Partial Class _Default
Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
AddAndRemoveDynamicControls()
End Sub Private Sub AddAndRemoveDynamicControls()
'Determine which control fired the postback event.
Dim c As Control = GetPostBackControl(Page) If Not IsNothing(c) Then
'If the add button was clicked, increase the count to let the page know we want
'to display an additional user control
If c.ID.ToString = "btnAdd" Then
ltlCount.Text = Convert.ToInt16(ltlCount.Text) + 1
End If
End If 'Be sure everything in the placeholder control is cleared out
ph1.Controls.Clear() Dim ControlID As Integer = 0 'Since these are dynamic user controls, re-add them every time the page loads.
For i As Integer = 0 To (Convert.ToInt16(ltlCount.Text) - 1)
Dim DynamicUserControl As WebUserControl = LoadControl("WebUserControl.ascx")
'If this particular control id has been deleted from the page, DO NOT use it again. If we do, it will
'pick up the viewstate data from the old item that had this control id, instead of generating
'a completely new control. Instead, increment the control id so we're guaranteed to get a "new"
'control that doesn't have any lingering information in the viewstate.
While InDeletedList("uc" & ControlID) = True
ControlID += 1
End While 'Note that if the item has not been deleted from the page, we DO want it to use the same control id
'as it used before, so it will automatically maintain the viewstate information of the user control
'for us.
DynamicUserControl.ID = "uc" & ControlID 'Add an event handler to this control to raise an event when the delete button is clicked
'on the user control
AddHandler DynamicUserControl.RemoveUserControl, AddressOf Me.HandleRemoveUserControl 'Finally, add the user control to the panel
ph1.Controls.Add(DynamicUserControl) 'Increment the control id for the next round through the loop
ControlID += 1
Next
End Sub Private Function InDeletedList(ByVal ControlID As String) As Boolean
'Determine if the passed in user control id has been stored in the list of controls that
'were previously deleted off the page
Dim DeletedList() As String = ltlRemoved.Text.Split("|")
For i As Integer = 0 To DeletedList.GetLength(0) - 1
If ControlID.ToLower = DeletedList(i).ToLower Then
Return True
End If
Next
Return False
End Function Sub HandleRemoveUserControl(ByVal sender As Object, ByVal e As EventArgs)
'This handles delete event fired from the user control 'Get the user control that fired this event, and remove it
Dim DynamicUserControl As WebUserControl = sender.parent
ph1.Controls.Remove(sender.parent) 'Keep a pipe delimited list of which user controls were removed. This will increase the
'viewstate size if the user keeps removing dynamic controls, but under normal use
'this is such a small increase in size that it shouldn't be an issue.
ltlRemoved.Text &= DynamicUserControl.ID & "|" 'Also, now that we've removed a user control decrement the count of total user controls on the page
ltlCount.Text = Convert.ToInt16(ltlCount.Text) - 1
End Sub
Protected Sub btnAdd_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAdd.Click
'Handled in page load
End Sub
Protected Sub btnDisplayValues_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnDisplayValues.Click
ltlValues.Text = ""
For Each c As Control In ph1.Controls
'Find the specific user control that we added to this placeholder, and then get the selected values
'for the dropdownlist, checkbox, and textbox and print them to the screen.
If c.GetType.Name.ToLower = "webusercontrol_ascx" Then
Dim uc As UserControl = CType(c, UserControl)
Dim tbx1 As TextBox = uc.FindControl("tbx1")
Dim ddl1 As DropDownList = uc.FindControl("ddl1")
Dim cbx1 As CheckBoxList = uc.FindControl("cbx1") Dim sb As New System.Text.StringBuilder
sb.Append("Textbox value: " & tbx1.Text & "<br />")
sb.Append("Dropdown value: " & ddl1.SelectedValue & "<br />")
sb.AppendLine("Checkbox values: ") For Each li As ListItem In cbx1.Items
If li.Selected = True Then
sb.Append(li.Value & "<br />")
End If
Next sb.Append("<hr />") ltlValues.Text &= sb.ToString
End If
Next
End Sub
'Find the control that caused the postback.
'I got this code from http://www.ryanfarley.com/blog/archive/2005/03/11/1886.aspx
Public Function GetPostBackControl(ByVal page As Page) As Control
Dim control As Control = Nothing Dim ctrlname As String = page.Request.Params.[Get]("__EVENTTARGET")
If Not IsNothing(ctrlname) And ctrlname <> String.Empty Then
control = page.FindControl(ctrlname)
Else
For Each ctl As String In page.Request.Form
Dim c As Control = page.FindControl(ctl)
If TypeOf c Is System.Web.UI.WebControls.Button Then
control = c
Exit For
End If
Next
End If
Return control
End FunctionEnd Class
using Microsoft.VisualBasic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;partial class _Default : System.Web.UI.Page
{ protected void Page_Load(object sender, System.EventArgs e)
{
AddAndRemoveDynamicControls();
} private void AddAndRemoveDynamicControls()
{
//Determine which control fired the postback event.
