I'm working on a .NET WebForm app which has a master page. The .NET can not recognize many elements in the aspx file. For example it say Label is not a valid asp element and then says most likely reason is a malformed web.config file.
I double check my web.config and all looks good. The other webpages do not have same issue. The interesting thing is I do not have this issue inside the MasterPage.
I also tried recreate the page from scratch but still having same issue.
I'm using VS2019. Framework 4.6
You have to provide some sample code and markup. Also, if you have a master page, then that is a huge deal also. As a general rule, asp.net controls you drop on the page are able to be used from code behind. However, the code for the standard page(s) that we use as a "child" of a master pages means that code behind for the master page can easy use controls in master page. And code behind for the page being displayed in that master page ALSO can freely use its own controls. But controls between the master page and the working child page is VERY different matter.
And of course controls dropped into a repeater, or say listview (or even gridview) means that the one label or text box control is automatic repeated over and over. As such, you have to pull/get/use the one row out of that data bound repeating control, and then from that one repeating row grab the control in question.
So, saying I can't start my car, or I can't use or get a control?
We need more information as to the context of what control, where it is (in the master or child), and is the control perhaps nested inside of a data bound repeater, listview, gridview etc.
so, edit your question - add some details as to the markup, where it is (master or the child page), and we can help.
So, as a general rule, code behind in master page is free to use controls in the master page.
And in the web page you created, once again code behind is free to use controls in that page.
It can be more difficult to say have code in master page, and have it reference controls in the child page that is being displayed. But, then again, it is VERY rare that code in master page would need to reference or play with controls in the child page, since a master page will (usually) just be your main navigation bar - and it will be the same for many if not all pages you display - hence you master page really can't know what controls will exist in the current child page being displayed.
Related
An interview question someone asked me but I was left stumped.
If you can implement user controls inside a normal aspx page, what is the use of a master page then ?
A master page defines a layout template. You put things like styling and scripts in the master page, then call them in any page derived from that master.
It's a way of being able to split presentation out from functionality, and things you need everywhere can be put in the masterpage.
I have two web-form pages in ASP, one for viewing a record and and another for editing it. I would like to have a link on each which popups a box to allow editing a certain property on the record. If I only placed it on the Edit page, I would use an UpdatePanel but I would have to copy and paste code if I wanted it on the View page as well. Is there a way to have the code in one area which be can be referenced and used from both pages?
Edit: I know I could make a custom control to handle it although it would include all its HTML on the page when the page first loads, not when the link is clicked.
Edit2: I wanted to avoid having the contents of the popup rendered when the page first loads but now I realize it's just a matter of not binding any data in it until the Postback occurs.
You can use a MasterPage for both the pages, and put the popup with UpdatePanel on the master page, so you can access it from both the pages.
Hope it helps.
Don't forget to upvote it if it solves you problem.
Thanks.. :)
Make the bulk of the panel a user control (ascx). Then just put a thin wrapper around it on both the pages where you need it. The bulk of the code is then in the ascx and ascx.vb and does not need to be written twice.
I have inherited a solution created in ASP.net with VB.net and am having a real problem with the error message "Content controls have to be top-level controls in a content page or a nested master page that references a master page."
The design is somewhat complex as follows:
The app uses a single Masterpage. The child page accessed has a custom user control on it. The user control contains, amongst other controls, an iframe. The source of the iframe is set programatically to another page, (aspx) which does not inherit from the Masterpage as we don't want the headers, footers etc. to appear in the iframe.
This aspx page has another custom user control on it that displays a small number of controls, buttons, text fields, file upload etc.)
This all works well in my IDE (Visual Studio 2005) and the file upload control is displayed properly. As soon as it's deployed to a server, (test or live) I get the error message at the beginning of this post.
The pages and code are too complex to post here but if I haven't given enough detail I will try to explain as necessary. I hope someone can help as this has been driving me insane. I've searched extensively with no success.
Many thanks.
We have a win application that shows a web form in a web browser.
In order to get data from this web form we are using a hidden text box and get its text using HtmlDocument object of web browser control.
