In Asp.net Web forms why must a user control be partial? I tried to remove the partial keyword and it says:
Missing partial modifier on
declaration of type 'test'; another
partial declaration of this type
exists
Where is the other declaration?
I am trying to pass a generic type with the user control how can I do that? I can't unless I change the other declaration too. I couldn't find it so I removed the partial keyword.
Note:
you do have 3 files if your making WebApplication but if your making website you only get 2 files !
UserControl.ascx
UserControl.ascx.cs
so in website where is the other declaration ?
the reason i want generic is because im making a Grid User Control so i want to pass the type the datasource is going to have.
ASP.NET uses partial classes for the codehind because it has to generate all the server side controls you have declared in your ASPX file to a class and merge all the other data files that come along with your codebind. It allow the classes ASP.NET uses to be distributed across multiple files.
From MSDN:
The code file contains a partial
class—that is, a class declaration
with the keyword partial (Partial in
Visual Basic) indicating that it
contains only some of the total code
that makes up the full class for the
page. In the partial class, you add
the code that your application
requires for the page.
This is the key part:
When the page is compiled, ASP.NET
generates a partial class based on the
.aspx file; this class is a partial
class of the code-behind class file.
The generated partial class file
contains declarations for the page's
controls. This partial class enables
your code-behind file to be used as
part of a complete class without
requiring you to declare the controls
explicitly.
What are you trying to do by adding a generic type to a user control? Can you accomplish this by adding a Type property to the UserControl and then using that?
They have to be partial because the designer autogenerates the stuff you do in the Design window. Usually that code is in the foo.designer.cs (or whatever the extension for an asp.net form is). If you want to change the class, you have to generate the UI manually without the designer or use the designer and copy the code over to your proper class.
There are actually three files for each user control.
UserControl.ascx
UserControl.cs
UserControl.designer.cs
The designer file has a partial implementation because of that your code behind also has to be partial.
They don't have to be partial, indeed I've never used a partial class for one. Some of the code-generation tools will use partial so that they can more readily alter bits based on GUI-work you do without you and it getting in each others way, but that's for the tools rather than for the code.
Related
In my master page I will load some data from the database. I have place it into an asynchronous method. For normal pages I place Async="true" on the top but if I do it on the master page, I have the following error:
myproject.master does not contain a definition for AsyncMode and blablabla...
I've also search on the internet but nothing found for an asynchronous master page. Language I use on background is C#.
Can anyone help me?
The sample uses the new async and await keywords (available in .NET 4.5 and Visual Studio 2012) to let the compiler be responsible for maintaining the complicated transformations necessary for asynchronous programming. The compiler lets you write code using the C#'s synchronous control flow constructs and the compiler automatically applies the transformations necessary to use callbacks in order to avoid blocking threads.
ASP.NET asynchronous pages must include the Page directive with the Async attribute set to "true".
Master File contain master directive.
Master Page inherit MasterPage class of System.Web.UI which does not contain AsyncMode property..So you can't use it at master page.
Normal Page inherit Page class of System.Web.UI which contain AsyncMode.
You can set it in the master page like this. Found solution here:
public abstract class MyBasePage : System.Web.UI.Page
{
public MyBasePage()
{
this.AsyncMode = true;
}
}
Then change the inheritance in the aspx.cs file to something like this:
public partial class WebForm1 : MyBasePage
It can break the system when you set the AsyncMode property in anything else then the constructor.
My problem is to make a code behind file of an aspx i.e already existing 1.aspx pages aspx.cs
to be available to another page aspx with out replicating any of the code in code behind.
i.e 1.aspx --> code file is 1.aspx.cs.
now 2.aspx --> code file is 1.aspx.cs
under the condition that the controls used in both aspx pages have identical Ids
Honestly, if you have such requirement, you should better encapsulate common behavior either in a base class that can be inherited by the two page's dedicated class, or create utility/business class that contains the code.
You should also consider using User Controls. This can help you to create reusable visual component in your application.
Im trying to extend repeater control to add pagination. I started with creating control which derives from Repeater but there is a problem:
public partial class controls_pagination : Repeater
Compiler Error Message: ASPNET: Make sure that the class defined in this code file matches the 'inherits' attribute, and that it extends the correct base class (e.g. Page or UserControl).
That should I do to make it work ?
You can paging repeater using this code. please go through the link :
http://www.codeproject.com/KB/custom-controls/CollectionPager.aspx
http://www.codeproject.com/KB/webforms/SQLPager_For_Everything.aspx
I have a ASP.Net project that is setup in such a way that it can be dropped into any site and "just work." All the paths are relative to the current file, not relative to the "~". The paths are determined by ThePath = this.TemplateSourceDirectory;
This is working for everything expect registering a custom control that is created and added to one of the pages. I can add the control just fine with the Page.LoadControl but I cant cast it as the correct type to access anything.
How can I add a reference to the class from within the code itself?
