I have a user control which has html elements like <input type="button".... and i want to set its display property on preRender state.
Would you please explain, what kind things i have to handle this user control? So, in this function
protected override void OnPreRender(EventArgs e) { }
I have only EventArgs e and it doesn't have proper method or properties to bring me the html of user control.
Thank you from now...
The easiest way to control visibility of elements from the server side is to promote them to server controls. For example:
<input id="mybutton" runat="server" type="button" ...
Doing so would allow you to execute a statement like the following in your OnPreRender() event:
mybutton.Visible = false; // removes the element
Or...
mybutton.Style[HtmlTextWriterStyle.Display] = "none"; // styles the element
Related
I'm teaching myself to use a site.master page with child webforms embedded using the ContentPlaceHolderID object. I'm figuring it out, but I have one question; is it possible to put a button on the site.master page that fires code on the codebehind pages of the child forms? If I can do that, it will really simplify what I'm trying to accomplish.
I tried to 'inherit' both codebehinds, but of course that didn't work. Is there a way to do this?
Yes there is a way to do this. You need to set UseSubmitBehavior button property to false and then you can access the control that causes the post back using Request.Params.Get("__EVENTTARGET"); So the code would look like this:
Button definition in Site.Master markup:
<asp:Button ID="MyButton" runat="server" Text="Button" UseSubmitBehavior="false" />
code behind within any inherited page:
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
// in case you have code to be executed on first load
}
else
{
string myButtonCtrl = Request.Params.Get("__EVENTTARGET");
if (myButtonCtrl != null && myButtonCtrl.EndsWith("MyButton"))
{
// MyButton has been clicked!
}
}
}
This has to be the simplest thing in the world but it just isn't working.
I have an outer div to which I want to apply a class to make its display style = none so that it hides all the content within it. It's actually an asp:panel element so I'm assuming I can just set control.CssClass = "my-hidden-class" in the code behind.
I'm actually setting this on a button click handler(depending on certain conditions) But the class is never applied. When I inspect the div element in Firebug it doesn't even have a class attribute. It appears exactly as it is in the .aspx markup (the actual css class is fine & gets applied when I add it declaratively).
Also, I can see the class applied if I set CssClass in the prerender method on the initial get request. So I thought maybe I'll put all the logic in prerender and update the Css Class accordingly. This also doesn't work - the class gets applied on the initial get ok but I can't change it subsequently.
So, to sum up it seems I can't apply class from code behind at all in the event handler and I can only apply it in prerender for the intial get request & this value is persisted on all postbacks.
What am I doing wrong?
Edit: Here's the code -
aspx:
<asp:panel runat="server" ID="TariffContainer"><!--this is the div I want to toggle-->
<cms:ContentBlock ID="currentTariffsInfo" SkinID="Public/OurPrices/CurrentTariffsInfo" runat="server" />
<ucTcrPanel:tcrpanel ID="tcrpanel" PagingEnabled="true" runat="server" />
<div class="quick-price">
<asp:LinkButton runat="server" CausesValidation="false" ID="QuickEnergyPrice" OnClientClick="Javascript:return false;" CssClass="button subcontent"><span>Get a quick energy price</span></asp:LinkButton>
</div>
<div class="not-for-sale">
<cms:ContentBlock ID="preservedTariffsLinkInfo" SkinID="Public/OurPrices/PreservedTariffsLinkInfo" runat="server" />
<p>
<asp:LinkButton runat="server" CausesValidation="false" ID="ViewNotAvailableTariffs" OnClick="RedirectToUnavailableTariffs" cssclass="arrow">View tariffs not available for sale</asp:LinkButton>
</p>
</div>
</asp:panel>
Code Behind:
protected void PostCodeChange_BtnClick(object sender, EventArgs e)
{
if (IsValid)
{
tcrpanel.ApplyPostcodeUpdate(postcode.EnteredPostCode);
tcrpanel.TcrUpdatePanel.Update();
}
else
{
TariffContainer.CssClass = "formContentHidden";
}
}
Update - The button click event is coming from a user control & this is wired up to trigger an update on an update panel - i.e. a partial postback is happening. I'm doing this hiding & showing of the div in the containing aspx page & even though all the server side page events are executing I'm guessing that the content of the page isn't getting re-rendered so I'm not seeing my changes.
The Solution - I ended up squirting a bit of javascript down from the server:
protected void PostCodeChange_BtnClick(object sender, EventArgs e)
{
tcrpanel.ApplyPostcodeUpdate(postcode.EnteredPostCode);
tcrpanel.TcrUpdatePanel.Update();
}
Then in the tcrpanel user control code behind:
public void ApplyPostcodeUpdate(string postcode)
{
if (IsValid)
{
BuildStartUpScript("showTariffContainer();");
}
else
{
BuildStartUpScript("hideTariffContainer();");
}
}
private void BuildStartUpScript(string functionCall)
{
StringBuilder script = new StringBuilder();
script.AppendLine("<script type=\"text/javascript\">");
script.AppendLine(functionCall);
script.AppendLine("</script>");
ScriptManager.RegisterStartupScript(pnlUpdateTcr, pnlUpdateTcr.GetType(), "HideTariffContainerScript", script.ToString(), false);
}
Then in the included JS file:
function hideTariffContainer() {
$("div.formContentVisible").toggleClass().toggleClass("formContentHidden");
}
function showTariffContainer() {
$("div.formContentHidden").toggleClass().toggleClass("formContentVisible");
}
As suspected, the problem was that a partial postback was occurring in which only the contents of the update panel were being re-rendered.
