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aspx thread: Making a Button control visible/hidden within a Datagrid?

Message #1 by "Oliver, Wells" <WOliver@l...> on Wed, 17 Jul 2002 08:38:46 -0700

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I have a datagrid displaying some data (bulletin board posts). Within each
row, I have a button which allows editing of that data.

However, I want only the users who made the post to have the button
displayed on that row. The user's name is in the session and is also a
column in the datagrid, so I can match the two strings to determine whether
or not to display the Edit button for that row.

Any ideas? Thanks.

Wells Oliver
Web Application Programmer
Leviton Voice & Data
xxx-xxx-xxxx
http://www.levitonvoicedata.com

Message #2 by Feduke Cntr Charles R <FedukeCR@m...> on Wed, 17 Jul 2002 12:00:02 -0400

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Wells,
 
    The easiest (nasty) way to do this is to add a <% %> block in your
ItemTemplate to do a test:
 
<% If (SomeCondition) %>
    <asp:Button RunAt="server" />
<% End If %>
 
    Of course if you want to distance yourself from crappy ASP stuff, then
you'll want to not have any blocks of <% %> in your *.aspx files at all.  To
do this, you'll need to hook the ItemCreated event of the DataGrid, and
using the arguments passed to the event (the event fires every time a new
row is added to the data grid, among other things) you can test and see if a
condition is met for the current row to show or hide the <asp:Button> you
have in your <ItemTemplate>.
 
HTH,
 
- Chuck

-----Original Message-----
From: Oliver, Wells [mailto:WOliver@l...]
Sent: Wednesday, July 17, 2002 11:39 AM
To: ASP+
Subject: [aspx] Making a Button control visible/hidden within a Datagrid?



I have a datagrid displaying some data (bulletin board posts). Within each
row, I have a button which allows editing of that data.

However, I want only the users who made the post to have the button
displayed on that row. The user's name is in the session and is also a
column in the datagrid, so I can match the two strings to determine whether
or not to display the Edit button for that row.

Any ideas? Thanks. 

Wells Oliver 
Web Application Programmer 
Leviton Voice & Data 
xxx-xxx-xxxx 
http://www.levitonvoicedata.com <http://www.levitonvoicedata.com>  

--- Change your mail options at http://p2p.wrox.com/manager.asp or to
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Message #3 by "Oliver, Wells" <WOliver@l...> on Wed, 17 Jul 2002 15:06:25 -0700

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this format, some or all of this message may not be legible.

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Excellent idea.. One question. I've written this subroutine:
 
Public Sub ShowButton (S as System.Object, E as DataListItemEventArgs)

E.Item.FindControl ("editButton").Visible = False

End Sub

It's not exactly working-- I have a Button control with the id of
"editButton" w/in the DataList. How can I edit the properties of that button
from w/in that subroutine?

-----Original Message-----
From: Feduke Cntr Charles R [mailto:FedukeCR@m...]
Sent: Wednesday, July 17, 2002 9:00 AM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Datagr
id?


Wells,
 
    The easiest (nasty) way to do this is to add a <% %> block in your
ItemTemplate to do a test:
 
<% If (SomeCondition) %>
    <asp:Button RunAt="server" />
<% End If %>
 
    Of course if you want to distance yourself from crappy ASP stuff, then
you'll want to not have any blocks of <% %> in your *.aspx files at all.  To
do this, you'll need to hook the ItemCreated event of the DataGrid, and
using the arguments passed to the event (the event fires every time a new
row is added to the data grid, among other things) you can test and see if a
condition is met for the current row to show or hide the <asp:Button> you
have in your <ItemTemplate>.
 
HTH,
 
- Chuck

-----Original Message-----
From: Oliver, Wells [mailto:WOliver@l...]
Sent: Wednesday, July 17, 2002 11:39 AM
To: ASP+
Subject: [aspx] Making a Button control visible/hidden within a Datagrid?



I have a datagrid displaying some data (bulletin board posts). Within each
row, I have a button which allows editing of that data.

However, I want only the users who made the post to have the button
displayed on that row. The user's name is in the session and is also a
column in the datagrid, so I can match the two strings to determine whether
or not to display the Edit button for that row.

Any ideas? Thanks. 

Wells Oliver 
Web Application Programmer 
Leviton Voice & Data 
xxx-xxx-xxxx 
http://www.levitonvoicedata.com <http://www.levitonvoicedata.com>  

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Message #4 by Feduke Cntr Charles R <FedukeCR@m...> on Thu, 18 Jul 2002 09:25:34 -0400

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Is it throwing an error on your .Visible line, or is it just not causing
anything visual to happen?
 
- Chuck

-----Original Message-----
From: Oliver, Wells [mailto:WOliver@l...]
Sent: Wednesday, July 17, 2002 6:06 PM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Da tagr
id?


Excellent idea.. One question. I've written this subroutine:
 
Public Sub ShowButton (S as System.Object, E as DataListItemEventArgs)

E.Item.FindControl ("editButton").Visible = False

End Sub

It's not exactly working-- I have a Button control with the id of
"editButton" w/in the DataList. How can I edit the properties of that button
from w/in that subroutine?

