from the User (me) and has a asp:Button
"Submit"

On Submit the page creates, and adds, a dynamic DataGrid to the
control collection. The DataGrid has a "click-anywhere-on-a-row"
capability.

This all work well. The data is retrieved/displayed and, clicking a
DataGrid row, fires up the postback. The problem is that I had added
an event handler for the datagrid's SelectedIndexChanged event - which
doesn't fire.

I realize that I need to insure that the dynamic DataGrid is created
to support the SelectedIndexChanged event on Postback. To that end
I've saved the SQL SELECT statment (used to create/populate the
DataGrid in the ViewState. I've also overridden the LoadViewState
method (because it's before the Load_Page event) to call my "BindData"
method to create/bind the DataGrid.

Unfortunately, none of this results in the firing of the
SelectedIndexchanged event. I'm submitting the code with this post (in
hopes that it will clarify what I'm trying to do).

Please... I've taken these steps to try to solve the same issue in my
"real", time-critical app. Anyone who's got some experience with
Dynamic controls, the event model and the dreaded Postback please
HELP!!!

================================================
================================================
Public Class Test
Inherits AppBasePage

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub
Protected WithEvents tbxDate As System.Web.UI.WebControls.TextBox
Protected WithEvents lblDate As System.Web.UI.WebControls.Label
Protected WithEvents btnSubmit As System.Web.UI.WebControls.Button
Protected WithEvents lblMessage As System.Web.UI.WebControls.Label

'NOTE: The following placeholder declaration is required by the
Web Form Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form
Designer
'Do not modify it using the code editor.
InitializeComponent()

End Sub

#End Region

Private DisbTransDlo As DloDisbTrans

Private Sub Page_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load

If Not Page.IsPostBack Then
tbxDate.Text =
DateTime.Today.AddDays(-1).ToShortDateString
End If
End Sub

Private Sub BindData()
If DisbTransDlo Is Nothing Then
DisbTransDlo = New
DloDisbTrans(Me.GetConnection(Me._NPDISB))
End If

Me.Controls.Add(CreateDataGrid())
End Sub

Private Function CreateDataGrid() As MyDataGrid
Dim dg As New MyDataGrid

dg.AutoGenerateColumns = True
dg.DataSource = DisbTransDlo.RetrieveDataTable("sqlMonitor_0",
_
Me.ViewState("where").ToString)
dg.ID = "Testing"
dg.HeaderStyle.BackColor = System.Drawing.Color.LightBlue
dg.FooterStyle.BackColor = System.Drawing.Color.LightBlue
dg.AlternatingItemStyle.BackColor =
System.Drawing.Color.LightBlue
dg.SelectedItemStyle.BackColor =
System.Drawing.Color.LightGreen
dg.ShowHeader = False
dg.ShowFooter = False
dg.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
dg.Width = Unit.Percentage(20)

AddHandler dg.ItemDataBound, AddressOf OnItemDataBound
AddHandler dg.SelectedIndexChanged, AddressOf
OnSelectedIndexChanged

dg.DataBind()

Return dg
End Function

Private Overloads Sub OnSelectedIndexChanged(ByVal sender As
Object, _
ByVal e As System.EventArgs)
lblMessage.Text = "OnSelectedIndexChanged"
End Sub

Private Overloads Sub OnItemDataBound(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs)
Dim itemType As ListItemType = e.Item.ItemType
Dim container As DataGridItem
Dim colval As DictionaryEntry

If ((itemType <> ListItemType.Pager) And _
(itemType <> ListItemType.Header) And _
(itemType <> ListItemType.Footer)) Then
Dim lb As LinkButton = _
DirectCast(e.Item.FindControl("Select"), LinkButton)

e.Item.Attributes("onclick") = _
Page.GetPostBackClientHyperlink(lb, "")
End If
End Sub

Private Sub btnSubmit_Click(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles btnSubmit.Click
Me.ViewState("where") = "Tran_Date = '" + tbxDate.Text + "'"

BindData()
End Sub

Protected Overrides Sub LoadViewState(ByVal savedState As Object)
MyBase.LoadViewState(savedState)

If Page.IsPostBack Then
If Not IsNothing(Me.ViewState("where")) AndAlso _
Me.ViewState("where").ToString <> String.Empty Then
Dim where As String = Me.ViewState("where").ToString

BindData()
End If
End If
End Sub
End Class

================================================
================================================
Click to expand...
Click to expand...
 
