I wonder how do I reference the user form in which the sender control is located? I have a programmatically created button control and user form in which it's located and when clicking on it I need to reference the user form to grab a value from a combobox in that form to use it as a variable and I can do it descending i.e. get the sub control of the sender but how do you get the control above the sender?
Sub DynamicForm_NewForm_SmartHUB_ProjectsActivated(ByVal sender As Object, ByVal e As EventArgs)
strProjectTypeFolderName = '(form in which the sender is located).combobox_ProjectType.selecteditem
End Sub
You'd first need to cast the sender as Control at least. You can then access the Parent property, although that property is type Control and may not be a form, if the sender is in a Panel, GroupBox or some other container. You ought to call the FindForm method instead. It will return a Form reference and it will also get the containing form no matter how deeply the sender is nested.
If you have Option Strict On, which you probably don't but you definitely should, even a Form reference won't be sufficient. The Form class has no combobox_ProjectType field, so you'd need to cast it as it's actual type - Form1 or whatever - in order to access that field without using late binding.
Related
I'm having this issue that should be pretty easy to solve but I just can't seem to figure it out or find an answer yet. I have the following code:
Public Sub NotifyThatValuesChanged(sender As Object, e As EventArgs)
APIUserForm_MAIN.OnSecurityInputValuesChanged()
APIUserForm_MAIN.MessageSender.TabControl.SelectTab(0)
End Sub
So, I'm rasing events when values within txtboxes change, and one of the things I want to do is change tab focus when these values change, which it is doing...but....I don't want the cursor (or focus) to change to the selected tab. I want the cursor/focus to stay where it is at while this event happens, and for the tab selected on this other control to change from (1) to (0).
Thanks for the help!!!!
I don't think it's 100% possible. Try putting the focus back into the textbox:
Public Sub NotifyThatValuesChanged(sender As Object, e As EventArgs)
APIUserForm_MAIN.OnSecurityInputValuesChanged()
APIUserForm_MAIN.MessageSender.TabControl.SelectTab(0)
TextBox1.Select()
End Sub
If multiple controls are calling this method, you can use the sender parameter:
DirectCast(sender, Control).Select()
I'm not sure if the question properly asks what I want, because I'm a bit new, but what I am trying to do is write a sub or function that I can run when a label is clicked, and I want to to be reusable on multiple labels. There will be 12 in total, and I don't wish to write the same thing over and over, with slightly different characters. A programmer never wants to write the same thing twice, right? Also, something else is making it a necessity to do it dynamically.
So, how I was trying to accomplish that was by using a string, and adding the name of the label to the string on click.
click1 = "Label1"
As it turns out, you can't just say click1.Text and return the text of Label1. The reason it's important to do it implicitly is because I need to somehow remember the one I clicked before, to compare the first click and second click, and if they match, do A, and if they don't match, do B.
The first parameter (it is called sender) to the event handler your wrote to respond to the click event is the object which sent the event.
If you assign the same routine to respond to on click of all your labels, it will be called for every one of them, but the sender parameter will point to the actual label which was clicked
HTH
mfeingold is correct, if you're unsure of the syntax:
Private Sub LabelClicked (ByVal sender As Object, ByVal e As EventArgs) Handles Label1.Click, Label2.Click, Label3.Click
sender.Text = "I've been clicked."
End Sub
How can I refer to the control while I am inside a control's method in VB.NET?
For example, I want in a textbox to show a message box with that textbox's text every time the text changes. The code would be something like:
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
msgbox("The text is:"+ Me.text)
' ok the line above wont work i already know that, because "Me" refer to the form,
' not the control textbox1
' how i will refer to the textbox1's text???
' i dont want to use "textbox1.text" is there a way similar like the "Me" is for forms?
' because i want to copy-paste a code like this in a lot of controls and do not want to
' have to change in every copy the name to each control name
End Sub
I hope I made myself clear; my English needs some improvement :D
No, there's no keyword that allows you to do that. However, every event raised by a control passes in a sender parameter that you can use to determine which particular control raised that event.
Note that this parameter is always typed as a basic Object (because it can represent any possible control), so you'll need to downcast to a more specific control class if you need to access any of the unique members that it exposes. Since you're handling an event raised by a TextBox control, you know that the sender must be of type TextBox, so you can simply use DirectCast to handle the upcasting. You don't have to worry that an InvalidCastException will be thrown.
For instance, your above example would become:
Private Sub TextBox1_TextChanged(ByVal sender As Object, ByVal e As EventArgs) Handles TextBox1.TextChanged
Dim textBox As TextBox = DirectCast(sender, TextBox)
MessageBox.Show("The text is: " & textBox.Text)
End Sub
That being said, there are a couple of concerning things that jump out at me in your question:
Any time that your approach to solving a problem is "copy-pasting" code, you should stop, take a step back, and try to figure out if there's any better way to achieve your ultimate goal.
For example, if you need every textbox on your form to react in the same way whenever a particular event is raised, you should consider subclassing the existing TextBox control and consolidating all of your code in one place. Remember that you can inherit off of most of the standard controls to add custom functionality. This is often a far better solution than copying and pasting code to multiple places in your project. If you ever need to track down a bug or modify that functionality, you'll only have to change it one place in your code, rather than several. As a somewhat cheekier benefit, you'll be able to use Me to refer to that control when you're editing its subclass.
You should always prefer to concatenate (combine) strings using the & operator in VB.NET, rather than the + sign. Or perhaps even better, the String.Concat or String.Format methods.
There is no reason to use MsgBox in VB.NET, as opposed to MessageBox.Show. No, this won't improve performance of your application, but it's a good practice to get into for .NET languages.
The sender variable contains the TextBox instance you want to access. You only need to convert the sender to TextBox.
When we click on drop down combobox control in our windows form, it shows the list automatically.
But when we press tab and navigate to that control from keyboard it doesn't shows the list automatically. So in other to show the list automatically on receiving focus what should be done?
Set the DroppedDown property of the combobox equal to true.
Private Sub myComboBox_GotFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles myComboBox.GotFocus
myComboBox.DroppedDown= true
End Sub
I would like to mention on thing here.
I used Enter event to show Drop down list with DroppedDown=true,
But When I type something in text area of combobox and if i leave the area to next control, entered text is lost.
My combobox is databound.
I am new to Win Forms, I have a scenario here..
When User enter ID in a textbox, I want to check that value in database and get the name for that ID before submitting the Submit Button.
In webforms it can be done using OnFoucs and OnBlur events but how can I do here before submitting the button.
I am using .NET 1.1
Regards
SBMARYA
I am able to do it using Leave Event of the TextBox control.
Private Sub txtID_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtID.Leave
End Sub
Thanks
sbmarya