I have an error in a content placeholder. When I try to create a master page it shows me an error as below in the master page and I can't see any items such as buttons, labels, etc. inside the .aspx pages.
Also I can't add content placeholder from the VS Toolbox, it shows a cross mark on the Content placeholder button.
{ Error Rendering Control - ContentPlaceHolder1
An unhandled exception has occurred.
This control can only be used in a MaserPage.}
ASP.NET master pages allow you to create a consistent layout for the pages in your application. A single master page defines the look and feel and standard behavior that you want for all of the pages (or a group of pages) in your application.
In addition to static text and controls that will appear on all pages, the master page also includes one or more ContentPlaceHolder controls. These placeholder controls define regions where replaceable content will appear. In turn, the replaceable content is defined in content pages. Here is an example of a master page
<%# Master Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML
1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server" >
<title>Master page title</title>
</head>
<body>
<form id="form1" runat="server">
<table>
<tr>
<td><asp:contentplaceholder id="Main" runat="server" /></td>
<td><asp:contentplaceholder id="Footer" runat="server" /></td>
</tr>
</table>
</form>
</body>
</html>
Here should be a content page looking like
<% # Page Language="C#" MasterPageFile="~/Master.master" Title="Content Page 1" %>
<asp:Content ID="Content1" ContentPlaceHolderID="Main" Runat="Server">
Main content.
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="Footer" Runat="Server" >
Footer content.
</asp:content>
please read more here about ASP.NET Master Pages
VERY very basic question. I'm trying to learn ASP.NET. I created a default website1 in VS 2013 Community I get a ton of files. When I run the app in IS, the default.aspx web page appears and all is OK, but above the web page is a banner with links to contact.aspx, login.aspx. register.aspx, etc. and I cannot find where that banner is? It's not on default.aspx. Where is it? Seaching the project for "Contact.aspx" only returns one result, the page itself, as an example.
It's probably coming from a Master Page. Look at the <%# Page %> header at the tops of the .aspx files. You'll see they reference a master page. A Master Page is used to provide structure to the site. It means you don't have to write the same HTML for common elements on every single content page. Content pages (.aspx) then can have their content inserted into the Master Page. And yes, you can nest master pages. This is all done through the <asp:ContentPlaceHolder /> (higher level Master Page) and <asp:Content /> (nested Master Page or Content Page) tags.
Let's look at an example:
MasterPage.master
<%# Master Language="C#" %>
<!DOCTYPE html>
<html>
<head runat="server" >
<title>Master page title</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ContentPlaceHolder id="Main" runat="server" />
</div>
<div>
<asp:ContentPlaceHolder id="Footer" runat="server" />
</div>
</form>
</body>
</html>
Default.aspx
<%# Page Language="C#" MasterPageFile="~/MasterPage.master" Title="Content Page 1" %>
<asp:Content ID="Content1" ContentPlaceHolderID="Main" Runat="Server">
Main content here.
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="Footer" runat="Server" >
Footer content here.
</asp:Content>
The resulting HTML will look like this on the client when you access Default.aspx:
<!DOCTYPE html>
<html>
<head>
<title>Content Page 1</title>
</head>
<body>
<form id="ContentPage_form1">
<div>
Main content here.
</div>
<div>
Footer content here.
</div>
</form>
</body>
</html>
Take special note of how the ID of the form changed from the server side to the client. This trips a lot of people up when they start doing client side JavaScript. If you want the ID to not change, you have to add the ClientIDMode="Static" attribute to the control (you can also set it at page, web.config, or machine.config levels).
Given the following code below. How might I display another web page or content within the placeholder via a server onClick event in C# code; similar to now defunct iframe. I perfer to handle all events via sever side code (C#, asp.net 4.0)
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server"></asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContentPlaceHolder"
runat="Server">
<asp:PlaceHolder runat="server" ID="PlaceHolder1">
</asp:PlaceHolder>
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="NavigationContentPlaceHolder" Runat="Server">
<uc1:NavigationUserControl runat="server" ID="NavigationUserControl" />
</asp:Content>
Thank you in advance!
You can use WebClient to receive a page from a URI. (It can also send content to a URI too.)
<asp:Button runat="server" ID="Button1" OnClick="Button1_Click"
Text="Load Page"/>
<asp:PlaceHolder runat="server" ID="PlaceHolder1">
</asp:PlaceHolder>
protected void Button1_Click(object sender, EventArgs e)
{
var uri = new Uri("http://www.stackoverflow.com");
var result = new WebClient().DownloadString(uri);
PlaceHolder1.Controls.Add(new LiteralControl(result));
}
I've created very simple web site for the test purposes. Only one master page and one content page.
My content page looks like this:
<%# Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" Title="Untitled Page" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<div id="TestDiv1">bla bla</div>
<div id="TestDiv2">ble ble</div>
</asp:Content>
Now, based on some condition I would like to show/hide a given div. So I am trying to reach one of those divs by Controls collection, like this:
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
ContentPlaceHolder myContent = (ContentPlaceHolder)this.Master.FindControl("ContentPlaceHolder1");
myContent.FindControl("TestDiv1").Visible = false; //this is not working
}
}
}
}
But the above example is not working. None of the two div control exists in the myContent.Controls collection. If I place for example a TextBox on my content page, I can reach it through Controls.
So what should I do to be able to access the div control?
your divs are HTMLcontrols, try to add them the tag runat="server"
<div id="TestDiv1" runat="server">bla bla</div>
That should solve your issue.