A

Alvin Bruney [MVP]

well it is dynamic, which means by default, its events are not wired up. you
will have to wire them in whenever you create the datagrid otherwise the
dynamic datagrid will not be able to respond to any events. I make the
assumption that when you say the datagrid is dynamic you mean you are
creating it from code right? and not using the designer.

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
Glenn Owens said:
Alvin, thanks for your response. I'm not sure that I understand your
point.

In the LoadViewState method the Datagrid has not yet been created. In
fact, that's what I'm trying to accomplish in the method - to build
the DataGrid before the Load_Page event is fired (and the control
heirarchy is ready to be parsed). The whole point of my using the
LoadViewState is to restore the DataGrid so that, I assumed, the
EventHandlerList would have a control to reference when the changed
events are serviced (after the loading of the page).

One of the things I'm looking to discover in the SelectedIndexChanged
event is what index the Used has selected - that's what I need
SelectedIndexChanged event for (and it's arguments). So, I'd really
appreciate it if you'd elaborate a bit more on your thought of "wiring
up" the event in the LoadViewState method.

By-the-way, in debug-mode (in the Load_Page event handler), I do see
the Datagrid conrol fully attached to the NamingContainer (the aspx
page). So, I still don't understand why the SelectedIndexChanged event
of the dynamic DataGrid won't fire.

Glenn

Alvin Bruney said:
You've created the grid but you haven't wired the event. At least, you
haven't said so. In your loadviewstate you should do
Datagrid.selectedindex += blah blah blah. that will hook it up

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
Glenn Owens said:
OK, I'm stumped.

I've created a "simple" test web page (w/ code-behind) which does the
following:

Accepts a date criteria from the User (me) and has a asp:Button
"Submit"

On Submit the page creates, and adds, a dynamic DataGrid to the
control collection. The DataGrid has a "click-anywhere-on-a-row"
capability.

This all work well. The data is retrieved/displayed and, clicking a
DataGrid row, fires up the postback. The problem is that I had added
an event handler for the datagrid's SelectedIndexChanged event - which
doesn't fire.

I realize that I need to insure that the dynamic DataGrid is created
to support the SelectedIndexChanged event on Postback. To that end
I've saved the SQL SELECT statment (used to create/populate the
DataGrid in the ViewState. I've also overridden the LoadViewState
method (because it's before the Load_Page event) to call my "BindData"
method to create/bind the DataGrid.

Unfortunately, none of this results in the firing of the
SelectedIndexchanged event. I'm submitting the code with this post (in
hopes that it will clarify what I'm trying to do).

Please... I've taken these steps to try to solve the same issue in my
"real", time-critical app. Anyone who's got some experience with
Dynamic controls, the event model and the dreaded Postback please
HELP!!!

================================================
================================================
Public Class Test
Inherits AppBasePage

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub
Protected WithEvents tbxDate As System.Web.UI.WebControls.TextBox
Protected WithEvents lblDate As System.Web.UI.WebControls.Label
Protected WithEvents btnSubmit As System.Web.UI.WebControls.Button
Protected WithEvents lblMessage As System.Web.UI.WebControls.Label

'NOTE: The following placeholder declaration is required by the
Web Form Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form
Designer
'Do not modify it using the code editor.
InitializeComponent()

End Sub

#End Region

Private DisbTransDlo As DloDisbTrans

Private Sub Page_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load

If Not Page.IsPostBack Then
tbxDate.Text =
DateTime.Today.AddDays(-1).ToShortDateString
End If
End Sub

Private Sub BindData()
If DisbTransDlo Is Nothing Then
DisbTransDlo = New
DloDisbTrans(Me.GetConnection(Me._NPDISB))
End If