-----Original Message-----
From: Feduke Cntr Charles R [mailto:FedukeCR@m...]
Sent: Wednesday, July 17, 2002 9:00 AM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Datagr
id?


Wells,
 
    The easiest (nasty) way to do this is to add a <% %> block in your
ItemTemplate to do a test:
 
<% If (SomeCondition) %>
    <asp:Button RunAt="server" />
<% End If %>
 
    Of course if you want to distance yourself from crappy ASP stuff, then
you'll want to not have any blocks of <% %> in your *.aspx files at all.  To
do this, you'll need to hook the ItemCreated event of the DataGrid, and
using the arguments passed to the event (the event fires every time a new
row is added to the data grid, among other things) you can test and see if a
condition is met for the current row to show or hide the <asp:Button> you
have in your <ItemTemplate>.
 
HTH,
 
- Chuck

-----Original Message-----
From: Oliver, Wells [mailto:WOliver@l...]
Sent: Wednesday, July 17, 2002 11:39 AM
To: ASP+
Subject: [aspx] Making a Button control visible/hidden within a Datagrid?



I have a datagrid displaying some data (bulletin board posts). Within each
row, I have a button which allows editing of that data.

However, I want only the users who made the post to have the button
displayed on that row. The user's name is in the session and is also a
column in the datagrid, so I can match the two strings to determine whether
or not to display the Edit button for that row.

Any ideas? Thanks. 

Wells Oliver 
Web Application Programmer 
Leviton Voice & Data 
xxx-xxx-xxxx 
http://www.levitonvoicedata.com <http://www.levitonvoicedata.com>  

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Message #5 by "Oliver, Wells" <WOliver@l...> on Thu, 18 Jul 2002 08:12:27 -0700

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Yeah, I get an error:
Exception Details: System.NullReferenceException: Object reference not set
to an instance of an object.

I'm assuming this should be easy, but I'm just not sure where to go. Turning
off a button with the id of "editButton" when the ITemCreated event is
fired..

-----Original Message-----
From: Feduke Cntr Charles R [mailto:FedukeCR@m...]
Sent: Thursday, July 18, 2002 6:26 AM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Da tagr
id?


Is it throwing an error on your .Visible line, or is it just not causing
anything visual to happen?
 
- Chuck

-----Original Message-----
From: Oliver, Wells [mailto:WOliver@l...]
Sent: Wednesday, July 17, 2002 6:06 PM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Da tagr
id?


Excellent idea.. One question. I've written this subroutine:
 
Public Sub ShowButton (S as System.Object, E as DataListItemEventArgs)

E.Item.FindControl ("editButton").Visible = False

End Sub

It's not exactly working-- I have a Button control with the id of
"editButton" w/in the DataList. How can I edit the properties of that button
from w/in that subroutine?

-----Original Message-----
From: Feduke Cntr Charles R [mailto:FedukeCR@m...]
Sent: Wednesday, July 17, 2002 9:00 AM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Datagr
id?


Wells,
 
    The easiest (nasty) way to do this is to add a <% %> block in your
ItemTemplate to do a test:
 
<% If (SomeCondition) %>
    <asp:Button RunAt="server" />
<% End If %>
 
    Of course if you want to distance yourself from crappy ASP stuff, then
you'll want to not have any blocks of <% %> in your *.aspx files at all.  To
do this, you'll need to hook the ItemCreated event of the DataGrid, and
using the arguments passed to the event (the event fires every time a new
row is added to the data grid, among other things) you can test and see if a
condition is met for the current row to show or hide the <asp:Button> you
have in your <ItemTemplate>.
 
HTH,
 
- Chuck

-----Original Message-----
From: Oliver, Wells [mailto:WOliver@l...]
Sent: Wednesday, July 17, 2002 11:39 AM
To: ASP+
Subject: [aspx] Making a Button control visible/hidden within a Datagrid?



I have a datagrid displaying some data (bulletin board posts). Within each
row, I have a button which allows editing of that data.

However, I want only the users who made the post to have the button
displayed on that row. The user's name is in the session and is also a
column in the datagrid, so I can match the two strings to determine whether
or not to display the Edit button for that row.

Any ideas? Thanks. 

Wells Oliver 
Web Application Programmer 
Leviton Voice & Data 
xxx-xxx-xxxx 
http://www.levitonvoicedata.com <http://www.levitonvoicedata.com>  

--- Change your mail options at http://p2p.wrox.com/manager.asp or to
unsubscribe send a blank email to  

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Message #6 by Feduke Cntr Charles R <FedukeCR@m...> on Thu, 18 Jul 2002 11:36:35 -0400

This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.

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Try putting it in an If... Then block:
 
If e.Item.FindControl("editButton") Is Not Nothing Then ' is that how you do
!= null in VB?
    e.Item.FindControl("editButton").Visible = False
End If
 
Of course keep in mind that FindControl is going to cost you a performance
hit if you you're using it for EVERY item created.  Take a look at the
DataGridEventArgs and first check and see what item type the e variable is
before trying to FindControl (i.e. if its header or footer then you don't
need to check).
 
