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.
Related
I'm a newbie on vb.net, and I was in progress with my first application... and found some example code in the msdn so I just replaced my Form1.vb file content with the content from the MSDN. When I roll back the changes, and tried to compile my old code then hundreds of errors appeared, and when I switch to the Form1[Design] tab I see this:
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.
I'm really new on vb.net and the visual studio itself, and I dont know what to do in this case, is my work destroyed or what?
That's because you added some class or other code above the class definition in form1.vb. Remove that.
What worked for me is editing both Form1.vb and Form1.Designer.vb and placing at the beginning of both files: Namespace Whatever and at the end of both files: End Namespace. The "Whatever" can be any name not already used in the program (or the name of an existing Namespace that you're already using).
You added another class in your form and that is the reason of the error. I had ran into same issue. I had added another class in the form and that caused this error. To resolve, I moved the new class to a module(created new module) and then access the class in the required form.
I was commenting out code in my project and starting getting errors in the designer which stopped me from viewing the page.
After this i decided to put everything back so I was able to run the program again. (Yes, i have made sure to comment everything back)
I am now getting designer errors on some of my pages. Here is the errors and examples.
Here is the list of errors I am getting:
http://i.stack.imgur.com/NFX8G.png
The application does run but if i click on the frmMediaDevices1.vb page this is the errors that then appears:
http://i.stack.imgur.com/XZrPE.png
I think it maybe something to do with the Windows.Media.Player that i have referenced in the project on frmMain.vb as when I click the errors the designer code appears highlighting my media player on the page.
Does anyone know how I can maybe refresh the designer? Or know how i can fix this issue?
Form's class must be the first in the form's class module.
Problem you described happens if you have files like
Form1.designer.vb
Form1.vb
Form1.resx
and into file Form1.vb which contains Class Form1 you add class Class Helper1. You can do it, but class Form1 must be kept as the first class (tompost in code) in Form1.vb.
Of course, this also includes the case if you have only one (proper) class in the file (Class Form1), but you comment it out.
Just be careful with your commenting and you will avoid that error.
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 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.
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