If you don't know the control's specific type ahead of time, this isn't possible. The class must derive from UserControl, so you can cast it to a UserControl and you'll have access to all the methods and properties on that class. If there's some special information or functionality you need to require all controls to have, and you need to be able to assume those are always present, then you will have to write your own class that derives from UserControl, and require all custom controls to derive from that instead:
//all custom controls must inherit from this
public abstract class SpecialControlBase : UserControl
{
public abstract void DoSomethingSpecial();
}
Then you could cast all controls at load-time to this SpecialControlBase, and have access to the DoSomethingSpecial method.
But as far as the most-specific members of a class loaded at runtime, think about it - if I write my own control called RexsUserControl and drop it into your application, there's no way you could know what methods and fields I've put on my control, so you can't write any code that references those members specifically.
Rex M, If you register the control on the ASPX page, you can cast the control on the code behind.
In the ASPX:
<%# Register TagPrefix="Mine" TagName="Ctrl" Src="~/Test/User/Controls/UserCtrl.ascx" %>
Then, in the ASPX.CS:
User_Controls_UserCtrl myUserCtrl = LoadControl("~/Test/User/Controls/UserCtrl.ascx");
however, if you don't register the control in the ASPX first, you get this error:
CS0246: The type or namespace name 'User_Controls_UserCtrl' could not be found (are you missing a using directive or an assembly reference?)
I have a problem (obviously the question :)
I have a project-- MyProject... hence the rest of the project uses a default of any classes as namespace "MyProject"... no problem.
In my project, I created a custom user control that has many other controls on it (label, textboxes, etc). So, that class is ALSO within the default namespace of "MyProject". All compiles no problem. Just to confirm scope visibility, on this user control, I made sure that the DESIGNER code and the Code-Behind (My code) are BOTH within the same "MyProject" namespace (they are), AND they are both respectively PUBLIC PARTIAL CLASS MyUserControl.
Now the issue. I create a simple form (also in namespace "MyProject" by default). From the toolbox, the "MyUserControl" exists so I drag it onto MyNewForm. Drag/Drop is fine.
Save all, compile, fail... The Designer is adding an extra "MyProject" reference thus making it appear that the user control is actually located at MyProject.MyProject.MyUserControl .. instead of MyProject.MyUserControl.
As soon as I manually remove the extra "MyProject.", save and compile, all is fine. However, if I re-edit the form, change something, M$ changes it back to the original "MyProject.MyUserControl" reference.
All that being said, here are the snippets from my project...
namespace MyProject
{
partial class MyNewForm
{
...
private void InitializeComponent()
{
// THIS is the line that has the extra "MyProject." reference
// when I manually remove it, all works perfectly
this.MyUserControl1 = new MyProject.MyUserControl();
}
}
private MyUserControl MyUserControl1;
}
Then, in the MyUserControl definition I have...
namespace MyProject
{
public partial class MyUserControl : UserControl
...
}
and from the MyUserControl via the Designer...
namespace MyProject
{
public partial class MyUserControl : UserControl
...
}
Thanks for the help...
What the designer is doing is ok.
--> You have somehere in your project a namespace called MyProject.MyProject.
(Try finding it in "Class View")
PS. to anyone who has same problem but has not found any solution...
Assuming you have created a new WindowsFormApplication;
Create a new WindowsFormApplication project using same name as its solution name.
The default pre-created Form name comes called "Form1". And change its name same as the project name.
Add new UserControl class into the project.
Build/Rebuild the project and check the usercontrol is located at Toolbox.
Drag the usercontrol onto the form and start debugging.
Error: The type name 'userControlName' does not exist in the type 'projectName.FormName'
I had research on net for any solution but couldn't come up with any answer...
But if you change the form name any other different from the project name, it'll be resolved.
If you insist on that the form name and project name has to be same depending on your project needs, a custom DLL could be created and use the usercontrol in it.
Then to use as a control, add the DLL file to "ToolBox" using "Choose Items..."
Finally it is going to be ready to use.
PS2. struggling the same problem for hours, this is the solution I found.
The Namespace Name and Class Name need to be different. The code generated by adding the WCF automatically references the Namespace but if the Class name is the same as the Namespace name, the generated code looks at the Class and nothing will compile.
Name of User Control and Form are same. Using different names will solve the issue.
Since this was a top search result when I had this error, just want to post my cause and solution.
I had two projects within a solution, sharing a 'common' class file which was added as a link.
I added a second 'helper' class file as a link, used its code within the first, and got the error.
The problem was I had not added the second 'helper' class as a link in both projects.
So the other project had an updated 'common' class, but no knowledge of the 'helper' class it now used.
Note to self: pay more attention to the project column of the error list :)
Just encountered this where I had a MasterPage that had an explicit
<%# Import Namespace="MyNamespace" %>
in the .master file
This also happens when you use different pages but with same name. In my case I had created "Grants.xsd" dataset and "Grants.aspx" page. Somehow they got in conflict resulting in this error.
You can easily trouble shoot this by hovering over the culprit keyword (class name) and in Visual Studio 2013, it will tell you exactly where the conflict is.