I have a pretty simple ASP.NET Web Form that looks a bit like the following:
<%# Page Language="C#" AutoEventWireup="true" CodeFile="example.aspx.cs" Inherits="example" %>
<form runat="server">
<asp:GridView runat="server" id="grid" AutoGenerateColumns="false" OnRowCommand="DoStuff">
<Columns>
<asp:ButtonField Text="Do stuff" />
</Columns>
</asp:GridView>
</form>
(In PageLoad I call grid.DataBind(), and the event handler DoStuff is unremarkable.)
When I view this in Internet Explorer and click the ButtonField (which renders as a link), the event handler fires as expected. When I click it in Firefox, nothing happens.
If I turn on Firebug's Javascript debugging console then click the link, it shows an error in the Javascript onclick handler that's auto-generated by ASP.NET:
theForm is undefined
__doPostBack("grid", "$0")
javascript:__doPostBack('grid', '$0')()
if (!theForm.onsubmit || (theForm.onsubmit() != false)) {\r\n
Why does this happen and how can I make the ButtonField work in Firefox?
(N.B. I'm asking this question in order to answer it myself: I've already discovered why I was seeing the above error, and wanted to record it for the benefit of myself and others. Feel free to add other answers if you know other gotchas with ASP.NET and Firefox.)
This is due to a difference in how the browsers handle Javascript in the presence of invalid HTML: specifically, when the form is not surrounded with <html> and <body> tags. Without these tags, Firefox seems to try to initialise the variable theForm before the form actually exists.
Adding the proper <html> and <body> tags around the form (as is required for valid HTML in any case) makes the click handler work in both IE and Firefox.
Notes:
obviously invalid HTML is a worst practice for many other reasons. The page I was developing was intended to be used with a Master page which rendered the rest of the surrounding HTML, but (for various reasons) I was testing it in isolation from the Master page.
I tried reproducing the same problem with a simple <asp:Button runat="server">, but that triggers a full page-refreshing PostBack, so it doesn't hit the same error. Being a Web Forms n00b I don't know what's special about a GridView (or this use case) that makes it behave differently (i.e. sets up an onclick handler to handle the click without a page load).
I've marked this as wiki in case anyone else can explain this better than I.
Related
I have an asp button that looks like this:
Default.aspx
<asp:button id="button1" runat="server" Text="clickme" onclick="function" />
Default.aspx.cs
protected void function(object sender EventArgs e)
{
// Do some calculation
}
However, whenever I press the button, the entire page gets refreshed. I have looked on this site and found many solutions, but none of them really works for my project. Here are some of the suggested solutions:
set onclick="return false;" // but then how do I run the function in the code-behind?
use !IsPostBack in Page_Load // but the page still refreshes completely. I don't want Page_Load to be called at all.
Disable AutoEventWireup. // making this true or false doesn't make a difference.
Does anyone have a solution to this, or is it really impossible?
I would place the control inside of an Update panel.
To do so, you would also need a script manager above it, so something like this:
<asp:ScriptManager runat="server" ID="sm">
</asp:ScriptManager>
<asp:updatepanel runat="server">
<ContentTemplate>
<asp:button id="button1" runat="server" Text="clickme" onclick="function" />
</ContentTemplate>
</asp:updatepanel>
if a control inside the update panel does a postback, it will only reload the part of the page inside of the upate panel.Here is a link you may find useful from the MSDN site.
I think there is a fundamental misunderstanding here of how ASP.Net works.
When a user first requests your page, an instance of your Page class is created. The ASP.Net framework runs through the page lifecycle with this page instance in order to generate html. The html response is then sent to the user's browser. When the browser receives the response it renders the page for the user. Here's the key: by the time rendering is complete, your page class instance was probably already collected by the .Net garbage collector. It's gone, never to be seen again.
From here on out, everything your page does that needs to run on the server, including your method, is the result of an entirely new http request from the browser. The user clicks the button, a new http request is posted to the web server, the entire page lifecycle runs again, from beginning to end, with a brand new instance of the page class, and an entirely new response is sent to the browser to be re-rendered from scratch. That's how ASP.Net (and pretty much any other web-based technology) works at its core.
Fortunately, there are some things you can do to get around this. One option is to put most of your current Page_Load code into an if (!IsPostBack) { } block. Another option is to set up your method with the [WebMethod] attribute and make an ajax request to the method from the button. Other options include calling web services from custom javascript and ASP.Net UpdatePanel controls.
What works best will depend on what other things are on the page that user might have changed.
That is normal behavior for asp.net, you are actually causing a postback of the the page in order for the associated event to be called on the server.
