I'm trying to add a load event to a form so that the data on the form (pulled from a DB), will refresh after the user performs an add, delete, or update. Each of these functions is accessed by a click event. The form_Load event is the last line of code in the subroutine calling the click event.
I've made sure the name of the form matches the name in the Load event call, and I've made sure that the form isn't still named "Form1" elsewhere the code.
Here is the code used for each of my Load event calls:
Option Strict On
Public Class frmHome
Private Sub mySub
' do something
'Refresh frmHome to show new customer
frmHome_Load(sender, e)
End Sub
Here is the error message:
Error BC30451 'frmHome_Load' is not declared. It may be inaccessible due to its protection level.
Here's an example of what Jimi is talking about:
Public Class frmHome
Private Sub frmHome_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Foo()
End Sub
Private Sub Foo()
' ... code ...
End Sub
Private Sub mySub()
' do something
Foo()
End Sub
End Class
Related
I have a vb.net application which contains two forms. One is called "MapComponentForm" and another called "ComponentPropertiesForm". In the MapComponentForm I have defined an event which I want fired when the OK button is clicked. If the ComponentPropertiesForm is open, I want it to "hear" this event and act accordingly. Stepping through the code the event seems to fire as expected but the ComponentPropertiesForm seems to be oblivious to this. I've attached the code from the two forms after stripping out the non relevant code in hopes that someone can tell me why my event goes unheeded. I used the information here:
https://learn.microsoft.com/en-us/dotnet/visual-basic/programming-guide/language-features/events/walkthrough-handling-events
in constructing my own code.
Thanks for any suggestions.
Public Class MapComponentForm
Public Event PartMapped(ByRef status As Boolean)
Public Sub New(shape As Visio.Shape)
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
_shape = shape
End Sub
Private Sub OkButton_Click(sender As Object, e As EventArgs) Handles OkButton.Click
'If the component properties window is open, refresh it
If Application.OpenForms().OfType(Of ComponentPropertiesForm).Any Then
RaiseEvent PartMapped(True)
End If
end sub
end class
Public Class ComponentPropertiesForm
Private WithEvents mPartMap As MapComponentForm
Private Sub ComponentPropertiesForm_Load(sender As Object, e As EventArgs) Handles Me.Load
mPartMap = New MapComponentForm(Nothing)
End Sub
Private Sub mPartMap_PartMapped(ByRef status As Boolean) Handles mPartMap.PartMapped
If status = True Then
MsgBox("something got mapped")
End If
End Sub
end class
I have two separated form(usercontrol A & B) in VB.Net. When a button clicked on formB, I want to an event raised on formA. How can do that? I searched stackoverflow.com and check several related solutions but they didn't work for me. I don't know what is the problem! Please help me.
For Example I tried this code:
FormA:
Dim MyEditForm As New ucEmployeeTimeEdit
'some code for showing and preparing MyEditForm
Private Sub GetSomeClick() Handles MyEditForm.MyClick
System.Console.WriteLine("test")
End Sub
FormB:
Public Event MyClick()
Private Sub BtnDelet_Click(sender As Object, e As EventArgs) Handles btnDelet.Click
RaiseEvent MyClick()
End Sub
While Idle_Mind answer is great, here's an alternative method with different advantages. (EDIT: I just noticed that he mentions this too, so you can consider this an elaboration on this subject)
If you keep FormB as a modal variable inside FormA, you can tell VB that you want to use it's events. Here's some skeleton code to show you:
Public Class FormA
Private WithEvents myFormB As FormB
'rest of the code for FormA
'you can use FormB's events like this
Private Sub GetSomeClicks() Handles myFormB.MyClick
'code code code
End Sub
End Class
Public Class FormB
Public Event MyClick()
End Class
Have fun!
Somewhere in the some code portion, you need to use AddHandler to "wire up" that event:
Public Sub Foo()
Dim MyEditForm As New ucEmployeeTimeEdit
'some code for showing and preparing MyEditForm
AddHandler MyEditForm.MyClick, AddressOf GetSomeClick
End Sub
Private Sub GetSomeClick()
System.Console.WriteLine("test")
End Sub
Note that GetSomeClick() does not have a "Handles" clause on the end. This is because your instance of ucEmployeeTimeEdit was a local variable.
If you had declared it as WithEvents at class level, then you could use the "Handles" clause (and consequently would no longer need the AddHandler call).
i need help with my code
Public Class Forma
Private Sub ProjectToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ProjectToolStripMenuItem.Click
If ProjectToolStripMenuItem_Click() Then
Print(Form_load)
End If
End Sub
Private Sub Form_load(FormB As Object)
End Sub
End Class
but i keep getting BC30455 Argument not specified for parameter 'sender' of. What am i doing wrong
Your condition want to check the result of the event ProjectToolStripMenuItem_Click (click event of ProjectToolStripMenuItem). On this function you don't define the sender and e parameter.
