I have the following classes in my vb.net application:
Form1
Usercontrol1
LnkLabel
Usercontrol1 is a user control , and doesnt contain any extra code. LnkLabel is a class that inherits Forms.Label. Its code is goven below:
Public class LnkLabel
Inherits Label
Sub clk handles me.click
Process.start(text)
End sub
End class
When I add an Instance of LnkLabel to usercontrol1, i get an error "type LnkLabel is not defined"
There are three instances of the error in uc1.designer.vb.How can I solve these Errors?
Note:
Visual Studio 2010
.Net FW 3.5
Edit:
The usercontrol1 donot contain any code that might be causing the error. It is just a new usercontrol added to the project.
LnkLabel is added to UC1 by the designer, not by using code at runtime.
The class name is LnkLabel, and not "LinkLabel".
I find that the easiest way to resolve this type of issue is to open the Designer.vb file directly.
To do this, choose Show All Files from the Project menu, then expand UserControl2. Double-click on the UserControl2.Designer.vb file.
You should also be able to get there by double-clicking on the error in the compile errors list.
Once there, search for the definition of UserControl1 or uc1, whatever it may be called (ensure you are in the type definition area, not the property assignment area).
Looking at the definition may give you an instant clue as to the problem (is it in the wrong namespace; did the name of the user control change after you created it, but the change was not propagated to this form; etc).
If it is not obvious what the issue is, use VS intellisense to help you get the right class. I usually clear the previous type definition and start typing the name I know it should be (i.e. UserControl), then select the appropriate value from Intellisense.
Selecting a different class (or correcting the class selection) will require a change to the control instatiation code and may also require a change to some of the properties (I usually just remove the properties I am unsure of and update the control directly in the designer).
Before you switch back to the designer, ensure that you save your changes and, if possible, compile the app.
Related
My vb.net program was functioning properly. After I renamed Form1 in the code pane of Visual Studio 2015 the Program.vb[Design] pane will not open and the following message appears:
The class Form1 can be designed, but is not the first class in the file. Visual Studio requires that designers use the first class in the file. Move the class code so that it is the first class in the file and try loading the designer again.
The name change was in the first class (form) so I cannot move it further up.
Before the change there were no errors. After the change there are many handles clause, variable not declared and not a member of errors.
I had 2 choices for Startup form in the Application tab of My Project before the change. After I have only 1 choice from a dropdown list. Both choices were Class names.
Is there anything I can do to recover the Designer view? Should I just recreate the form?
Thanks in advance, for any suggestions.
Okay, in Visual Studio 2012 I have a VB.NET project with originally two forms. Form1 was originally set as the startup form and then obsoleted. Form2 is a nearly identical form that has all of the new desirable functionality.
In my project's settings, Form2 doesn't appear as an available option for Startup Form. (Though it is a normally-created form that inherits Form) After some "troubleshooting," Form1 has been deleted, resulting in the the "Enable Application Framework" option being disabled and no Startup Object being available. When I select anything from the Startup Object drop-down, either Sub Main or Form2, I have an error message stating either "Sub Main not found in Solution" or "Form2 is a type in Solution and cannot be used as an expression" respectively. If I try to enable "Enable Application Framework," I receive an error popup stating "Startup object must be a form when 'Enable application framework' is checked." And Application.Designer.vb is empty.
Some things I've tried:
Clean and Rebuild Solution
Restarting Visual Studio
Temporarily deleting Form1 (it's still excluded from project)
Added a new form, per Neolisk's advice. It appeared in the available objects. I selected it and turned on application framework. From here, I copied the initialization code from Form2's designer code into Form3's. All was alright. Then, I copied Form2's main code into Form3. Now, "Form3 is a type in Solution and cannot be used as an expression" appears in my error list.
With that said, my question is how can I get Visual Studio to recognize my form as a form and set Form2 as the startup object?
add InitializeComponent() in new() function in form2
Found it! The issue was an overload of the form's constructor taking a form as a parameter. Since this was the only constructor in the file, I guess it caused confusion. Commented that out and all was right with the world again.
