How to retrieve text from dynamic label and display it to message box using dynamic button?

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I have these codes retrieving data from mysql database and display it into the dynamic panels, labels, and buttons. The problem is I don't know how to retrieve those texts from labels(lblProductName) to display it into message box when clicking the dynamic buttons(btnAddto). TIA!

VB.NET

Imports MySql.Data.MySqlClient
Module mdlMenu
Dim Cpanel As Panel
Dim lblProductName As Label
Dim btnAddto As Button
Dim count As Integer

Public Sub LoadMenu()
    Try
        SQLConnection()
        With sqlcom
            .CommandText = "SELECT * FROM tblproduct"
            .Connection = sqlconn
        End With
        Dim datareader As MySqlDataReader = sqlcom.ExecuteReader
        Do While datareader.Read()
            Cpanel = New Panel()
            With frmMenu

                count = .TableLayoutPanel1.Controls.OfType(Of Panel)().ToList().Count
                Cpanel.Location = New Point(10, (25 * count) * 7)
                Cpanel.Size = New Size(450, 160)
                Cpanel.Name = "Cpanel" & count
                Cpanel.AutoScroll = True
                Cpanel.BackColor = Color.White
                .TableLayoutPanel1.Controls.Add(Cpanel)

                lblProductName = New Label()
                lblProductName.Location = New Point(165, 10)
                lblProductName.AutoSize = True
                lblProductName.Name = "lblProd" & count
                lblProductName.Text = datareader.Item("ProductName").ToString & count
                lblProductName.Font = New Font(lblProductName.Font.FontFamily, 14, FontStyle.Bold)
                Cpanel.Controls.Add(lblProductName)

                btnAddto = New Button()
                btnAddto.Location = New Point(180, 115)
                btnAddto.Size = New Size(80, 40)
                btnAddto.Name = count
                btnAddto.Text = count
                btnAddto.Tag = count.ToString
                btnAddto.Font = New Font(btnAddto.Font.FontFamily, 10, FontStyle.Bold)
                AddHandler btnAddto.Click, AddressOf btnAddto_Click
                Cpanel.Controls.Add(btnAddto)
                count += 1
          End With
      Loop
    Catch ex As Exception
        MsgBox(ex.Message)
    Finally
        sqlconn.Close()
        sqlconn.Dispose()
    End Try
End Sub

What I have tried:

I tried the event handler event but it comes with error, I tried everything else but with no luck. Hope to help me with this. Thanks!

Posted 15-Aug-22 7:10am

Member 12839286

Updated 16-Aug-22 0:37am

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Comments

Member 15627495 15-Aug-22 17:17pm

as VB is about event purposes, you can go like this :

public sub btn_addtoclck(sender as object, e as eventarg)
if sender is typeof button then
dim temp_btn as button = sender // you allocate a copy of the clicked button
msgbox(temp_btn.Text)
end if

end sub

Member 15627495 15-Aug-22 17:26pm

another solution is to fetch again your dataset,
with the number of the panel ( count )
because of container and controls parent.

Member 15627495 16-Aug-22 0:11am

as a suggestion, to reduce your code a bit.

rewrite the scope in the loop.

there are redundant code when you initialise your objects

keep the dynamic line in the loop :
count = .TableLayoutPanel1.Controls.OfType(Of Panel)().ToList().Count
Cpanel.Location = New Point(10, (25 * count) * 7)

Cpanel.Name = "Cpanel" & count

.TableLayoutPanel1.Controls.Add(Cpanel)

lblProductName = New Label()

lblProductName.Name = "lblProd" & count
lblProductName.Text = datareader.Item("ProductName").ToString & count

Cpanel.Controls.Add(lblProductName)

btnAddto.Name = count
btnAddto.Text = count
btnAddto.Tag = count.ToString

AddHandler btnAddto.Click, AddressOf btnAddto_Click // very important to locate the event on the button dynamically
Cpanel.Controls.Add(btnAddto)
count += 1
end with

all the other lines can exists before the loop.

Member 15627495 16-Aug-22 0:23am

In the form structure,
all your controls are reachable by indexes.
it exists "parents containers" containing "childs controls"

your form is a "parent container", all the controls in the form are "childs controls".
a groupbox is a parent container too
a panel is a parent controls too.

with the following lines you can reach by indexes the "childs controls" in a "parent container" :

form1.controls.item(0) is the first control reachable in a form1
cpanel3.controls.item(2) is the third control in a cpanel3
groupbox2.controls.item(5) is the sixth control in the groupbox2

It's "root level" ( super parent ) contains sublevel 1 ( others controls or others parent controls ), which contains sublevel 2 ( others controls/parents controls in , and so and so ... )

Member 12839286 16-Aug-22 6:22am

I already followed your suggestions. Thanks for that, I now understand the concept. I gather all you ideas and I already have the solution.

CHill60 16-Aug-22 5:04am

"but it comes with error," - you should show that code, but more importantly tell us what the error was - exactly as it is presented to you.

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CHill60 · Accepted Answer · 2022-08-15T23:25:00

You are creating a panel per product containing a label and a button for that product and giving each control a name based on count

So you have a few options:
1) You will know when a, and which button was clicked (the sender argument). So you can look at it's Parent property Control.Parent Property (System.Windows.Forms) | Microsoft Docs[^]
The Panel is a container, so you can loop through it's controls (see the comments from Member 15627495) until you find the label (TypeOf Operator - Visual Basic | Microsoft Docs[^])

2) You could derive the actual name of the label from the name of the button that was clicked as they are all "grouped" by using count

3) Easier would be to store the name of the label you want in the Tag property of the button - Control.Tag Property (System.Windows.Forms) | Microsoft Docs[^] or derive it from the Tag you are already storing !

VB

btnAddto.Tag = count.ToString

VB

Dim associatedLabelName = "lblProd" & sender.Tag.ToString()

Then recursively search for that control name - example at Finding Controls on Forms -Deborah's Developer MindScape[^]

Caveat: I haven't got access to VB.NET at the moment, hence only links and no code samples

Member 12839286 · Accepted Answer · 2022-08-16T00:37:00

Private Sub btnAddto_Click(sender As Object, e As EventArgs)
    Dim button = DirectCast(sender, Button)
    Dim count = If(button.Tag IsNot Nothing, button.Tag.ToString(), String.Empty)
    Dim labels = frmMenu.Controls.Find("lblProd" & count, True)
    If (labels.Length > 0) Then
        Dim label = labels(0)
        MessageBox.Show(label. Text)
    End If
End Sub

I have these lacking codes on my program the If statement above. Finding control on my frmMenu, specifically a label named "lblProd". Controls.Find returns an array of Control.

How to retrieve text from dynamic label and display it to message box using dynamic button?

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