You need to set runat="server" on the divs.
I'm very new to ASP.NET, help me please understand MasterPages conception more.
I have Site.master with common header data (css, meta, etc), center form (blank) and footer (copyright info, contact us link, etc).
<%# Master Language="C#" AutoEventWireup="true" CodeFile="Site.master.cs" Inherits="_SiteMaster" %>
<!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 id="tagHead" runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" href="styles.css" type="text/css" />
</head>
<body>
<form id="frmMaster" runat="server">
<div>
<asp:ContentPlaceHolder ID="holderForm" runat="server"></asp:ContentPlaceHolder>
<asp:ContentPlaceHolder ID="holderFooter" runat="server">Some footer here</asp:ContentPlaceHolder>
</div>
</form>
</body>
</html>
and I want to use second master page for a project into sub directory, which would contains SQL query on Page_Load for logging (it isn't necessary for whole site).
<%# Master Language="C#" AutoEventWireup="true" CodeFile="Project.master.cs" Inherits="_ProjectMaster" MasterPageFile="~/Site.master" %>
<asp:Content ContentPlaceHolderID="holderForm" runat="server">
<asp:ContentPlaceHolder ID="holderForm" runat="server" EnableViewState="true"></asp:ContentPlaceHolder>
</asp:Content>
<asp:Content ContentPlaceHolderID="holderFooter" runat="server">
<asp:ContentPlaceHolder ID="holderFooter" runat="server" EnableViewState="true"></asp:ContentPlaceHolder>
</asp:Content>
But I have a problem: footer isn't displayed.
Where is my mistake? Am I right to use second master page as super class for logging?
Project page looks like this:
<%# Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" MasterPageFile="~/Project.master" %>
<asp:Content ContentPlaceHolderID="holderForm" runat="server">
<p>Hello World!</p>
</asp:Content>
<asp:Content ContentPlaceHolderID="holderFooter" runat="Server">
Some footer content
</asp:Content>
I've been working with nested master pages and have run in to something similar. From what I see where you have "Some footer here" in the Site.Master is where the problem lies and I've had similar problems with having content with-in a contentplaceholder tag. if you try this instead
<asp:ContentPlaceHolder ID="holderFooter" runat="server"/>Some footer here
Then you should be able to see the footer content.
I'm not sure I'd use master pages for this. If it's really just going to do logging, I'd implement IHttpModule, register it in web.config, and then check whether or not to log based on the path of the request. I think of master pages as being about content rather than other processing such as logging.
See the IHttpModule walkthrough on MSDN for an example - in your BeginRequest handler, you'd probably check the request path and log appropriately if it matched.
Apologies if I misunderstood what you're trying to do though.
You should leave your ContentPlaceHolder empty, for it gets substituted by the content of the Content in your actual Page...
When you move the "Some footer here" text to your Content, you will see your lines of text :)
HTH
This link gives a simple explanation on Master pages,
http://waxtadpole.wordpress.com/2009/01/16/master-page-content-not-visible-visual-studio-2008/
The question are you right to use child Master pages in this instance - I would say master pages should be helping you solve issues around building a consistent layout, not for whether or not logging should occur.
The problem is, when the text elements placed inside Default.aspx are put in their relative Content Placeholders, they are written on the placeholders of your Site.master page and not those of Project.master (which have the same names).
You should resolve the naming conflict, by assigning different ContentPlaceHolderIDs to the the placeholders in Project.master (this means you'll also have to change the references in Default.aspx).
This would be your Project.master file:
<%# Master Language="C#" AutoEventWireup="true" CodeFile="Project.master.cs" Inherits="_ProjectMaster" MasterPageFile="~/Site.master" %>
<asp:Content ContentPlaceHolderID="holderForm" runat="server">
<!-- whatever... -->
<asp:ContentPlaceHolder ID="holderFormInternal" runat="server" EnableViewState="true"></asp:ContentPlaceHolder>
<!-- ... -->
</asp:Content>
<asp:Content ContentPlaceHolderID="holderFooter" runat="server">
<asp:ContentPlaceHolder ID="holderFooterInternal" runat="server" EnableViewState="true"></asp:ContentPlaceHolder>
</asp:Content>
And thus, your .aspx pages that use the Project master page instead of the global Page.master must be changed to:
<%# Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" MasterPageFile="~/Project.master" %>
<asp:Content ContentPlaceHolderID="holderFormInternal" runat="server">
<p>Hello World!</p>
</asp:Content>
<asp:Content ContentPlaceHolderID="holderFooterInternal" runat="Server">
</asp:Content>
If the only reason is to implement loggin why would you mess around with masterpages?
If the logging isent supposed to display any text!?
You either do as Skeet proposed with an IHTTP handler.. Or lazier one would be do have a class that derives from webpage and implement logging in that class and make your pages that need logging dervice from that..
ex:
public class LoggingPage : : System.Web.UI.Page
{
public override void OnLoad()
{
// Do logging
}
}
partial class OneOfTheWebPages : LoggingPage
{
public void onLoad()
{
base.onLoad();
}
}
I may be misunderstanding your problem - but from the code you've posted, there isn't anything in the footer.
In your Project page, the <asp:Content> tag for the holderFooter content place holder doesn't have anything in it.
I have next inheritance tree:
Site.master <-- Page1.aspx
<-- Project.master <-- Page2.aspx
And I don't know why Page2 display only content of itself and it's master page - Project. But doesn't display a content of Site (as Page1 does) Why? What have I to write for doing that?