Me.Controls.Add(CreateDataGrid())
End Sub

Private Function CreateDataGrid() As MyDataGrid
Dim dg As New MyDataGrid

dg.AutoGenerateColumns = True
dg.DataSource = DisbTransDlo.RetrieveDataTable("sqlMonitor_0",
_
Me.ViewState("where").ToString)
dg.ID = "Testing"
dg.HeaderStyle.BackColor = System.Drawing.Color.LightBlue
dg.FooterStyle.BackColor = System.Drawing.Color.LightBlue
dg.AlternatingItemStyle.BackColor =
System.Drawing.Color.LightBlue
dg.SelectedItemStyle.BackColor =
System.Drawing.Color.LightGreen
dg.ShowHeader = False
dg.ShowFooter = False
dg.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
dg.Width = Unit.Percentage(20)

AddHandler dg.ItemDataBound, AddressOf OnItemDataBound
AddHandler dg.SelectedIndexChanged, AddressOf
OnSelectedIndexChanged

dg.DataBind()

Return dg
End Function

Private Overloads Sub OnSelectedIndexChanged(ByVal sender As
Object, _
ByVal e As System.EventArgs)
lblMessage.Text = "OnSelectedIndexChanged"
End Sub

Private Overloads Sub OnItemDataBound(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs)
Dim itemType As ListItemType = e.Item.ItemType
Dim container As DataGridItem
Dim colval As DictionaryEntry

If ((itemType <> ListItemType.Pager) And _
(itemType <> ListItemType.Header) And _
(itemType <> ListItemType.Footer)) Then
Dim lb As LinkButton = _
DirectCast(e.Item.FindControl("Select"), LinkButton)

e.Item.Attributes("onclick") = _
Page.GetPostBackClientHyperlink(lb, "")
End If
End Sub

Private Sub btnSubmit_Click(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles btnSubmit.Click
Me.ViewState("where") = "Tran_Date = '" + tbxDate.Text + "'"

BindData()
End Sub

Protected Overrides Sub LoadViewState(ByVal savedState As Object)
MyBase.LoadViewState(savedState)

If Page.IsPostBack Then
If Not IsNothing(Me.ViewState("where")) AndAlso _
Me.ViewState("where").ToString <> String.Empty Then
Dim where As String = Me.ViewState("where").ToString

BindData()
End If
End If
End Sub
End Class

================================================
================================================
Click to expand...
Click to expand...
Click to expand...
 
G

Glenn Owens

Yup, I'm creating the Datagrid from code. So, not knowing what row the
User has clicked, how should I "wire up" the SelectedIndexchange
event? I've got to believe that this is something that a lot of
developers could use but I've had a difficult time finding the
answers.

Thanks for taking the time to help!
Glenn

Alvin Bruney said:
well it is dynamic, which means by default, its events are not wired up. you
will have to wire them in whenever you create the datagrid otherwise the
dynamic datagrid will not be able to respond to any events. I make the
assumption that when you say the datagrid is dynamic you mean you are
creating it from code right? and not using the designer.

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
Glenn Owens said:
Alvin, thanks for your response. I'm not sure that I understand your
point.

In the LoadViewState method the Datagrid has not yet been created. In
fact, that's what I'm trying to accomplish in the method - to build
the DataGrid before the Load_Page event is fired (and the control
heirarchy is ready to be parsed). The whole point of my using the
LoadViewState is to restore the DataGrid so that, I assumed, the
EventHandlerList would have a control to reference when the changed
events are serviced (after the loading of the page).

One of the things I'm looking to discover in the SelectedIndexChanged
event is what index the Used has selected - that's what I need
SelectedIndexChanged event for (and it's arguments). So, I'd really
appreciate it if you'd elaborate a bit more on your thought of "wiring
up" the event in the LoadViewState method.

By-the-way, in debug-mode (in the Load_Page event handler), I do see
the Datagrid conrol fully attached to the NamingContainer (the aspx
page). So, I still don't understand why the SelectedIndexChanged event
of the dynamic DataGrid won't fire.