Sometimes you have a different class name from the form file name.
Check if the class name is listed.
I am trying to create a UserControl in VB.net, under VS2010. I have the code for the UserControl and I would like to add it to a form. My problem is that, according to every book and forum I have seen, after I build the UserControl, it should show up in the Toolbox. It doesn't. I even downloaded code from a book, the code executes perfectly, but their TrafficLight control doesn't go in the Toolbox (even though the book says it should - and that the only way to set its properties and to add it to the form is through the Control properties). I have tried to add the control to the form manually, by declaring it
Dim myObj As New SomeClass.SomeControl
and in the Designer.vb, identical with the buttons on the form:
Friend WithEvents myObj As SomeClass.SomeControl
With both, I get an error saying
'myObj' is already declared as 'Friend WithEvents myObj As SomeControl' in this class.
And either way, I get an error when I try to look at the design:
Could not find type 'SomeClass.SomeControl'. Please make sure that the assembly that contains this type is referenced. If this type is part of your development project, make sure the project has been successfully built using settings for your current platform or AnyCPU.
The control by itself builds and shows up in design view (not in the Toolbox though, even though it Imports System.ComponentModel and Inherits System.Windows.Forms.UserControl and... what else ? I tried to build it in a separate project, to see if I creating a separate dll will make a difference, though I really want it in the same project.
Please help ! (BTW I have reinstalled VS2010 and it did no good)
Thank you.
Look in Tools / Options / Windows Forms Designer and set "AutoToolboxPopulate" to True (but note that this can take a noticeable amount of time if you haver many (i.e. dozens) of user controls.
I would like to create a partial class for my form. I have a lot of events, and it gets messy, so I would like to break up sections into their own files.
The problem: When I create a partial class of my form, say:
Partial Public Class Form1
End Class
Visual Studio decides I need another form for this partial class.
Questions:
1. How do I create a partial class for a form?
2. If I cant do that, how can I break up all the events in my form into different files?
Yeah, it does. As soon as you drop a control on this phantom form, you'll get the design-time code (InitializeComponent) generated into that source code file. This is compatibility behavior for .NET 1.x, it didn't support the Partial keyword. Which will break the build, there are now two of them. It is somewhat avoidable with careful clicking, but you know it's going to happen sooner or later.
Other things go wrong too btw, the designer can no longer track an event handler when you move it from one file to another. And will readily let you add another, a much trickier source of bugs.
This just doesn't work very well, abandon hope of relying on it to solve your problem.
The generic diagnostic is that a convoluted user interface begets convoluted code. But that ship has sailed, no doubt. A more structural solution is pursuing the MVC model, separating the data from the view of the data. You'll still have a lot of event handlers but they won't do anything more than calling a method of a class that does the real work. Whose source code can of course live in another source code file. The typical hangup is that Windows Forms has no support whatsoever built in for this, you have to craft it by hand. Nothing similar to the MVVM model in WPF.
Something that can work well is isolating control + code into a separate UserControl. You have to do so carefully though, you don't want to have to add a bunch of properties and events that expose internal controls.
Sometimes I create partial classes for better readibility, especially when I have very large classes.
But when I click on the partial class, then the VS IDE will open the form editor showing me an empty form. If I do not care, than I could damage the main form (it seems to be a bug of VS 2008/2010)
A possibility could be using DesignerCategoryAttribute Class
Mark the partial class with the attribute "code".
<System.ComponentModel.DesignerCategory("code")>
Partial Class Form1
End Class
In this way when you click on the file, you open the class in the code editor.
Of course this will apply to all files, also to the main form file.
If you want to edit again your form in the form editor, you have to quote the attribute:
'<System.ComponentModel.DesignerCategory("code")>
Some more details here.
While it does not answer the original question, I found using regions made my code a little more manageable/readable.
#Region "RegionA"
#End Region
I orginally called this method a "hack", thus the comment below.