I would suggest working with update panels but if you just need something to happen on the backend without it causing any major change on the web page, I would use jquery and a web service. The main reason for me is that update panels create huge viewstate objects.
Have a look here for asp.net ajax : http://www.asp.net/ajax
And here for an example of jquery and wcf : http://www.codeproject.com/Articles/132809/Calling-WCF-Services-using-jQuery
I have a similar problem. this answer helps me a lot. in your asp button.<asp:button id="button1" runat="server" Text="clickme" OnClientClick="return SomeMethod();" /> and in the SomeMethod which is a js method do your logic like manipulating your page then return false as the mentioned answer suggest.
I have a button on an ascx control that calls a method on the onClick event:
<asp:Button id="bUpdateText" onClick="FUpdate" ValidationGroup="Update" CausesValidation="False" Text="Update" cssclass="button" runat="server" />
Normally I use this control on it's own page and the button works. This time round however, I am loading this control into a Div that is present on the home page of my site (that way I can show the contents with a little bit of JQuery). However, when I bring the control in this way, the onClick event doesn't fire and I am not sure what could cause that.
Sorry I don't have any code sample but the nature of the site makes it difficult to provide any that would make sense.
In short, what would stop this event firing now?
p.s I have tried adding validation groups to all other buttons and validation controls on the page and there is only ONE form present on the page.
EDIT: I have only just added the validation stuff in to see if that does anything. By default it has been like this and still didn't work:
<asp:Button id="bUpdateText" onClick="FUpdate" Text="Update" cssclass="button" runat="server" />
As mentioned as well, this works when I use this control on it's own page (loaded directly into Default.aspx) so I don't think the case of onClick matters.
EDIT2: I have just noticed that when I click this button, other validation controls on my page are being triggered even though they have their own DIFFERENT validation group?! Taking these controls out doesn't help though.
Thanks.
I have found out what is causing the issue.
This control that I am now including is called on the Page_Finalize() and I am guessing that by this point the viewstate has forgotten it needs to do anything. Loading this control on the page load sorts it out.
Thanks for looking.
To start, if you set the 'causesValidation' property to false, you do not need a validation group.
Additionally, I believe that ASP cares about case when dealing with the OnClick command.
i.e. it should be OnClick not onClick
Yeah, annoying and small, but that might be your problem
You can use Firebug to see what happen in Update validationGroup. it looks like your page execute only client-side button click because of Update validationGroup.
I have a page with different placeholders. In one of them, I have a link that I want to open a modal popup in a second placeholder (using the ajaxtoolkit ModalPopupExtender) :
<asp:Content ID="content1" ContentPlaceHolderID="placeholder1" Runat="Server">
<asp:LinkButton ID="link" runat="server" Text="Popup link" />
</asp:Content>
<asp:Content ID="content2" ContentPlaceHolderID="placeholder2" Runat="Server">
<asp:Panel ID="panel" runat="server" Text="Popup content" />
<ajaxToolkit:ModalPopupExtender ID="popup" runat="sever"
TargetControlID="link"
PopupControlID="panel"
/>
</asp:Content>
When doing as above, it fires me an exception, saying that popup cannot find link (which I understand, because they are in two different placeholders).
How can I make this work ? I can think of something find FindControl in the code behind, but I don't really like to use this function, as it is pretty computationally expensive (especially with my nested layout).
One issue is that your TargetControlID and PopupControlIDs are reversed. TargetControlID is the ID of the item that you want to 'Modal Pop', in your case that would be Panel1. The PopupControlID is the ID of the control that would trigger the ModalPopup, in your case that would be "Link"
But you still have a few options if that doesn't work, I have fired a modal located in a different update panel before using the method below. Though not the exact same issue, this workaround may help you (I am assuming you have a script manager on your page).
Create a hidden element in Content2 with ID="hiddenLink"
Set your ModalExtender PopupControlID="hiddenLink"
In the codeBehind for "link" in content1, add an onClick event with the following
ModalPopup1.show()
If you are using updatePanels, this will cause the ModalPopup to display in AJAX fashion without page refresh.But you would still get a full postback worht of data between the client and the server.
Method 2, you could use a javascript function to show to Modal as well. Add a behaviorID="MyModal1" (or whatever you want to call it) to your Modalpopup definition. Then change your link:
<asp:LinkButton ID="link" runat="server" Text="Popup link" OnClientClick="$get('MyModal1').show(); return false;"/>
Note: The return false in the above example prevents the .NET page from performing a postback.
