I have a simple DropDownList on my asp.net webpage:
It looks like this:
<asp:UpdatePanel ID="UpdatePanel4" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:DropDownList ID="FriendList" runat="server"
EnableViewState="False" Height="30px" Width="10%"
OnTextChanged="FriendListSwitch" AutoPostBack="True">
</asp:DropDownList>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnSend" />
</Triggers>
<--!The button is a stub, I actually need to load it from the codebehind-->
</asp:UpdatePanel>
Then I have the codebehind like this:
void OnRosterItem(object sender, agsXMPP.protocol.iq.roster.RosterItem item)
{
FriendList.Items.Add(new ListItem(String.Format("{0}", item.Jid.User), ""));
FriendList.DataBind();
}
While debugging I can see that 'FriendList' is being filled, and also that 'btnSend' is being clicked.
Yet my DropDownList is not refilling itself, it just stays empty, why is it not refreshing?
Edit: I'd rather remove the button and replace it with
void OnRosterEnd(object sender)
{
UpdatePanel5.Update();
}
But then I keep getting
The Update method can only be called on UpdatePanel with ID 'X' before Render.
Solved, the DataBind() only worked inside a Page_Load for me.
The button 'btnSend' should be inside the update panel
try using OnSelectedIndexChanged event instead of OnTextChanged
If you need the button to update the dropdown then it needs to be in the update panel
If you need the dropdown list to be the trigger then asyncpostback trigger needs to have the control id of the dropdown list
Related
I'm new in using UpdatePanel, I Have 2 DropDownList:
DropDownList_1 and DropDownList_2
where DropDownList_2 content will be dependent to DropDownList_1 selected value, here is my code:
ASPX:
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:DropDownList ID="DropDownList_1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DropDownList_1_SelectedIndexChanged" DataSourceID="businessgroup" DataTextField="BusinessGroupName" DataValueField="Id"></asp:DropDownList>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="DropDownList_1" EventName="SelectedIndexChanged" />
</Triggers>
</asp:UpdatePanel>
<asp:DropDownList ID="DropDownList_2" runat="server" DataSourceID="jobposition" DataTextField="JobPositionName" DataValueField="Id"></asp:DropDownList>
CS:
protected void DropDownList_1_SelectedIndexChanged(object sender, EventArgs e)
{
SqlDataSource1.SelectCommand = "SELECT DISTINCT * FROM [JobPosition] WHERE BusinessGroupID ="+DropDownList_1.SelectedValue;
DropDownList_2.DataBind();
}
its working as stated above but what I doesn't want in my output is the whole page refreshes, I also tried removing AutoPostBack="true" in my DropDownList_1 but it stops working, what am I doing wrong in here? Thanks!
EDIT:
I also tried moving the DropDownList_2 inside UpdatePanel's ContentTemplate but still the whole page is refreshing.
Here is how you should do:
If you want to refresh the second drop-down, than the second drop-down should be inside an update panel
Set AutoPostBack="true" only for the second drop-down
Set UpdateMode="Conditional" for the update panel (otherwise they will refresh every time)
Set the AsyncPostBackTrigger of the panel to point to the first drop-down SelectedIndexChanged event
Set ChildrenAsTriggers="true" for the Update panel
:
<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="true"></asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="true">
<ContentTemplate>
<asp:DropDownList ID="DropDownList1" runat="server" OnSelectedIndexChanged="DropDownList_1_SelectedIndexChanged" DataSourceID="businessgroup" DataTextField="BusinessGroupName" DataValueField="Id"></asp:DropDownList>
<asp:DropDownList ID="DropDownList_2" runat="server" AutoPostBack="true" DataSourceID="jobposition" DataTextField="JobPositionName" DataValueField="Id"></asp:DropDownList>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="DropDownList_1" EventName="SelectedIndexChanged" />
</Triggers>
</asp:UpdatePanel>
The controls should reside in the same update panel, it's simpler this way.
I found the fix, thanks to Cristina for reminding me to check the console errors. And just for reference to anyone who is having the same problem here is what I've done:
I have missing Ajax libraries, so I imported the MicrosoftAjax.js and MicrosoftAjaxWebService in this folder Scripts>WebForms>MSAjax.
After I imported the necessary Ajax library I've got this console error:
MicrosoftAjaxWebForms.js:6 Uncaught
Sys.WebForms.PageRequestManagerServerErrorException:
Sys.WebForms.PageRequestManagerServerErrorException: Invalid postback
or callback argument. Event validation is enabled using in configuration or <%# Page
EnableEventValidation="true" %> in a page. For security purposes,
this feature verifies that arguments to postback or callback events
originate from the server control that originally rendered them. If
the data is valid and expected, use the
ClientScriptManager.RegisterForEventValidation method in order to
register the postback or callback data for validation.
What I did is add EnableEventValidation="false" inside this Ajax page, in <%Page %> directive.
And after that I have no longer full page reload and all is working now on how I wanted.
If your panel still posts back after you've set it up as per guidelines, check that you have not set ClientIDMode="Static" either for the specific control performing the callback or by causing the ClientIDMode to default to static inherited from either in web.config, the Page or parent containers.
Search your solution for ClientIDMode="Static" and either change this for inherited controls including the one triggering the postback, or explicitly set ClientIDMode="Predictable" or ClientIDMode="AutoID" for each of your controls that trigger a postback.
While you are working with update panel you have to register your events while refreshing the page for that you have to use Microsoft's PageRequestManager
to re-subscribe every update.
You have to initialize your event in the document.ready(function(){})
of the javascript.