Glenn

Alvin Bruney said:
You've created the grid but you haven't wired the event. At least, you
haven't said so. In your loadviewstate you should do
Datagrid.selectedindex += blah blah blah. that will hook it up

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
OK, I'm stumped.

I've created a "simple" test web page (w/ code-behind) which does the
following:

Accepts a date criteria from the User (me) and has a asp:Button
"Submit"

On Submit the page creates, and adds, a dynamic DataGrid to the
control collection. The DataGrid has a "click-anywhere-on-a-row"
capability.

This all work well. The data is retrieved/displayed and, clicking a
DataGrid row, fires up the postback. The problem is that I had added
an event handler for the datagrid's SelectedIndexChanged event - which
doesn't fire.

I realize that I need to insure that the dynamic DataGrid is created
to support the SelectedIndexChanged event on Postback. To that end
I've saved the SQL SELECT statment (used to create/populate the
DataGrid in the ViewState. I've also overridden the LoadViewState
method (because it's before the Load_Page event) to call my "BindData"
method to create/bind the DataGrid.

Unfortunately, none of this results in the firing of the
SelectedIndexchanged event. I'm submitting the code with this post (in
hopes that it will clarify what I'm trying to do).

Please... I've taken these steps to try to solve the same issue in my
"real", time-critical app. Anyone who's got some experience with
Dynamic controls, the event model and the dreaded Postback please
HELP!!!

================================================
================================================
Public Class Test
Inherits AppBasePage

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub
Protected WithEvents tbxDate As System.Web.UI.WebControls.TextBox
Protected WithEvents lblDate As System.Web.UI.WebControls.Label
Protected WithEvents btnSubmit As System.Web.UI.WebControls.Button
Protected WithEvents lblMessage As System.Web.UI.WebControls.Label

'NOTE: The following placeholder declaration is required by the
Web Form Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form
Designer
'Do not modify it using the code editor.
InitializeComponent()

End Sub

#End Region

Private DisbTransDlo As DloDisbTrans

Private Sub Page_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load

If Not Page.IsPostBack Then
tbxDate.Text =
DateTime.Today.AddDays(-1).ToShortDateString
End If
End Sub

Private Sub BindData()
If DisbTransDlo Is Nothing Then
DisbTransDlo = New
DloDisbTrans(Me.GetConnection(Me._NPDISB))
End If

Me.Controls.Add(CreateDataGrid())
End Sub

Private Function CreateDataGrid() As MyDataGrid
Dim dg As New MyDataGrid

dg.AutoGenerateColumns = True
dg.DataSource = DisbTransDlo.RetrieveDataTable("sqlMonitor_0",
_
Me.ViewState("where").ToString)
dg.ID = "Testing"
dg.HeaderStyle.BackColor = System.Drawing.Color.LightBlue
dg.FooterStyle.BackColor = System.Drawing.Color.LightBlue
dg.AlternatingItemStyle.BackColor =
System.Drawing.Color.LightBlue
dg.SelectedItemStyle.BackColor =
System.Drawing.Color.LightGreen
dg.ShowHeader = False
dg.ShowFooter = False
dg.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
dg.Width = Unit.Percentage(20)

AddHandler dg.ItemDataBound, AddressOf OnItemDataBound
AddHandler dg.SelectedIndexChanged, AddressOf
OnSelectedIndexChanged

dg.DataBind()

Return dg
End Function

Private Overloads Sub OnSelectedIndexChanged(ByVal sender As
Object, _
ByVal e As System.EventArgs)
lblMessage.Text = "OnSelectedIndexChanged"
End Sub

Private Overloads Sub OnItemDataBound(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs)
Dim itemType As ListItemType = e.Item.ItemType
Dim container As DataGridItem
Dim colval As DictionaryEntry

If ((itemType <> ListItemType.Pager) And _
(itemType <> ListItemType.Header) And _
(itemType <> ListItemType.Footer)) Then
Dim lb As LinkButton = _
DirectCast(e.Item.FindControl("Select"), LinkButton)

e.Item.Attributes("onclick") = _
Page.GetPostBackClientHyperlink(lb, "")
End If
End Sub