Not sure what you mean be "Visual Studio decides you need another form", however, are you sure the new Form1 partial class is declared in the corresponding original namespace?
All partial classes for a given .NET type must be declared in the same namespace of course (whatever files they're stored on).
I appreciate the answers given by Hans and I'm not disputing these at all. It is curious though that in Visual Studio 2010, when you create a form called say Main you get a Main.designer.vb which is a partial class. It says 'Partial Class Main' at the top. This class doesn't open a form when clicked. It also includes reference to Event Handlers. So I was wondering how do they get around this? Is there a way to create one of these 'special' partial classes that work as we would expect.
I noticed that when I created a Form Partial class, that the icon went from a class icon to a form icon. The icon associated with the Main.designer.vb file looks like a class icon with a arrow.
what worked for me (VS 2010) was naming Form1 class, already saved in Form1.vb with its own designer (Form1.Designer.vb) as:
Public Class Main 'saved in Form1.vb
VS updated the name in the designer as:
Partial Class Main 'saved in Form1.Designer.vb
then I created another "partial class" with the same name:
Partial Class Main 'saved in Main.vb
Whether I am editing Form1.vb or Main.vb VS shows me on the top navigation pan all the routines, functions, subs, even background workers and timers. For event handlers, to avoid the loophole mentioned earlier (you click on a control in the layout designer and a brand new event handler will be created in the original Form1.vb) I go:
Partial Public Class Main 'in Form1.vb file
Private Sub SomeControl_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles SomeControl.Click
Call SomeControlClick(sender, e)
End Sub
End Class
Partial Public Class Main 'then in Main.vb file
Private Sub SomeControlClick(ByVal sender As Object, ByVal e As System.EventArgs)
'blah blah
End Sub
End Class
In a Visual Basic project, I created a homemade TabControl in order to fix a visual bug. The control works properly, however whenever I modify the form using my tab, Visual Studio adds MyProject in front of the control in its declaration:
Me.tabMenu = New MyProject.MyClass 'Gives a BC30002 compile error
If I remove the MyProject., the project compiles properly.
MyClass is in a separate file MyClass.vb and looks mostly like this:
Public Class MyClass
Inherits System.Windows.Forms.TabControl
Public Sub New()
InitializeComponent()
MyBase.DrawMode = System.Windows.Forms.TabDrawMode.OwnerDrawFixed
End Sub
Protected Overrides Sub OnDrawItem(ByVal e As System.Windows.Forms.DrawItemEventArgs)
//OnDrawItem code
End Sub
Private Sub My_DrawItem(ByVal sender As Object, ByVal e As System.Windows.Forms.DrawItemEventArgs) Handles Me.DrawItem
//My_DrawItem code
End Sub
End Class
I tried removing the file and adding it again, copy and pasting the class inside MyForm.designer.vb, adding MyProject. to the class name, but nothing stopped Visual Studio from adding this so-hated MyProject.
Edit regarding this answer:
I understand the thing about the namespace, however my problem is mostly that the compiler does not recognize the class with the project name appended but still adds it everytime.
What is the actual compile error you are getting? Is it possable that the VB compiler is interpreting MyProject as something other than a namespace identifier? You could also try changing the default namespace for the project, then see what it does, it might give you a hint as to what the actual problem is.
You could also try changing the offending line to
Me.tabMenu = New Global.MyProject.MyClass
then let us know what the results are.
I've seen this before when you have a public module with the same name as your default namespace (project name). If that's the case, either rename the module or the default namespace and the problem should go away,.
By default, Visual Basic .NET assigned a default namespace to your project. (I believe the default is, in fact, MyProject.)
This is what's being prepended, and it's being done to explicitly identify your class in the designer.
No matter what your default namespace is for your project, the WinForms designer will add the namespace name to the .designer.vb file.
To change the default namespace, go to your project properties; it should appear on the first tab.
Also, generally, don't modify the .designer.vb files if you can avoid it. Those files get completely blown away and rebuilt by Visual Studio often, so your changes will more likely than not be eliminated.