- Chuck

-----Original Message-----
From: Oliver, Wells [mailto:WOliver@l...]
Sent: Thursday, July 18, 2002 11:12 AM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Da tagr
id?


Yeah, I get an error:
Exception Details: System.NullReferenceException: Object reference not set
to an instance of an object.

I'm assuming this should be easy, but I'm just not sure where to go. Turning
off a button with the id of "editButton" when the ITemCreated event is
fired..

-----Original Message-----
From: Feduke Cntr Charles R [mailto:FedukeCR@m...]
Sent: Thursday, July 18, 2002 6:26 AM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Da tagr
id?


Is it throwing an error on your .Visible line, or is it just not causing
anything visual to happen?
 
- Chuck

-----Original Message-----
From: Oliver, Wells [mailto:WOliver@l...]
Sent: Wednesday, July 17, 2002 6:06 PM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Da tagr
id?


Excellent idea.. One question. I've written this subroutine:
 
Public Sub ShowButton (S as System.Object, E as DataListItemEventArgs)

E.Item.FindControl ("editButton").Visible = False

End Sub

It's not exactly working-- I have a Button control with the id of
"editButton" w/in the DataList. How can I edit the properties of that button
from w/in that subroutine?

-----Original Message-----
From: Feduke Cntr Charles R [mailto:FedukeCR@m...]
Sent: Wednesday, July 17, 2002 9:00 AM
To: ASP+
Subject: [aspx] RE: Making a Button control visible/hidden within a Datagr
id?


Wells,
 
    The easiest (nasty) way to do this is to add a <% %> block in your
ItemTemplate to do a test:
 
<% If (SomeCondition) %>
    <asp:Button RunAt="server" />
<% End If %>
 
    Of course if you want to distance yourself from crappy ASP stuff, then
you'll want to not have any blocks of <% %> in your *.aspx files at all.  To
do this, you'll need to hook the ItemCreated event of the DataGrid, and
using the arguments passed to the event (the event fires every time a new
row is added to the data grid, among other things) you can test and see if a
condition is met for the current row to show or hide the <asp:Button> you
have in your <ItemTemplate>.
 
HTH,
 
- Chuck

-----Original Message-----
From: Oliver, Wells [mailto:WOliver@l...]
Sent: Wednesday, July 17, 2002 11:39 AM
To: ASP+
Subject: [aspx] Making a Button control visible/hidden within a Datagrid?



I have a datagrid displaying some data (bulletin board posts). Within each
row, I have a button which allows editing of that data.

However, I want only the users who made the post to have the button
displayed on that row. The user's name is in the session and is also a
column in the datagrid, so I can match the two strings to determine whether
or not to display the Edit button for that row.

Any ideas? Thanks. 

Wells Oliver 
Web Application Programmer 
Leviton Voice & Data 
xxx-xxx-xxxx 
http://www.levitonvoicedata.com <http://www.levitonvoicedata.com>  

--- Change your mail options at http://p2p.wrox.com/manager.asp or to
unsubscribe send a blank email to  

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Message #7 by "Mingkun Goh" <mangokun@h...> on Thu, 18 Jul 2002 20:47:39

Here is some sample code which I hope can be of use to you.

    Dim CurUserName As String

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load
        CurUserName = Session("UserName")

        If Not Page.IsPostBack Then
            ' Get the list of users from a web service
            DsUsers1 = ws.GetUsers()
            DataGrid1.DataBind()
        End If

    End Sub

    Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As 
System.Web.UI.WebControls.DataListItemEventArgs) Handles 
DataList1.ItemDataBound

        ' Match the two strings to determine whether
        ' the current user is the one who made this post 
        If dsUsers.Tables(0).Rows(e.Item.ItemIndex)("UserName") <> 
CurUserName Then

            If Not IsNothing(e.Item.FindControl("btnEdit")) Then

                ' Cast the control to its specific type
                Dim buttonEdit As Button = CType(e.Item.FindControl
("btnEdit"), Button)
                ' Change any of its properties
                buttonEdit.Visible = False

            End If

        End If

    End Sub


btnEdit will be the id of the button in the DataList Item 
Template.


Similar usage of the DataList1_ItemDataBound event is also found in these 
threads:

<headertemplate> - loadtemplate
http://p2p.wrox.com/archive/aspx/2002-05/96.asp

populating a drop down list from within a datagrid
http://p2p.wrox.com/archive/aspx/2002-05/59.asp



Previous message:
I have a datagrid displaying some data (bulletin board posts). Within each
row, I have a button which allows editing of that data.

However, I want only the users who made the post to have the button
displayed on that row. The user's name is in the session and is also a
column in the datagrid, so I can match the two strings to determine whether
or not to display the Edit button for that row.

Any ideas? Thanks.

Wells Oliver
Web Application Programmer
Leviton Voice & Data
xxx-xxx-xxxx
http://www.levitonvoicedata.com

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