Private Sub btnSubmit_Click(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles btnSubmit.Click
Me.ViewState("where") = "Tran_Date = '" + tbxDate.Text + "'"

BindData()
End Sub

Protected Overrides Sub LoadViewState(ByVal savedState As Object)
MyBase.LoadViewState(savedState)

If Page.IsPostBack Then
If Not IsNothing(Me.ViewState("where")) AndAlso _
Me.ViewState("where").ToString <> String.Empty Then
Dim where As String = Me.ViewState("where").ToString

BindData()
End If
End If
End Sub
End Class

================================================
================================================
Click to expand...
Click to expand...
Click to expand...
 
G

Glenn Owens

Well... I found the problem (how embarassing). One thing that I had
done (before using the LoadViewState method to re-create the Datagrid
control) was to override the OnSelectedIndexChanged event handler in
my DataGrid control (just to see if, in debug, the event was firing).

After implementing the code in the LoadViewState (which did
successfuly create the DataGrid and wire the events) everything was
working correctly! However, because I never put any code into the
override OnSelectedInddexChanged (in my DataGrid control) the event
never bubbled up to the page event handler.

What I needed to do was: 1) lose the OnSelectedIndexChanged handler
all-together (which I did) -or- 2) include the
mybase.OnselectedIndexChanged in the DataGrid handler (which does
cause the event to bubble-up.

====================================
====================================

Alvin, thank you for your responses and time. One thing about .Net is
that you're never at a loss for new things to learn! I do hope that
these discussions is helpful to others down the road...

Glenn



Yup, I'm creating the Datagrid from code. So, not knowing what row the
User has clicked, how should I "wire up" the SelectedIndexchange
event? I've got to believe that this is something that a lot of
developers could use but I've had a difficult time finding the
answers.

Thanks for taking the time to help!
Glenn

Alvin Bruney said:
well it is dynamic, which means by default, its events are not wired up. you
will have to wire them in whenever you create the datagrid otherwise the
dynamic datagrid will not be able to respond to any events. I make the
assumption that when you say the datagrid is dynamic you mean you are
creating it from code right? and not using the designer.

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
Glenn Owens said:
Alvin, thanks for your response. I'm not sure that I understand your
point.

In the LoadViewState method the Datagrid has not yet been created. In
fact, that's what I'm trying to accomplish in the method - to build
the DataGrid before the Load_Page event is fired (and the control
heirarchy is ready to be parsed). The whole point of my using the
LoadViewState is to restore the DataGrid so that, I assumed, the
EventHandlerList would have a control to reference when the changed
events are serviced (after the loading of the page).

One of the things I'm looking to discover in the SelectedIndexChanged
event is what index the Used has selected - that's what I need
SelectedIndexChanged event for (and it's arguments). So, I'd really
appreciate it if you'd elaborate a bit more on your thought of "wiring
up" the event in the LoadViewState method.

By-the-way, in debug-mode (in the Load_Page event handler), I do see
the Datagrid conrol fully attached to the NamingContainer (the aspx
page). So, I still don't understand why the SelectedIndexChanged event
of the dynamic DataGrid won't fire.

Glenn

"Alvin Bruney [MVP]" <vapor at steaming post office> wrote in message
You've created the grid but you haven't wired the event. At least, you
haven't said so. In your loadviewstate you should do
Datagrid.selectedindex += blah blah blah. that will hook it up

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
OK, I'm stumped.

I've created a "simple" test web page (w/ code-behind) which does the
following:

Accepts a date criteria from the User (me) and has a asp:Button
"Submit"

On Submit the page creates, and adds, a dynamic DataGrid to the
control collection. The DataGrid has a "click-anywhere-on-a-row"
capability.

This all work well. The data is retrieved/displayed and, clicking a
DataGrid row, fires up the postback. The problem is that I had added
an event handler for the datagrid's SelectedIndexChanged event - which
doesn't fire.

