I have a group box with multiple Checkboxes(food item) and each one has a corresponding NumericUpDown control(quantity). For context, it is for a project based on a restaurant menu. I want to hide a button called btnSave whenever either a checkbox is unchecked or the quantity (NumericUpDown) is changed. I currently have btnSave.Hide under the CheckBox1_CheckedChanged and NumericUpDown1_CheckedChanged SubProcedures but I want to know if there's a way to do this when anything within this group box is changed instead of putting the code under each SubProcedure. Thanks
I think you meant .ValueChanged for the NumericUpDown control. (There is no .CheckedChanged) Although this doesn't matter much in this case, this is a good pattern for future reference. Instead of calling an event call a Sub from your events.
When you have several controls responding to a single Event handler, you can find out which control triggered the event by checking the sender parameter. Since, as you can see, sender is an Object you will have to cast it to the appropriate type to get the properties of a CheckBox.
Private Sub HideSaveButton()
btnSave.Hide
End Sub
Private Sub CheckBoxInGroupBox_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox1.CheckedChanged, CheckBox2.CheckedChanged
HideSaveButton()
Dim WhichCheckBox As CheckBox = DirectCast(sender, CheckBox)
Select Case WhichCheckBox.Name
Case "CheckBox1"
MessageBox.Show("CheckBox1 has changed")
Case "CheckBox2"
MessageBox.Show("CheckBox2 has changed")
End Select
End Sub
Private Sub NumericUpDown1_ValueChanged(sender As Object, e As EventArgs) Handles NumericUpDown1.ValueChanged
HideSaveButton()
End Sub
Related
I have an application where I have around 50 labels. In those labels a number is visible.
When the user clicks on the label the number needs to be written to an edit box.
This works fine, the only problem is that I have added 50 functions like below, and every time it’s the same. I was wondering if there is a common function for this
Remark: The labels have different names. So if its possible that this will work for all the labels on the form.
Private Sub LI_L_Click(sender As Object, e As EventArgs) Handles LI_L.Click
cmbOBJID.Text = LI_L.Text
End Sub
In the form designer, you should be able to set the handler for every label to the same function. Then you can use the "sender" parameter to determine which label is raising the event.
Notice also how all the controls that the function is linked to are listed after the "Handles" keyword. This is another way you could connect the code to all the labels if you prefer this over using the Visual Studio UI properties grid.
Private Sub LI_Click(sender As Object, e As EventArgs) Handles Label1.Click, Label2.Click, Label3.Click
cmdOBJID.Text = DirectCast(sender, Label).Text
End Sub
While it is easy to add several events to one handler in the style of
Private Sub LI_Click(sender As Object, e As EventArgs) Handles Label1.Click, Label2.Click, Label3.Click
It will be tedious for more than just a few labels.
You can add handlers programatically if you can find a way to refer to the labels you need to add handlers to. In this example, I put all the labels in a groupbox named "GroupBoxOptions":
Option Infer On
Option Strict On
Public Class Form1
Sub TransferDataToEditBox(sender As Object, e As EventArgs)
Dim lbl = DirectCast(sender, Label)
tbEditThis.Text = lbl.Text
End Sub
Sub InitLabelHandlers()
For Each lbl In GroupBoxOptions.Controls.OfType(Of Label)
AddHandler lbl.Click, AddressOf TransferDataToEditBox
Next
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
InitLabelHandlers()
End Sub
End Class
You may have some other way of selecting the labels which use the handler.
A pretty nice and quick solution is to traverse all the label controls on a form, assigning through the AddHandler function the event to run when a user clicks a label.
In code:
For Each c As Control In Me.Controls.OfType(Of Label)
AddHandler c.Click, AddressOf myLabelClick
Next
With the prevous snippet, we loop onto all the winform controls of type Label. A loop like that is useful when we have a lot of labels for which an event must be assigned. For each of them, we associate the event Click of the control with a customized Sub named myLabelClick. That subroutine will look like the following:
Private Sub myLabelClick(sender As Object, e As EventArgs)
cmdObjId.Text = DirectCast(sender, Label).Text
End Sub
Here we use the sender variable (which represents the control for which the click has been done) to access its Text property, and change the cmdObjId.Text accordingly.
Just to complement the solution from BlueMonkMN:
If you are using the DevExpress Tools, you need to import DevExpress.XtraEditors and change Label to LabelControl:
DirectCast(sender, LabelControl).Text
This worked for me.
I want to add the same event on my multiple textboxes. Let's say for example I want all my textboxes to trim the text value of itself when it has lost focus
my idea is to loop through all the textboxes and to add an event handler to all of it, but how will I refer to the textbox itself, I think it is the same as using the "this" keyword, but it is not available in vb.net - any other recommendations?
In order to get the element which triggered the event you can use the sender parameter of the event and cast it to the required type. It is not clear from the question which platform you are using, but below is the sample code for Windows Forms:
Private Sub txt1_TextChanged(sender As Object, e As EventArgs) Handles txt1.TextChanged
Dim currentTextbox as TextBox = CType(sender, TextBox)
' Do what you want with the textbox
End Sub
Similar principles should apply to Web forms or WPF as well.
