I'm sure this has a simple answer, but I can't find it. I need to create an ASP.NET control that doesn't render anything. This is similar to an ObjectDataSource that shows up as a gray box in the aspx design mode. Until now I have only created controls that DO render and I can't find what property, attribute, override, etc. will prevent rendering during design. Any pointers?
Edit: Just to clarify, by simply inheriting from Control, it renders [ TypeName "ControlId" ]. I want it to render as the gray box that says TypeName - ControlId.
OK well I played around with it and you're right, it's not trivial.
Turns out VS doesn't actually execute .ascx user control code when it's shown in the designer, it only parses the markup, so you can't conditionally change the control.
However, that limitation is not active when you use a real ASP.NET Server Control. Just add a new project to your solution of that type and in your .cs file, overrite RenderContents:
protected override void RenderContents(HtmlTextWriter output)
{
if (DesignMode)
output.Write("<table style='border-color:Black;background-color:Gray'><tr><td width=300px height=100px style='vertical-align:middle;text-align:center'>I'm your design time box.</td></tr></table>");
else
output.Write("Runtime text lalala");
}
Then in your .aspx file, you just add the control:
<body>
<form id="form1" runat="server">
<div>
<cc1:ServerControl1 ID="ServerControl1" runat="server" />
</div>
</form>
</body>
Design time result:
Run time result:
The property you are looking for is called DesignMode
Related
I have a div element in my HTML. I added a id and runat attributes to the element:
<div id="footer" runat="server">
After rendering, viewing the HTML shows:
<div id="ctl00_footer">
However, I cannot access it from the page's .aspx.cs code:
footer.InnerHtml += "test";
How do I access that element from the C# code?
you can use FindControl("footer"), and cast it to HtmlGenericControl.
HtmlGenericControl footer = (HtmlGenericControl)FindControl("footer")
One of the reasons can be that you don't have designer file for that page. So you can't access element by it's ID.
Just add class with name [your page name].aspx.designer.cs, open it, remove all code, save it, go to your view and click save - designer must generate code of all elements from your view. After this you can access element by ID.
There should be no problem accessing <div id="footer" runat="server"></div> the way you are doing. Strange though, my generated markup keeps the div id unchanged as footer.
Make sure you don't have any compile errors, and that you can access other elements running server-side in the same scope you are trying to access this div.
You need to set the ClientIDMode property of the page or control to Static:
http://msdn.microsoft.com/en-us/library/system.web.ui.control.clientidmode.aspx
This will prevent the "ctl00_" from being appended to the ID which is what is causing you the problem.
I have encountered this problem before. You may have the target div inside another div that does not have the runat="server" attribute. All nested divs should have the runat attribute in order to be able to access the inner elements.
<div id="divContainer" runat="Server">
<div id="yourDiv" runat="Server">
</div>
If you're going to code ASP.NET and you want to access the control from the server-side, you may as well use the provided controls.
Use a Panel instead of a Div. The ASP:Panel control renders as a div in the generated html anyway. The Panel doesn't have a .Text property, but you can add controls to it from code-behind (such as a Label or a LiteralControl.
Is there possibly a chance that the page was copy/pasted when being created? If so, make absolutely sure that all references to the old page are changed to the name of the new page. I've done this before within the code at the top of the ASPX page, as well as the namespace of the designer page.
I had the same problem and found out that due to a "copy" and "paste" my function had a "static" declaration.
Removed it since static functions can't access non-static identifiers and it was fixed.
I have the same issue.
My solution was to have 'ID' instead of 'id' for the div element (i.e. the casing was the reason).
When don't you need to use runat="server" in ASP.NET?
EDIT: Thanks for all the answers, but I was really thinking of runat="server" inside an <asp: tag.
Use the runat=server attribute when you're using ASP.NET controls, and/or you require programmatic access to those controls in your code-behind.
HTML controls don't require this attribute. It's useful if you have any HTML element like <span> <div>, or <table> when you want the ability to access them in code-behind.
<asp:Label runat="server" id="foo" />
<div runat="server" id="bar />
...
foo.Text = "Hello Label";
foo.Attributes["class"] = "baz";
You need to use runat="server" on any control that you want to be parsed as a server control.
Any element with runat="server" will be parsed into a server control in the Page herarchy. Anything else will be handled as plain text, and put in LiteralControl controls in the Page hierarchy.
The exception is elements that aren't real elements, but special tags within another server tag, for example ContentTemplate tags. They don't need a runat="server" because the containing control will parse them.
When you don't want the server side ASP.NET to render a server side variable against us.
Generally speaking you don't use it when you don't need to manipulate the DOM element at the server side e.g. which are only used for layout purposes.
Without runat="server" there would also be no other way to make html controls server side controls. It does look like an odd thing, because you can't do runat="client".