I realize that I need to insure that the dynamic DataGrid is created
to support the SelectedIndexChanged event on Postback. To that end
I've saved the SQL SELECT statment (used to create/populate the
DataGrid in the ViewState. I've also overridden the LoadViewState
method (because it's before the Load_Page event) to call my "BindData"
method to create/bind the DataGrid.

Unfortunately, none of this results in the firing of the
SelectedIndexchanged event. I'm submitting the code with this post (in
hopes that it will clarify what I'm trying to do).

Please... I've taken these steps to try to solve the same issue in my
"real", time-critical app. Anyone who's got some experience with
Dynamic controls, the event model and the dreaded Postback please
HELP!!!

================================================
================================================
Public Class Test
Inherits AppBasePage

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub
Protected WithEvents tbxDate As System.Web.UI.WebControls.TextBox
Protected WithEvents lblDate As System.Web.UI.WebControls.Label
Protected WithEvents btnSubmit As System.Web.UI.WebControls.Button
Protected WithEvents lblMessage As System.Web.UI.WebControls.Label

'NOTE: The following placeholder declaration is required by the
Web Form Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form
Designer
'Do not modify it using the code editor.
InitializeComponent()

End Sub

#End Region

Private DisbTransDlo As DloDisbTrans

Private Sub Page_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load

If Not Page.IsPostBack Then
tbxDate.Text =
DateTime.Today.AddDays(-1).ToShortDateString
End If
End Sub

Private Sub BindData()
If DisbTransDlo Is Nothing Then
DisbTransDlo = New
DloDisbTrans(Me.GetConnection(Me._NPDISB))
End If

Me.Controls.Add(CreateDataGrid())
End Sub

Private Function CreateDataGrid() As MyDataGrid
Dim dg As New MyDataGrid

dg.AutoGenerateColumns = True
dg.DataSource = DisbTransDlo.RetrieveDataTable("sqlMonitor_0",
_
Me.ViewState("where").ToString)
dg.ID = "Testing"
dg.HeaderStyle.BackColor = System.Drawing.Color.LightBlue
dg.FooterStyle.BackColor = System.Drawing.Color.LightBlue
dg.AlternatingItemStyle.BackColor =
System.Drawing.Color.LightBlue
dg.SelectedItemStyle.BackColor =
System.Drawing.Color.LightGreen
dg.ShowHeader = False
dg.ShowFooter = False
dg.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
dg.Width = Unit.Percentage(20)

AddHandler dg.ItemDataBound, AddressOf OnItemDataBound
AddHandler dg.SelectedIndexChanged, AddressOf
OnSelectedIndexChanged

dg.DataBind()

Return dg
End Function

Private Overloads Sub OnSelectedIndexChanged(ByVal sender As
Object, _
ByVal e As System.EventArgs)
lblMessage.Text = "OnSelectedIndexChanged"
End Sub

Private Overloads Sub OnItemDataBound(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs)
Dim itemType As ListItemType = e.Item.ItemType
Dim container As DataGridItem
Dim colval As DictionaryEntry

If ((itemType <> ListItemType.Pager) And _
(itemType <> ListItemType.Header) And _
(itemType <> ListItemType.Footer)) Then
Dim lb As LinkButton = _
DirectCast(e.Item.FindControl("Select"), LinkButton)

e.Item.Attributes("onclick") = _
Page.GetPostBackClientHyperlink(lb, "")
End If
End Sub

Private Sub btnSubmit_Click(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles btnSubmit.Click
Me.ViewState("where") = "Tran_Date = '" + tbxDate.Text + "'"

BindData()
End Sub

Protected Overrides Sub LoadViewState(ByVal savedState As Object)
MyBase.LoadViewState(savedState)

If Page.IsPostBack Then
If Not IsNothing(Me.ViewState("where")) AndAlso _
Me.ViewState("where").ToString <> String.Empty Then
Dim where As String = Me.ViewState("where").ToString

BindData()
End If
End If
End Sub
End Class

================================================
================================================
Click to expand...
Click to expand...
Click to expand...
 
