I have a standard ASP.Net DataPager with a standard ListView (using a DataTable as a data source).
When I set PageSize="24" in the design code:
<asp:DataPager runat="server" ID="DataPager1" PagedControlID="ListView1" QueryStringField="page" PageSize="24" >
the paging works as advertised.
However, when I then change that in code, in the Page_Load, eg:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
DataPager1.PageSize = 48
End Sub
the paging ceases to work completely, while the initial loaded data set is indeed 48 items.
I can't see anything in the code which would affect this, so I'm wondering if I'm missing something - should I be changing something else?
Regards
Moo
Protected Sub DataPager1_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles DataPager1.Init
DataPager1.PageSize = 48
End Sub
I managed to get this working by setting the page size property in the init event for the datapager.
This sort of error I usually find is a data-binding issue... either binding when you shouldn't, or not re-binding when appropriate. Hard to tell from your little snippet of code.
I am unfamiliar with the DataPager object, but I suspect it must rebind the data when you set the PageSize. If so, then every time the page loads it is re-binding and you are losing events. Have you tried this?
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack
DataPager1.PageSize = 48
End If
End Sub
Related
I have a button that sets a session variable when clicked. But for some reason, I have to click it twice in order for the save to actually happen. Is there anyway around this?
Thanks
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If CInt(Session("save")) <> 1 Then
'save something ...
End If
End Sub
Private Sub btnSave_Click(sender As Object, e As System.EventArgs) Handles btnSave.Click
Session("save") = 1
End Sub
Page_Load runs before btnSave_Click. You can see more information about the ordering of events in MSDN.
In other words, when btnSave is clicked, the postback runs the Page_Load then the btnSave_Click method. To fix this problem, move the code 'save something ... into the btnSave_Click method.
Is there any reason why an if then statement would fire regardless:
Its inside my Page_load:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim a As New Clicks
If Request.QueryString("u") IsNot Nothing Then
a.Click(Request.QueryString("u"), Request.ServerVariables("REMOTE_ADDR"), Request.ServerVariables("HTTP_USER_AGENT"))
Response.Redirect(urls.GetURL(Request.QueryString("u")))
End If
End Sub
As a result, I am get 126 instances of a.Click per page load when "u" isnt present?
I have tried to move to other Page Events but same result
Created a workaround by encasing if statement in the original if statement to capture the unwanted items.
Not the perfect solution but is working
I have a DropDownList with an SelectedIndexChanged event listener
<asp:DropDownList ID="LoanOptionCombo" runat="server" AutoProstBack="True">
Listener
Protected Sub LoanOptionCombo_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles LoanOptionCombo.SelectedIndexChanged
' hello world, no code here yet
End Sub
My Page_Load event
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
' parse a .txt file and populate the DropDownList
InitializeLoanOptions()
End Sub
When the form initially loads, the loan options are loaded into the DropDownList (currently 4).
Whenever the user selects a loan option for the DropDownList, the DrowDownList gets re-initialized somehow, adding the same 4 options to the list again.
Each time the user selects another option, the same 4 options are re-added to the list.
I'm assuming the Page_Load event is being called again because that's the only place where I'm actually adding the DropDownList items. No other place in code interacts with the DrowDownList.Items.
How can I listen to the SelectedIndexChanged event on my DropDownList but avoid re-initializing my whole form?
you need to change your Page_Load as below
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
' parse a .txt file and populate the DropDownList
If Not IsPostBack
InitializeLoanOptions()
End If
End Sub
You can use IsPostBack property in page load event.
Only data bind to your drop down when your page is load.
check theses links
http://msdn.microsoft.com/en-us/library/system.web.ui.page.ispostback.aspx
http://www.aspnet101.com/2007/03/if-not-page-ispostback/
Check IsPostBack property on page_load.
If Not IsPostBack
// Load your drop drop list here....
End If
I have a Treeview with "populateOnDemand" set to true. I want this treeview to keep its state (nodes expanded/collapsed) from one page to another. Viewstate doesn't work because the treeview is different for each page. Here is my code at the moment.
