Placeholder
The placeholder control saves a spot for you to programmatically add or remove controls.
You can add or remove as many controls as you want to the placeholder control
Use the Add method to add controls to the placeholder
Use the remove method to remove them
- Open Visual Studio
- Add a new webform
- Name it Placeholder.aspx
- Click the Add button
- Select the Design View
- Add 3 RadioButton controls
- Name then
- Opttextbox
- Optlabel
- Optbutton
- Set the text properties to
- Set the groupName of them all to controlType
- Set the autoPostback properties to true for all 3
- Add a button control
- Set the name to btnSubmit
- Set the text to Submit
- Add a Placeholder control
- Double-click the button and add this code:
If optTextbox.Checked Then
myPlaceholder.Controls.Add(textbox1)
textbox1.Text = ""
End If
If optLabel.Checked Then
myPlaceholder.Controls.Add(label1)
label1.Text = "Hello World"
End If
If optButton.Checked Then
myPlaceholder.Controls.Add(button1)
button1.Text = "Submit"
End If
- Above the subroutine add this code:
Dim button1 As Button = New Button()
Dim textbox1 As TextBox = New TextBox()
Dim label1 As Label = New Label()
1 |
Dim button1 As Button = New Button() |
2 |
Dim textbox1 As TextBox = New TextBox() |
3 |
Dim label1 As Label = New Label() |
1 |
Dynamically creates a button control in memory |
2 |
Dynamically creates a textbox control in memory |
3 |
Dynamically creates a label control in memory |
1 |
If optTextbox.Checked Then |
2 |
myPlaceholder.Controls.Add(textbox1) |
3 |
textbox1.Text = "" |
4 |
End If |
5 |
If optLabel.Checked Then |
6 |
myPlaceholder.Controls.Add(label1) |
7 |
label1.Text = "Hello World" |
8 |
End If |
9 |
If optButton.Checked Then |
10 |
myPlaceholder.Controls.Add(button1) |
11 |
button1.Text = "Submit" |
12 |
End If |
1 |
Check to see if the first radioButton is checked |
2 |
If it is checked add the textbox control that was created dynamically to the controls collection of the placeholder |
3 |
Erase the default text on the textbox |
4 |
End the if statement |
5 |
Check to see if the second radioButton is checked |
6 |
If it is checked add the label control that was created dynamically to the controls collection of the placeholder |
7 |
Change the default text on the label to Hello World |
8 |
End the if statement |
9 |
Check to see if the third radioButton is checked |
10 |
If it is checked add the button control that was created dynamically to the controls collection of the placeholder |
11 |
Change the default text on the button to Submit |
12 |
End the if statement |