A

Alvin Bruney [MVP]

glad you figured it out

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
Glenn Owens said:
Well... I found the problem (how embarassing). One thing that I had
done (before using the LoadViewState method to re-create the Datagrid
control) was to override the OnSelectedIndexChanged event handler in
my DataGrid control (just to see if, in debug, the event was firing).

After implementing the code in the LoadViewState (which did
successfuly create the DataGrid and wire the events) everything was
working correctly! However, because I never put any code into the
override OnSelectedInddexChanged (in my DataGrid control) the event
never bubbled up to the page event handler.

What I needed to do was: 1) lose the OnSelectedIndexChanged handler
all-together (which I did) -or- 2) include the
mybase.OnselectedIndexChanged in the DataGrid handler (which does
cause the event to bubble-up.

====================================
====================================

Alvin, thank you for your responses and time. One thing about .Net is
that you're never at a loss for new things to learn! I do hope that
these discussions is helpful to others down the road...

Glenn



(e-mail address removed) (Glenn Owens) wrote in message
Yup, I'm creating the Datagrid from code. So, not knowing what row the
User has clicked, how should I "wire up" the SelectedIndexchange
event? I've got to believe that this is something that a lot of
developers could use but I've had a difficult time finding the
answers.

Thanks for taking the time to help!
Glenn

Alvin Bruney said:
well it is dynamic, which means by default, its events are not wired
up. you
will have to wire them in whenever you create the datagrid otherwise
the
dynamic datagrid will not be able to respond to any events. I make the
assumption that when you say the datagrid is dynamic you mean you are
creating it from code right? and not using the designer.

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
Alvin, thanks for your response. I'm not sure that I understand your
point.

In the LoadViewState method the Datagrid has not yet been created. In
fact, that's what I'm trying to accomplish in the method - to build
the DataGrid before the Load_Page event is fired (and the control
heirarchy is ready to be parsed). The whole point of my using the
LoadViewState is to restore the DataGrid so that, I assumed, the
EventHandlerList would have a control to reference when the changed
events are serviced (after the loading of the page).

One of the things I'm looking to discover in the SelectedIndexChanged
event is what index the Used has selected - that's what I need
SelectedIndexChanged event for (and it's arguments). So, I'd really
appreciate it if you'd elaborate a bit more on your thought of
"wiring
up" the event in the LoadViewState method.

By-the-way, in debug-mode (in the Load_Page event handler), I do see
the Datagrid conrol fully attached to the NamingContainer (the aspx
page). So, I still don't understand why the SelectedIndexChanged
event
of the dynamic DataGrid won't fire.

Glenn

"Alvin Bruney [MVP]" <vapor at steaming post office> wrote in message
You've created the grid but you haven't wired the event. At least,
you
haven't said so. In your loadviewstate you should do
Datagrid.selectedindex += blah blah blah. that will hook it up

--
Regards,
Alvin Bruney
[ASP.NET MVP http://mvp.support.microsoft.com/default.aspx]
Got tidbits? Get it here... http://tinyurl.com/27cok
OK, I'm stumped.

I've created a "simple" test web page (w/ code-behind) which does
the
following:

Accepts a date criteria from the User (me) and has a asp:Button
"Submit"

On Submit the page creates, and adds, a dynamic DataGrid to the
control collection. The DataGrid has a "click-anywhere-on-a-row"
capability.

This all work well. The data is retrieved/displayed and, clicking
a
DataGrid row, fires up the postback. The problem is that I had
added
an event handler for the datagrid's SelectedIndexChanged event -
which
doesn't fire.

I realize that I need to insure that the dynamic DataGrid is
created
to support the SelectedIndexChanged event on Postback. To that end
I've saved the SQL SELECT statment (used to create/populate the
DataGrid in the ViewState. I've also overridden the LoadViewState
method (because it's before the Load_Page event) to call my
"BindData"
method to create/bind the DataGrid.

Unfortunately, none of this results in the firing of the
SelectedIndexchanged event. I'm submitting the code with this post
(in
hopes that it will clarify what I'm trying to do).