So in summation you can't leave it out on any ASP .Net controls ever and it was probably the easiets and cleanest way to find all server side controls for the developers who created ASP .Net Web forms.
source: http://mikeschinkel.com/blog/whyrunatserverforaspnetpart2/
Tag runat="server" indicates that the code contained within the script block will run on the server (and not on the client). On execution, ASP.NET will create server-side objects that contain this code as well as an instance of the Page class to contain the controls defined inside the page as instances of their given type (System.Web.UI.WebControls.Textbox, for example). This server-side object will be invoked on user request and will execute code in response to events.
Create Control in Runtime
I need one label in runtime that time don't need runat="Server" is not required
Example
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
Label lblNew = new Label();
lblNew.ID ="lblnew";
lblNew.Text ="Test";
}
}
this code create label in runtime at page load event
I have an ASP.Net web site and on one of the pages I'm using a repeater to render several iterations of a UserControl, that UserControl contains a second UserContol that has two text boxes that my User must enter information into. I want to be able to have my user push a button and add another instance of the second UserControl (with the two textboxes) to my original UserControl, so that the user has 4 textboxes displayed on the screen for the first UserControl. The problem I am seeing if I try to add the second UserControl to a given iteration of the first, is that the page postback causes any other of these second user controls to be deleted from the page.
Does anyone know of a way to do this using JQuery? I've had three posts that describe how to solve this problem using server side dynamic controls, and/or AJAX, but we've decided to focus on a JQuery solution because this server side mechanism is too costly in terms of resources for us.
I've been working on the suggestion by Zincorp below, and now have the JQuery working to clone a textbox, but having trouble using the server side Request.Form collection to iterate over the controls. Can anyone give adivce on how to iterate over the Request.Form collection?
OK, I think the problem with iterating over the controls using the Request.Form.AllKeys collection turned out to be that I was using an HTML Textbox, rather than an ASP TextBox Control. Apparently the Request.Forms.AllKeys collection only contains ASP controls, not HTML controls.
The problem I am seeing now is that when I clone the control in JQuery, and then submit my page with the submit button, the 2 controls have the same ID, and so are combined (I think) by http into one ASP TextBox Controls containing both values, with a comma delimiter (e.g.- 40,20). Anyone know how to get a new ID assigned to the cloned ASP TextBox?
Here is the updated markup in a sample ASP.Net web appliction:
<%# Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Label runat="server" ID="ProjectDisplay" Text="Project" />
<asp:TextBox ID="ProjectValue" runat="server" ></asp:TextBox>
<div id="mydiv" ></div>
<br />
<br />
<br />
<input id="AddProject" type="button" value="Add Project" />
<br />
<br />
<asp:Button ID="Submit" runat="server" Text="Submit" onclick="Submit_Click" />
</div>
</form>
</body>
</html>
<script language="jquery" src="js/jquery-1.3.2.js" type="text/javascript"></script>
<script type="text/javascript" >
$(document).ready(function() {
$("#AddProject").click(function() {
var x = $("#ProjectValue").clone();
x.appendTo("#mydiv");
});
});
</script>
And here is the updated server side code where I'm trying to iterated over items in the Request.Form collection to get information from it:
public partial class _Default : System.Web.UI.Page
{
protected void Submit_Click(object sender, EventArgs e)
{
foreach (string s in Request.Form.Keys)
{
object x = Request.Form[s];
}
}
}
Before choosing a solution for the problem, consider the problem first:
You effectively need to:
1) Duplicate controls/markup on the client-side
2) Obtain these values on the server-side on a postback
3) For each of the added "user controls" on the client-side, add them as children of the first user control on the server side.
I'm not going to give the code, but here are some ideas:
1) Use jQuery's .clone() method (http://api.jquery.com/clone/) to duplicate the markup being rendered by the usercontrol containing the textboxes. Perhaps wrap them in a div without runat="server" to so that you can easily obtain it by ID. You'll probably need to then recursively iterate through the children in the cloned element and append a # to them to avoid any conflicting identifiers. (eg. nameTextBox_1, nameTextBox_2, etc.)
2) On a postback, use the Request.Form collection on the server side to obtain the textbox values. Iterate through it and snag all of the items whose keys start with "nameTextBox_".
3) For each added "user control" on the client side, create the actual user control on the server side, assign to it the values entered in the textboxes, and then add it to the child controls of the first one. This way the state is maintained upon returning to the user.
The short answer is that you would have to add the controls before the ViewState is initialized.
The video on this site has a nice guide on adding dynamic controls. http://www.asp.net/%28S%28wnmvzu45umnszm455c1qs522%29%29/learn/ajax-videos/video-286.aspx
This is probably not a ViewState issue. That may be the first place to look, but after that you need to make sure that your dynamic controls are actually being CREATED on each load.
Generally speaking, the ViewState is only responsible for restoring STATE to existing controls (hence the name). It is not responsible for recreating controls.
I believe you are experiencing a viewstate problem. Your dynamic controls are not being persisted. If you haven't already, read Dave Reed's excellent article Truly Understanding Viewstate. Pay particular attention to the section "5. Initializing dynamically created controls programmatically" which applies to the trouble you are experiencing.