Ex: var test=Sys.WebForms.PageRequestManager.getInstance();
I have two drop down lists,the first one is ddlSubjectArea and below is it's source code:
<asp:DropDownList ID="ddlSubjectArea" runat="server" AutoPostBack="True" Height="20px"
OnSelectedIndexChanged="ddlSubjectArea_SelectedIndexChanged" Width="160px"
meta:resourcekey="ddlSubjectAreaResource1" class="notranslate">
</asp:DropDownList>
Here is the code for the second one:
<asp:UpdatePanel ID="UpdatePanel3" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:DropDownList ID="ddlCompetency1" runat="server" Width="150px">
</asp:DropDownList>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="ddlSubjectArea" runat="server" />
</Triggers>
</asp:UpdatePanel>
And this is the code for the selectedindexchanged event of the first dropdownlist.
protected void ddlSubjectArea_SelectedIndexChanged(object sender, EventArgs e)
{
tblSubjectMasterDLL.BindSubjectOnSubjectArea(ddlSubjectName, Convert.ToInt32(ddlSubjectArea.SelectedItem.Value));
bIsMultipleCompetency = tblSubjectAreaMasterDLL.IsMultipleCompetency(Convert.ToInt32(ddlSubjectArea.SelectedValue));
MultipleCompetencySetting();
}
The visibility of the second dropdownlist depends on the first dropdownlist's selected index.The selectedindexchanged event fires once but after that it does not fire.I have tried selecting different values every time but had no success.Where am I going wrong?
Another piece of information that I would like to provide is that even the page load event is getting called only once.Also if I remove the update panels,everything works normally.
I would like to add one more piece of information:If I set EnableEventValidation=false for the page,things start working as expected.I have also heard that setting EnableEventValidation to false is not recommended.
I have an ItemCommand event in a button found in a listview.
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:ListView ID="systemsView" runat="server"
onitemcommand="systemsView_ItemCommand">
<ItemTemplate>
<asp:Button ID="btnView" runat="server" Text='<%#Eval("SYSTEM_DESC") %>' CommandArgument='<%# Eval("ROW_ID")%>'
class="systemButtonStyle" />
</ItemTemplate>
</asp:ListView>
</ContentTemplate>
</asp:UpdatePanel>
When the itemCommand is fired I want to bind another gridview which is not inside the update panel. The gridview is not showing when the event is fired. Any ideas how I could solve this problem please?
Since UpdatePanels only perform a PostBack on controls within their ContentTemplate, all controls that are expected to be updated by a Partial PostBack must be housed within the same UpdatePanel's ContentTemplate.
If you need to update something outside of an UpdatePanel with an action that occurs within it's Partial PostBack, you will have to rethink your use of the UpdatePanel.
Two solutions:
Add the other GridView to the UpdatePanel's ContentTemplate.
Remove the UpdatePanel entirely and use the normal PostBack.
I'm adding a variable number of update panels in Page_Init.
I already have a script manager in my master page.
The problem is that when I try to add a trigger like:
AsyncPostBackTrigger trig2 = new AsyncPostBackTrigger();
trig2.ControlID = ddl22.UniqueID;
trig2.EventName = "SelectedIndexChanged";
up2.Triggers.Add(trig2);
where ddl22 is a DropDownList, the event never seems to trigger the UpdatePanel.
In the UpdatePanel I have another DropDownList the data of which i want to change when the trigger happens.
The funny thing is that in the master page I have a timer. This timer is only supposed to trigger the UpdatePanel in the master but it seems to trigger all of my update panels. However, even when it triggers the update panel in the child page, the second DropDownList does not change its data.
The data is databound to the DropDownList in the UpdatePanel in page_init. It is bound to an objectdatasource which uses the selected item in the first DropDownList as a parameter to determine what data it should bind.
Did you set AutoPostBack="True" for your drop down list? I suspect this is the issue.
Also set your update panel mode to conditional-UpdateMode="Conditional" so that i does not affect other update panels.
Try this,
In Source Code,
<asp:UpdatePanel ID="up2" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:DropDownList ID="ddl1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddl1_SelectedIndexChanged"></asp:DropDownList>
<asp:DropDownList ID="ddl2" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddl2_SelectedIndexChanged"></asp:DropDownList>
</ContentTemplate>
<Triggers>
<asp:PostBackTrigger ControlID="ddl2" />
</Triggers>
</asp:UpdatePanel>
You can manually call the UpdatePanel to refresh without specifying a trigger on a postBack event. Firstly, set the UpdateMode property to 'Conditional', then you can just call an update on your updatepanel from code behind like
MyUpdatePanel.Update();
I have Repeater with Dropdown within
<ItemTemplate>
<asp:DropDownList runat="server" ID="ddl_PostponeTime" >
</asp:DropDownList>
</ItemTemplate>
When I fire onCommand Event with Linkbutton and trying to get and locate the DropDown list by repeater item number
ddl.selecteditem.value
I can't get the value I've selected, only the first (and default) Value comes.
Maybe it have something to do with UpdatePanel?
Any Other Ideas?
Wherever you bind your DropDownList, make sure that you're checking for Page.IsPostBack == false. Otherwise, you're always going to get the initial SelectedValue because ASP.NET is helpfully re-loading the whole DropDownList.
Yes, you need to use UpdatePanel. You need something like that:
<asp:UpdatePanel ID="TheUpdatePanel" runat="server"
UpdateMode="Conditional">
<ContentTemplate>
//your controls...
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
On the dropdowns set Autopostback=true.