Please... I've taken these steps to try to solve the same issue in
my
"real", time-critical app. Anyone who's got some experience with
Dynamic controls, the event model and the dreaded Postback please
HELP!!!

================================================
================================================
Public Class Test
Inherits AppBasePage

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub
Protected WithEvents tbxDate As
System.Web.UI.WebControls.TextBox
Protected WithEvents lblDate As System.Web.UI.WebControls.Label
Protected WithEvents btnSubmit As
System.Web.UI.WebControls.Button
Protected WithEvents lblMessage As
System.Web.UI.WebControls.Label

'NOTE: The following placeholder declaration is required by the
Web Form Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form
Designer
'Do not modify it using the code editor.
InitializeComponent()

End Sub

#End Region

Private DisbTransDlo As DloDisbTrans

Private Sub Page_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load

If Not Page.IsPostBack Then
tbxDate.Text =
DateTime.Today.AddDays(-1).ToShortDateString
End If
End Sub

Private Sub BindData()
If DisbTransDlo Is Nothing Then
DisbTransDlo = New
DloDisbTrans(Me.GetConnection(Me._NPDISB))
End If

Me.Controls.Add(CreateDataGrid())
End Sub

Private Function CreateDataGrid() As MyDataGrid
Dim dg As New MyDataGrid

dg.AutoGenerateColumns = True
dg.DataSource =
DisbTransDlo.RetrieveDataTable("sqlMonitor_0",
_
Me.ViewState("where").ToString)
dg.ID = "Testing"
dg.HeaderStyle.BackColor = System.Drawing.Color.LightBlue
dg.FooterStyle.BackColor = System.Drawing.Color.LightBlue
dg.AlternatingItemStyle.BackColor =
System.Drawing.Color.LightBlue
dg.SelectedItemStyle.BackColor =
System.Drawing.Color.LightGreen
dg.ShowHeader = False
dg.ShowFooter = False
dg.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
dg.Width = Unit.Percentage(20)

AddHandler dg.ItemDataBound, AddressOf OnItemDataBound
AddHandler dg.SelectedIndexChanged, AddressOf
OnSelectedIndexChanged

dg.DataBind()

Return dg
End Function

Private Overloads Sub OnSelectedIndexChanged(ByVal sender As
Object, _
ByVal e As System.EventArgs)
lblMessage.Text = "OnSelectedIndexChanged"
End Sub

Private Overloads Sub OnItemDataBound(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs)
Dim itemType As ListItemType = e.Item.ItemType
Dim container As DataGridItem
Dim colval As DictionaryEntry

If ((itemType <> ListItemType.Pager) And _
(itemType <> ListItemType.Header) And _
(itemType <> ListItemType.Footer)) Then
Dim lb As LinkButton = _
DirectCast(e.Item.FindControl("Select"),
LinkButton)

e.Item.Attributes("onclick") = _
Page.GetPostBackClientHyperlink(lb, "")
End If
End Sub

Private Sub btnSubmit_Click(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles btnSubmit.Click
Me.ViewState("where") = "Tran_Date = '" + tbxDate.Text +
"'"

BindData()
End Sub

Protected Overrides Sub LoadViewState(ByVal savedState As
Object)
MyBase.LoadViewState(savedState)

If Page.IsPostBack Then
If Not IsNothing(Me.ViewState("where")) AndAlso _
Me.ViewState("where").ToString <> String.Empty Then
Dim where As String =
Me.ViewState("where").ToString

BindData()
End If
End If
End Sub
End Class

================================================
================================================
Click to expand...
Click to expand...
Click to expand...
 

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question

Similar Threads

__postback datagrid 0
Slow datagrid on postback 1
Invisible folder 0
AutoGenerateColumns - DataGrid Paging 3
Create DataGrid at runtime 1
Sort not firing PostBack event using Dynamic Columns 2
Custom Datagrid disappearing on Postback 5
creating instance of an inner nested datagrid 0

Members online

Total: 73 (members: 2, guests: 71)
Robots: 499

Forum statistics

Threads
473,992
Messages
2,570,220
Members
46,807
Latest member
ryef

Latest Threads

Top