I want to make an abstraction of this web form that has this text box element so that other forms can use this abstraction.
I made a web control and put the text box on it.I thought that if I put this control on my page it would have the text box.When i ran my application I noticed that the text box had been rendered but had its control name in its name (WebControl$TextBoxName) and its id(WebControl_TextBoxName) and the win app throw an exception since it couldn't find the element by its id(TextBoxName).
So here's my question:
How can I make an abstract web form/web control that has some elements on it and I can use it to make my final forms have these elements on them? (their names and ids should not be changed)
Thank you for your help
dotNet 4.0 supports static id's so they don't get mangled, read up on Client Id Mode
Alternatively, you could override the render of your control to output a standard html hidden form field with whatever ID you want, and then also add a custom property that will return the textbox that will hide the fact that it isn't an asp.net server control.
Though I've never used the browser control in WinForms, I think what you want to use is a Master Page. Assuming what you're rendering in the browser control is an ASPX page, create a Master Page with the hidden text box that you want to grab your data from, and tell all of the pages you want to have that common control on to use your Master Page. When the page renders, the control id will then be "ctl00_TextBoxName". There is no way of getting around the ID concatenation, since unique IDs are needed and that's the only way to guarantee uniqueness with all the nested control abilities of ASP.NET. However, doing this will guarantee you always have that control named the same on every new form you create that inherits the Master Page. Hope that helps!
In summary (because who reads paragraphs?):
Create Master Page
Place your common control in the Master Page
Have your Form inherit the Master Page
You can read up on how Master Pages work in MSDN's Documentation.
If they are different, under what circumstances should we decide to use either approach?
Also, what is the advantage of ascx over aspx?
user controls are a form of custom control, that gives you a visual designer. They are ideal for use when you want a reusable control within the same web site. (It is possible to create and package user controls as seperate assemblies but that is beyond the scope of this question and I know has been asked on SO).
A custom control is typically used to refer to a Web Control, or a Composite Control which is specialized form of a web control. These controls have no designer and are usually implemented in seperate projects from your web allowing them to be reused accross many sites.
Now your second question, ASCX and ASPX are two different things. ASCX is the extension for a User Control, where as ASPX is an ASP.Net Page. You cannot use an ASCX by itself it must be placed onto an ASPX or Master page.
One way I like to use user controls is I have for example a very complex page which have 7 tabs, 5 of those have grids, of those grids three of them are identicle. Well what I can do is create a seperate user control for the content of the tabs, this now reduces the code I need down significantly (Since three grids are identicle except for the data).
Further more it allows multiple to work on various parts of the page, and it helps me keep everything straight since I am reducing the complexity of the page. You do not use User Controls instead of Pages, you use them in conjuction with a page.
Edit
You do not use ascx over aspx. You use ascx to complement. For example on my site every page has the same footer, but I don't want every page to derive from a single master page. I can create my footer as an acsx control and put it in each of my master pages.
Another example, I have a form that lets a user enter three different date ranges. (And we have other forms). So I put the logic to enable a calender button, and a text box that when clicked on opens up the calender, in a user control. I can then reuse that user control in all my aspx pages.
Custom controls are control build entirely in code. The pro is that you can put them in libreries, add an icon to the toolbox and other fine control.
User controls are more easy to do, and in general is a way to encapsulate things to simplify other pages or when you need to use the same markup in several pages.
The advantage of controls over regular aspx pages is that you only need to do some part of the markup (not the whole page)
User Controls/Composite controls
User controls that are made up of other ASP.Net or custom controls. They are usually quite straight forward and can be created quite quickly. They Are generally not shared across projects however there are some tricks that can allow you to do this.
Custom controls
Custom controls are controls that you implement the UI by creating everything from the HTML output to design time support. Custom controls take much longer to make. You must use either Web.UI.Control or inherit from a sub control (Textbox for example). Custom controls are compiled to binary format to allow them to be distributed more easily. Since they are compiled they can be referenced from the toolbox in visual studio.
There are 2 main advantages to using a control in an aspx page. Encapsulation of logic and reuseability.