That said, all the server side page lifecycle events were still being invoked. This is what confused me as I could debug and see the CssClass being applied but not being rendered in the html. Just the way Asp.Net update panels work I guess.
I have an ASP.NET control that has an onclick event handler rendered inline on the element. I would like to call that function and have it raise the target control's server side event handler.
<asp:CheckBox ID="Foo"
runat="server"
AutoPostBack="true"
Text="Foo" />
<a href="#"
onclick="javascript:setTimeout('__doPostBack(\'Foo\',\'\')', 0)">Test
</a>
I created the checkbox, looked at the rendered function on the field, and then copied that into the onclick on the anchor element.
The anchor will raise a postback, but the event handler for the check box is not raised.
protected override void OnLoad(EventArgs e)
{
// fires for checkbox
// fires for anchor (the anchor does cause a postback)
}
void Foo_CheckedChanged(object sender, EventArgs e)
{
// fires for checkbox
// does not fire for anchor
}
protected override void OnInit(EventArgs e)
{
this.Foo.CheckedChanged += new EventHandler(Foo_CheckedChanged);
}
Is it possible to do this?
Don't try to manually determine what the javascript should look like for a postback. Use the proper API for the task... in this case, this is exactly what GetPostBackEventReference is for.
myControl.Attributes.Add("onclick", "javascript:" + ClientScript.GetPostBackEventReference(targetControl));
Why not convert the tag to an asp:linkbutton and then have the one handler for both
protected override void OnInit(EventArgs e)
{
this.Foo.CheckedChanged += new EventHandler(Foo_CheckedChanged);
this.Bar.Click+= new EventHandler(Foo_CheckedChanged);
}
The client ID of you checkbox might now be "Foo".
Use the following to make sure you use the correct ClientID for your element
<a href="#"
onclick="javascript:setTimeout('__doPostBack(\'<%= Foo.ClientID %> \',\'\')', 0)">Test
</a>
I am using an ASP.NET ModalPopupExtender on a page and would like to prevent the dialog from hiding when the user presses the ok button in certain conditions. But I can't seem to find a way.
What I am looking for is something like this
ajax:ModalPopupExtender
...
OnOkScript="return confirm('You sure?')"
...
if confirm is false, then the modal dialog doesn't disappear.
From my understanding in your specific situation you would not wire up the button, and just wire up a script to handle the conditional, then you can close it via JS.
The following JavaScript function will allow you to achieve this:
function conditionalHide(clientID)
{
if (confirm('You sure?'))
{
$find(clientID).hide();
}
}
You can wire this up to your asp:Button control in the Page_Load event of your page
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
btnOK.OnClientClick = string.Format("conditionalHide('{0}'); return false;",
panPopup_ModalPopupExtender.ClientID);
}
}
Some notes:
panPopup_ModalPopupExtender is your ModalPopupExtender
The return false; prevents a postback from occurring when the user clicks the button
You could hard-code the ClientID of the ModalPopupExtender, but this introduces an (additional) maintainance headache. The approach shown is the best one that I've found to alleviate this overhead
I am using an ASP.NET AJAX-Enabled Web application (ASP.NET 2.0 and AJAX Toolkit 1.0)
that contains one button and 2 UpdatePanels (UpdatePanel_1 and UpdatePanel_2)
The button is registered with RegisterAsyncPostBackControl in the ScriptManager object
UpdatePanel_1 is in "Conditional" update mode and contains a TextBox.
UpdatePanel_2 is in "Always" update mode and contains another TextBox
When the button is pressed its handler calls UpdatePanel_1.Update() that updates the value of the TextBox based on a randomly selected value in a list;
Also the UpdatePanel_2's TextBox is being updated automatically , also without page refresh
Based on the value of a boolean ViewState variable I would also like to hide/show the UpdatePanels alternatively but
I get the error :
"Sys.InvalidOperationException: COuld not find UpdatePanel with ID 'UpdatePanel_2' (or UpdatePanel_1).
If it is being updated dynamically then it must be inside another UpdatePanel"
How can it be done without adding extra wrapping UpdatePanels?
protected void Page_Load(object sender, EventArgs e)
{
ScriptManager1.RegisterAsyncPostBackControl(Button1);
if (!IsPostBack)
{
Visibility = true;
}
UpdatePanel_1.Visible = !Visibility;
UpdatePanel_2.Visible = Visibility;
Visibility = !Visibility;
}
protected void Button1_Click(object sender, EventArgs e)
{
if (Panel1.Visible)
UpdatePanel_1.Update();
}
protected bool Visibility
{
get
{
return (bool)(ViewState["Visibility"] ?? true);
}
set
{
ViewState["Visibility"] = value;
}
}
The problem is that invisible controls aren't rendered to the client. So then trying to make them visible isn't going to work because as far as the client is concerned, they don't exist.
Try using style="display:none", or use different CSS classes and styles for visible and invisible panels, rather than setting visible=false;
You can invisible, or visible controls is child of updatepanel, not invisible, visible updatepanel, I try use updatemode = conditional but error, and then I visible controls add to updatepanel. Hopy help you
Thanks everybody post