You should review your code and fix the issues:
Public Class Forma
Private Sub ProjectToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ProjectToolStripMenuItem.Click
If exampleFunction() Then '<-- choose the correct function or variable
Print(Form_load) '<-- Form_load?? maybe FormB??
End If
End Sub
Private Sub Form_load(FormB As Object)
End Sub
End Class
Some basics you should know:
A Sub doesn't return a value, so you can't use a Sub on a condition (only functions, variables and values can be used on a condition).
It looks like you check if the button / menu item was clicked by the user. You don't need to check because the event ProjectToolStripMenuItem_Click is called automatically if the user click on ProjectToolStripMenuItem. At the point you try to check the button / menu item was clicked it was actually clicked. You can find more information about Event Handlers on the official .NET docs.
The error message should be clear enough to solve the issue:
You have not supplied an argument for a required parameter.
To correct this error:
Supply an argument for the specified parameter.
source: https://learn.microsoft.com/en-us/dotnet/visual-basic/misc/bc30455
You try to print the form on button click?
Public Class Forma
Private printForm as Object
Private Sub ProjectToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ProjectToolStripMenuItem.Click
If ConditionIsTrue() Then '<-- choose the correct Sub or Function
Me.printForm.Print()
End If
End Sub
Private Sub Form_load(FormB As Object)
'... maybe some other stuff
Me.printForm = FormB
'... maybe some other stuff
End Sub
End Class
You cannot pass a Sub as a Parameter Print(Form_load). FormB.Print() might be what you are looking for.
This looks like a problem : If ProjectToolStripMenuItem_Click() Then
It's a call to the same sub and it has no parameters specified.
I am kinda new to visual basic and was wondering if it is possible to trigger events in a class, based on action with in form.
So the following is my problem:
I have a form called Main, with a picture box called picPID
And a class called add_new
What I want to do is:
when the right mousebutton is clicked, the code for the event handling is placed within the class called add_new
I thought i could just declare it in the following way:
Sub meMouseDown(sender As Object, e As MouseEventArgs) Handles Main.picPID.MouseDown
But I get an error saying i have to declare it withEvents, I tried to declare the picturebox as:
Public shared withEvents as picturebox
but it dident help, any sugestions? It is not a problem having the code within the Main form, but it would result in a lot of code, so I was hoping to split it up.
So you have the class with an eventhandler:
Public Class add_new
Public Sub PictureBoxEventHandler(sender As Object, e As MouseEventArgs)
'Your Implementation
End Sub
End Class
Then you need an instance of this class within the form containing the picturebox:
Public Class Form1
Private add_New_Command As New add_new ' hold a reference to the command
'constructor
Public Sub New()
InitializeComponent()
' and add the handler to the event of the picture box ... hook it up
AddHandler PictureBox1.MouseDown, AddressOf add_New_Command.PictureBoxEventHandler
End Sub
End Class
I've been trying to understand this for a few days now and wonder if it's something simple I'm missing or doing completely wrong.
Example:
Two files - TestClass.vb, myForm.vb
TestClass.vb looks as follows:
Imports System.Threading
Public Class TestClass
Private myClassThread As New Thread(AddressOf StartMyClassThread)
Public Sub Start()
myClassThread.Start()
End Sub
Private Sub StartMyClassThread()
myForm.Msg("Testing Message")
End Sub
End Class
myForm.vb is a basic form with a listbox control and a button control named respectively Output and StartButton.
The code behind the form is as follows:
Public Class myForm
Private classEntity As New TestClass
Private Sub StartButton_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles StartButton.Click
Msg("Start Button Pressed")
classEntity.Start()
End Sub
Delegate Sub MsgCallBack(ByVal mesg As String)
Public Sub Msg(ByVal mesg As String)
If Output.InvokeRequired Then
MsgBox("Invoked")
Dim d As New MsgCallBack(AddressOf Msg)
Invoke(d, New Object() {mesg})
Else
MsgBox("Not Invoked")
mesg.Trim()
Output.Items.Add(mesg)
End If
End Sub
End Class
The result:
Application runs, no errors or exceptions.
Displayed is the listbox and the Start button.
I press the start button and a msgbox says "Not Invoked" as expected and upon clicking OK to that msgbox "Start Button Pressed" is added to the Output listbox control.
Immediately following that the msgbox pops up again and says "Not Invoked". I was expecting "Invoked" as a separate thread is trying to use the Output listbox control.
Of course this results in the Output.Items.Add being attempted which results in no visible result as the thread is not allowed to directly update the UI control.
I must've read a small books worth of different pages trying to thoroughly understand pit falls and methods but I feel I may have fallen into a trap alot of people may do.
With my current understanding and knowledge I'm unable to get out of that trap and would appreciate any input or advice.
Kind regards,
Lex
The problem here is that you are calling the function Msg not on an instance of myForm, but as a shared function of the class myForm.
Change your code in TestClass to add
Public FormInstance as myForm
and then replace
myForm.Msg("Testing Message")
with
FormInstance.Msg("Testing Message")
Then in StartButton_Click add the line
classEntity.FormInstance = Me
and you will get the expected result.