Develop Reference

ASP.NET UpdatePanel not working, it refreshes the whole page

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();

Gridview outside UpdatePanel not showing

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.

Why is my DropDownList in asp.net not refreshing?

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

Right order to add/remove controls to updatepanel on update

I've been trying to add/remove controls to an updatepanel when updating it. Those controls are dynamically filled depending on the info in the page session.
The Updatepanel_Load event is triggered correctly but the controls I've changed won't show properly. They'll only show after a full postback!
Now I know that you need an onInit event to add / alter controls on the page but is this also necessary for an updatepanel? Can someone please explain the right order to do this?
ORDER RIGHT NOW:
Button click
LoginProcedure over ajax
OnInit
UpdatePanel1_Load (Generates controls)
onInit.
So no controls are added / altered until full post back. What is the correct order / method to add / alter controls within an updatepanel without a full postback?

add async postback to your updatePanel like:
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Label ID="Label1" runat="server" Text="Init..."></asp:Label>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="TextBoxTrigger" EventName="TextChanged" />
</Triggers>
</asp:UpdatePanel>

Search using Update Panels

Is it possible to use an UpdatePanel that has like a few text boxes, and a search button, and then perhaps another UpdatePanel that has a gridview in it to return the results of what was searched. When the user clicks search it hides the boxes, and displays the gridview. Can I do this with UpdatePanels? I am using c# for my coding. Or should I be doing this another way?

You only need one UpdatePanel in that case and setup a Trigger to your search Button.
Put only the controls that will be refreshed in your UpdatePanel.
Example:
<asp:TextBox ID="txtSearchCriteria" runat="server" />
<asp:Button ID="btnSearch" runat="server" OnClick="btnSearch_Click" />
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnSearch" EventName="Click" />
</Triggers>
<ContentTemplate>
<asp:GridView ID="grdSearchResults" runat="server">
</asp:GridView>
</ContentTemplate>
</asp:UpdatePanel>
Implement the btnSearch_Click function to execute your search and bind the results to the GridView. The UpdatePanel will handle the ajax call and replacing of the HTML that the GridView will produce.
You want to keep as much out of the UpdatePanel as possible and only include what will actually change because it is transmitting that HTML with each update so it's a waste of resources if you are not actually doing anything to those controls with each action. That is why a trigger is best to be used in this case which will hook the UpdatePanel to the Click event outside of the UpdatePanel scope.
Read up more on UpdatePanel and how triggers work on MSDN.

If I understand the question correctly, you can do that with two <asp:Panel> controls inside the <UpdatePanel>. One panel for the textboxes, and the other for the gridview. You set which panel to show in the codebehind, depending on whether you're expecting your user to enter search criteria, or review the search results.

Yes you can.
You also could use just one update panel. Since you the Search Form (could be in a Panel) and the GridView inside the UpdatePanel.