I have a web application that has a page that loads the content from the database. I want to be able to put a form in the dynamic content, but .net doesn't let the inside form perform it's action. Is there a way to allow this or some other way I can get a form on a dynamic content page?
--EDIT--
I think I need to clarify something. This is an aspx page that loads content from the database. As far as I know, the text I pull from the db and stick in the Label is never compiled or processed by the .net wp, thus I can't use the code behind to fix this issue.
This is a common problem, when you want to have a non-postback form to a 3rd party site (like a PayPal button, for example).
The problem occurs because HTML doesn't let you have form within a form, and most ASP.NET pages have a <form runat="server" /> "high up" in the HTML (or in the Master page).
My favorite solution is to hide the "high up" form tag, while still showing all of the content. Then you can feel free to dump any tags you want in the body. If you do this dynamically you can choose on a page-by-page basis which pages have custom forms.
I created a class called GhostForm.cs to handle this. You can read all about it here:
http://jerschneid.blogspot.com/2007/03/hide-form-tag-but-leave-content.html
There can only be one form on the page (the asp form); you have to use that form somehow.
To clarify, there can only be one form processed.
Not with webforms, no. You have to work within the one, full page form by using an event handler connected to a Button to LinkButton. Fortunately, it's pretty easy to do:
foo.aspx:
...
<asp:TextBox id="txtFoo" runat="server" />
<asp:Button id="btnFoo" runat="server" onclick="btnFoo_Click />
...
foo.aspx.cs:
...
protected void btnFoo_Click(object sender, EventArgs e)
{
string s = txtFoo.Text;
// do something with s
}
...
Dino Esposito has an article from MSDN magazine that covers handling multiple forms or "simulating" sub forms in ASP.Net that might just answer all your questions.
http://msdn.microsoft.com/en-us/magazine/cc164151.aspx
Any work around would be hacky and very ugly. By design asp.net uses a form tag to post and get data. This is why they call it a Web Forms Application. Html does not allow nested forms. What you want to do is use a WebRequest in your code behind.
If you are trying something like a paypal button you could simply use something like this.
Markup:
<div id="PayPalButtonContainer" runat="server"></div>
Code Behind:
public static string GetPayPalButtonMarkup()
{
const string markup = #"https://www.paypal.com/cgi-bin/webscr
?cmd=_xclick&business={0}
&item_name=Widget
&amount={1}
¤cy_code=USD";
return markup;
}
PayPalButtonContainer.InnerHtml = string.format(GetPayPalButtonMarkup,"YOUR PAYPAL USER NAME", "YOUR PRICE VALUE");
you either have to deal with the postback by adding a server side click event handler to what you want to be the "sub forms" submit button (this is how web formas deals with multiple submit type buutons on the same page) or do soemthing clever with AJAX if you dont want a full post back
I've run across this issue before. One workaround that I have done is to place my code that I want my action to be done upon inside of an asp:Panel. With the panel you can set the attribute of "DefaultButton" to a button inside of the panel, and clicking the button (or pressing "enter") will fire that button's click event. I've found this quite handy when wanting to submit a "form" by pressing enter when I have a master page that contains the only allowable asp:Form.
Hope this helps.
When I first came across this problem, I found the simplest solution for me was to simple COPY and PASTE the Master page and give it a slightly different name, something like:
SiteNameMasterPage 'Default page with FORM tag
SiteNameMasterPageNF 'No Form tag
And then depending on wether I wanted a FORM tag or or not, simply change the masterpage link at the top of my CONTENT-PAGES, like this
<%# Page Title="" Language="VB" MasterPageFile="~/SiteName.master" %>
<%# MasterType VirtualPath="~/SiteName.master" %>
<!-- This masterpage has the default FORM tag -->
or
<%# Page Title="" Language="VB" MasterPageFile="~/SiteNameNF.master" %>
<%# MasterType VirtualPath="~/SiteNameNF.master" %>
<!-- This masterpage does NOT have the default FORM tag -->
and then in the content page, wherever I want to place my form I can include the <form> tag
For example, I have a custom control called SampleControl. To simplify things for this question, pretend I'm making just a Panel Control clone from scratch.
<CC:SampleControl ID="Sample1" runat="server">
<asp:Label ID="Label1" runat="server" Text="Hi"></asp:Label>
<asp:Button ID="Button1" runat="server" Text="Button1"></asp:Label>
</CC:SampleControl>
To Output:
<div id="Sample1">
<span id=Label1>Hi</span>
etc.....
</div>
Where the Code is:
public class SampleControl: WebControl
{
.....Render Stuff Goes Here.....
}
The ASP controls in the middle aren't being registered by ASP.NET. When I did a Reflector on the Panel control, I couldn't find out how they got the middle controls to render. It doesn't look like they are using a Templated Control.
When I do it, I get this error:
Parser Error
Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately.
Any Ideas?
First, [ParseChildren(false)] attributes lets parser know that you want your control to treat nested content as child controls.
Then make sure that somewhere in Render the RenderChildren method is called. It's the default implementation of System.Web.UI.Control.Render(), so you can do base.Render(writer) in your overriden Render method.