ASPX page :
<asp:TreeView
ID="arbre"
EnableViewState="true"
PopulateNodesFromClient="true"
runat="server" />
Code behind :
Protected Sub arbre_TreeNodeCollapsed(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.TreeNodeEventArgs) Handles arbre.TreeNodeCollapsed
CType(Session("listeNoeudsOuverts"), Hashtable)(e.Node.Value) = True
End Sub
Protected Sub arbre_TreeNodeExpanded(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.TreeNodeEventArgs) Handles arbre.TreeNodeExpanded
CType(Session("listeNoeudsOuverts"), Hashtable)(e.Node.Value) = False
End Sub
Protected Sub arbre_TreeNodePopulate(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.TreeNodeEventArgs) Handles arbre.TreeNodePopulate
// code to populate nodes
CType(Session("listeNoeudsOuverts"), Hashtable)(e.Node.Value) = True
End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Session("listeNoeudsOuverts") Is Nothing Then
Session("listeNoeudsOuverts") = New Hashtable()
End If
// other stuff
End Sub
This works well, buf I wish I could avoid the postback everytime the user expands or collapses a node. I know I can set EnebleClientScript to true and manage the events client side in Javascript but I won't be able to use my session variable anymore. Is there a way to achieve this ?
Thank you
I will answer myself to a certain extent.
I've done some tests and research, EnableClientScript is true by default, and indeed means that expand and collapse actions are processed client side, by Javascript code that is automaticalt generated by the .Net framework. You can't edit it.
Apparently, if you need to add custom actions when a user expands or collapses anode, you have to use TreeNodeExpanded and TreeNodeCollapsed events, like i did above, and can't avoid postbacks because they are triggered server-side.
I have a checkbox and a panel inside of a FormView control, and I need to access them from the code behind in order to use the checkbox to determine whether or not the panel is visible. This is the code that I originally used, but since I put the controls inside of the FormView, it no longer works.
Protected Sub checkGenEd_CheckedChanged(ByVal sender As Object, _
ByVal e As System.EventArgs)
If checkGenEd.Checked = True Then
panelOutcome.Visible = True
Else
panelOutcome.Visible = False
End If
End Sub
I've started to figure this out based on other questions I looked up on here, but all of them were in C# instead of VB, so this is as far as I got:
Protected Sub FormView1_DataBound(ByVal sender As Object, ByVal e As System.EventArgs) Handles FormView1.DataBound
If FormView1.CurrentMode = FormViewMode.Edit Then
End If
End Sub
So yeah I'm not sure exactly how to finish it. I'm sorry, this might be pretty basic, but I'm new at this and any help would be appreciated!
EDIT: here's my code now:
Protected Sub FormView1_DataBound(ByVal sender As Object, ByVal e As System.EventArgs) Handles FormView1.DataBound
If FormView1.CurrentMode = FormViewMode.Edit Then
CheckBox checkGenEd = formview1.FindControl("checkGenEd");
Panel panelOutcome = formview1.FindControl("panelOutcome");
End If
End Sub
It's also saying that checkGenEd and panelOutcome are not declared.
EDIT: I changed my code to this but it still doesn't work:
Protected Sub FormView1_DataBound(ByVal sender As Object, ByVal e As System.EventArgs) Handles FormView1.DataBound
If FormView1.CurrentMode = FormViewMode.Edit Then
Dim checkGenEd As CheckBox = FormView1.FindControl("checkGenEd")
Dim panelOutcome As Panel = FormView1.FindControl("panelOutcome")
If checkGenEd.Checked = True Then
panelOutcome.Visible = True
Else
panelOutcome.Visible = False
End If
End If
End Sub
There aren't any errors anymore, but nothing happens when I click the checkbox. I think there needs to be some kind of event to trigger it but I don't know how you can put an event handler inside of an event handler.
With FormView, you have to use find control, as in:
CheckBox checkGenEd = (CheckBox)formview1.FindControl("checkGenEd");
Panel panelOutcome = (Panel)formview1.FindControl("panelOutcome");
You cannot reference a control directly by ID.
HTH.
In VB you need use Directcast
Dim chk As Checkbox = DirectCast(Me.FormView1.FindControl("checkgen"), Checkbox)
FormView has its own event framework. A normal control within a FormView won't generate the postback events you are looking for. I initially made the same mistake. I wanted, like you, to generate some kind of postback that could be intercepted at the server end. Once we get back to the server we can look at the values in checkboxes etc depending on whatever business rules apply. This is what I did.
First of all put all relevant controls within an
<EditItemTemplate>
section within the FormView. (There are other Template tags that may be more appropriate). To generate the postback have a button (for example) like the one below. (This has to be within the EditItemTemplate section as well):
<asp:linkbutton id="UpdateButton"
text="Update"
commandname="Update"
runat="server"/>
You can intercept this at the server with the FormView event ItemCommand. For example:
Private Sub FormView1_ItemCommand(sender As Object, e As System.Web.UI.WebControls.FormViewCommandEventArgs) Handles FormView1.ItemCommand
'your code here
End Sub
Once you are back at the server you can then start looking at the various controls to see what they hold, using findControl if necessary. The button command shown above is an example so you might want to use another control.