The following .NET 3.5 code, placed in an aspx file, will trigger a JavaScript error when the page is loaded (for users who have JavaScript enabled):
<noscript>
<asp:TextBox ID="txt" runat="server"></asp:TextBox>
<asp:RequiredFieldValidator ID="txt_RequiredFieldValidator" runat="server"
ControlToValidate="txt"></asp:RequiredFieldValidator>
<asp:Button ID="btn" runat="server" Text="Button" />
</noscript>
The error happens because the JavaScript generated by the ASP.NET validator control does not contain a null check on before the second code line below:
var ctl00_body_txt_RequiredFieldValidator =
document.all ?
document.all["ctl00_body_txt_RequiredFieldValidator"] :
document.getElementById("ctl00_body_txt_RequiredFieldValidator");
ctl00_body_txt_RequiredFieldValidator.controltovalidate = "ctl00_body_txt";
Can anyone suggest a workaround to this?
Footnote: Why am I doing this? For my non-JavaScript users I am replacing some AJAX functionality with some different UI components, which need validation.
You should add the following to the RequiredFieldValidator:
enableclientscript="false"
Seeing as you are using these in <noscript> tags, there is no point in supplying client side vaildation of the controls - they are only going to display if JS is turned off.
This will force the validation to happen (automatically) on the server side for you.
Just make sure you call "Page.IsValid" before you process the response.
See BaseValidator.EnableClientScript for more details.
The javascript is looking for an element contained in the noscript? AFAIK there's no clean way to detect script support from the server side.
I think you'll need to build in a redirect (I've seen this done with a meta-refresh in a header noscript if you don't mind a validation failure) to push noscript users to a "please turnscript on page" or do some surgery to loosen up the validation/control binding which may take some amount of wheel reinventing. This is one of those areas where asp.net's tight coupling between controller and view really punishes.
I have a gridview that is within an updatepanel for a modal popup I have on a page.
The issue is that the entire page refreshes every time I click an imagebutton that is within my gridview. This causes my entire page to load and since I have grayed out the rest of the page so that the user cannot click on it this is very annoying.
Does any one know what I am missing.
Edit: I entered a better solution at the bottom
Make sure you have the following set on the UpdatePanel:
ChildrenAsTriggers=false and UpdateMode=Conditional
do you have ChildrenAsTriggers="false" on the UpdatePanel?
Are there any javascript errors on the page?
I had this problem and came across the following article:
http://bloggingabout.net/blogs/rick/archive/2008/04/02/linkbutton-inside-updatepanel-results-in-full-postback-updatepanel-not-triggered.aspx
My button wasn't dynamically created in the code like in this example, but when I checked the code in the aspx sure enough it was missing an ID property. On adding the ID the postback became asynchronous and started to behave as expected.
So, in summary, check your button has an ID!
Are you testing in Firefox or IE? We have a similar issue where the entire page refreshes in Firefox (but not IE). To get around it we use a hidden asp:button with the useSubmitBehavior="false" set.
<asp:Button ID="btnRefresh" runat="server" OnClick="btnRefresh_Click" Style="display: none" UseSubmitBehavior="false" />
Several months later this problem was fixed. The project I was working in was a previous v1.1 which was converted with 2.0. However, in the web.config this line remained:
<xhtmlConformance mode="Legacy"/>
When it was commented out all of the bugs that we seemed to have with the ajax control toolkit disappeared
Is the Modal Window popped up using the IE Modal window? Or is it a DIV that you are showing?
If it is an IE Modal Pop up you need to ensure you have
<base target="_self" />
To make sure the post back are to the modal page.
If it is a DIV make sure you have your XHTML correct or it might not know what to update.
I would leave the onClick and set it as the trigger for the updatePanel.
That's odd that it works in FF and not IE. That is opposite from the behavior we experience.
UpdatePanels can be sensitive to malformed HTML. Do a View Source from your browser and run it through something like the W3C validator to look for anything weird (unclosed div or table being the usual suspects)
If you use Firefox, there's a HTML validator Extension/AddOn available that works quite nicely.
For reference..
I've also noticed, when using the dreaded <asp:UpdatePanel ... /> and <asp:LinkButton ... />, that as well as UpdateMode="Conditional" on the UpdatePanel the following other changes are required:
ViewStateMode="Enabled" is required on <asp:Content ... /> (I've set it to Disabled in the MasterPage)
ClientIDMode="Static" had to be removed from <%# Page ... />
To prevent post-backs add return false to the onclick event.
button.attribute.add("onclick","return false;");
Sample:
string PopupURL = Common.GetAppPopupPath() + "Popups/StockChart.aspx?s=" + symbol;
hlLargeChart.Attributes.Add("onclick", String.Format("ShowPopupStdControls(PCStockChartWindow,'{0}');return false;", PopupURL));