Through all the textboxes Use handles for all textboxes
Private Sub TextBox1_LostFocus(sender As Object, e As EventArgs) _
Handles TextBox1.LostFocus, TextBox2.LostFocus
Dim txtBox As TextBox = sender
txtBox.Text = Strings.Trim(txtBox.Text)
End Sub
My combobox that has 2 item. This box has a selecteindexchange event. How do I get this event to fire off again if the user chooses the same item the second time around?
This seems to work in your case
Private Sub ComboBox1_SelectionChangeCommitted(sender As Object, e As EventArgs) Handles ComboBox1.SelectionChangeCommitted
End Sub
At this point the ComboBox doesn't have a selected text so use ComboBox1.SelectedItem which is populated at this point.
I have a NumericUpDown Control on a form. In the Application Settings / Properties Binding, for the value parameter, i can't select my USER setting called : Heures (Integer / User).
I tried to save the value by this way :
Private Sub NumericUpDownHeures_Leave(sender As System.Object, e As System.EventArgs) Handles NumericUpDownHeures.Leave
My.Settings.Heures = NumericUpDownHeures.Value
My.Settings.Save()
End Sub
But it's not saved.
No problem for other settings (String / User). But i don't understand why the settings (Integer / User) are not saved.
Please help, Thanks.
As you are putting "NumericUpDown1.Value" you have to set the value at My.Settings.Heures to decimal.
In Form1_Load add:
NumericUpDownHeures.Value = My.Settings.Heures
and add to the event listener for your button or other widget:
My.Settings.Heures = NumericUpDownHeures.Value
I would guess the issue is that the Leave event is not being fired as you expect it to be, especially if the user just clicks the up/down arrows. I suspect that it is only fired when the user actually clicks into the value area, then leaves. You could verify this by debugging to see if your code is ever hit or by showing a simple msgbox from that event.
I think that you will have better luck if you hook the LostFocus or ValueChanged event.
I want to add to this as well for anyone looking at this in the future.
Save your settings as shown already by putting
My.Settings.Heures = NumericUpDownHeures.Value into your ValueChanged event, and then doing reverse in the form load event.
The problem is, this value changed event fires before the form load when you first initialize, so it will keep defaulting to whatever value you have set in the designer because you're overwriting the setting value with the designer value.
To get around this, you need a private/public boolean at the top of your code that is only set to true once your form has loaded (set to true at the bottom of your form_load event), then you can add the condition to the ValueChanged event checking if the form is loaded yet or not. If it is, then change the setting value, if not, then don't.
An example:
Private IsFormLoaded As Boolean = False
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
NumericUpDown1.Value = My.Settings.SavedNumValue
IsFormLoaded = True
End Sub
Private Sub NumericUpDown1_ValueChanged(sender As Object, e As EventArgs) Handles NumericUpDown1.ValueChanged
If IsFormLoaded = False Then Exit Sub
My.Settings.SavedNumValue = NumericUpDown1.Value
End Sub
OR
Private Sub NumericUpDown1_ValueChanged(sender As Object, e As EventArgs) Handles NumericUpDown1.ValueChanged
If IsFormLoaded Then
My.Settings.SavedNumValue = NumericUpDown1.Value
End If
End Sub
i have a couple of questions about my basic project
if i have a check box and when its checked, it is going to a text box which is displaying the price, when i uncheck it my price still says in that text box, how can i make it dissapear as i uncheck the box?
Dim total As Double
If rb_s1.Checked = True Then
total += 650.0
txt_1.Text = total
thats my code.
and i have many combo boxes, how can i make them all add up as i check/uncheck them.
I would add this functionality into the CheckBox_Changed event handler. This way you can tell if it is unchecked or checked and add or subtract the value from price.
Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
If CheckBox1.Checked Then
total += 650.00
Else
total -= 650.00
End If
TextBox1.Text = total.ToString()
End Sub
You have to use Checked_Changed event of checkbox.
SHARED void CheckBox1_CheckedChanged(object sender, EventArgs e)
IF ChkBx.Checked = true then
textBox1.text = "1500"
else
textBox1.text = ""
END IF
END SUB
To get your displayed text to change when the state of your checkbox changes, you'll need to handle the CheckedChanged event. In Visual Studio while in Desginer mode for your form/control, you can select the check box control, and then in the Properties window, select the Events tab (the one with the little lightingbolt icon), and double click the CheckChanged event to stub in an event handler method AND attach the event to the handler.
ETA: I re-reading this, I'm not sure how clear I was. When I mentioned stubbing in the event handler and attaching the event to the handler, I meant that going the route of double-clicking the event in the designer will do this for you.
As an aside, it sounds like you want the text to be a sum of only the checked items, so from an architechtueral sense, I would recommend creating a single method to determine the sum, and have all check-box check events invoke that method rather than trying to make the event handler method itself do too much directly (maybe that was already clear to you).
So you might do something like this:
Public Class Form1
Private Sub DisplayTotal()
Dim total As Decimal = 0
If (CheckBox1.Checked) Then
total += Decimal.Parse(txtItem1.Text)
End If
'Add other items
txtTotal.Text = total
End If
End Sub
Private Sub CheckBox1_CheckedChanged(sender As System.Object, e As System.EventArgs) Handles CheckBox1.CheckedChanged
DisplayTotal()
End Sub
Private Sub CheckBox2_CheckedChanged(sender As System.Object, e As System.EventArgs) Handles CheckBox1.CheckedChanged
DisplayTotal()
End Sub
End Class