Control c = GetPostBackControl(Page); if ((c != null)) {
//If the add button was clicked, increase the count to let the page know we want
//to display an additional user control
if (c.ID.ToString == "btnAdd") {
ltlCount.Text = Convert.ToInt16(ltlCount.Text) + 1;
}
} //Be sure everything in the placeholder control is cleared out
ph1.Controls.Clear(); int ControlID = 0; //Since these are dynamic user controls, re-add them every time the page loads.
for (int i = 0; i <= (Convert.ToInt16(ltlCount.Text) - 1); i++) {
WebUserControl DynamicUserControl = LoadControl("WebUserControl.ascx");
//If this particular control id has been deleted from the page, DO NOT use it again. If we do, it will
//pick up the viewstate data from the old item that had this control id, instead of generating
//a completely new control. Instead, increment the control id so we're guaranteed to get a "new"
//control that doesn't have any lingering information in the viewstate.
while (InDeletedList("uc" + ControlID) == true) {
ControlID += 1;
} //Note that if the item has not been deleted from the page, we DO want it to use the same control id
//as it used before, so it will automatically maintain the viewstate information of the user control
//for us.
DynamicUserControl.ID = "uc" + ControlID; //Add an event handler to this control to raise an event when the delete button is clicked
//on the user control
DynamicUserControl.RemoveUserControl += this.HandleRemoveUserControl; //Finally, add the user control to the panel
ph1.Controls.Add(DynamicUserControl); //Increment the control id for the next round through the loop
ControlID += 1;
}
} private bool InDeletedList(string ControlID)
{
//Determine if the passed in user control id has been stored in the list of controls that
//were previously deleted off the page
string[] DeletedList = ltlRemoved.Text.Split("|");
for (int i = 0; i <= DeletedList.GetLength(0) - 1; i++) {
if (ControlID.ToLower() == DeletedList[i].ToLower()) {
return true;
}
}
return false;
} public void HandleRemoveUserControl(object sender, EventArgs e)
{
//This handles delete event fired from the user control //Get the user control that fired this event, and remove it
WebUserControl DynamicUserControl = sender.parent;
ph1.Controls.Remove(sender.parent); //Keep a pipe delimited list of which user controls were removed. This will increase the
//viewstate size if the user keeps removing dynamic controls, but under normal use
//this is such a small increase in size that it shouldn't be an issue.
ltlRemoved.Text += DynamicUserControl.ID + "|"; //Also, now that we've removed a user control decrement the count of total user controls on the page
ltlCount.Text = Convert.ToInt16(ltlCount.Text) - 1;
}
protected void btnAdd_Click(object sender, System.EventArgs e)
{
//Handled in page load
}
protected void btnDisplayValues_Click(object sender, System.EventArgs e)
{
ltlValues.Text = "";
foreach (Control c in ph1.Controls) {
//Find the specific user control that we added to this placeholder, and then get the selected values
//for the dropdownlist, checkbox, and textbox and print them to the screen.
if (c.GetType.Name.ToLower == "webusercontrol_ascx") {
UserControl uc = (UserControl)c;
TextBox tbx1 = uc.FindControl("tbx1");
DropDownList ddl1 = uc.FindControl("ddl1");
CheckBoxList cbx1 = uc.FindControl("cbx1"); System.Text.StringBuilder sb = new System.Text.StringBuilder();
sb.Append("Textbox value: " + tbx1.Text + "<br />");
sb.Append("Dropdown value: " + ddl1.SelectedValue + "<br />");
sb.AppendLine("Checkbox values: "); foreach (ListItem li in cbx1.Items) {
if (li.Selected == true) {
sb.Append(li.Value + "<br />");
}
} sb.Append("<hr />"); ltlValues.Text += sb.ToString();
}
}
}
//Find the control that caused the postback.
//I got this code from http://www.ryanfarley.com/blog/archive/2005/03/11/1886.aspx
public Control GetPostBackControl(Page page)
{
Control control = null; string ctrlname = page.Request.Params.Get("__EVENTTARGET");
if ((ctrlname != null) & ctrlname != string.Empty) {
control = page.FindControl(ctrlname);
} else {
foreach (string ctl in page.Request.Form) {
Control c = page.FindControl(ctl);
if (c is System.Web.UI.WebControls.Button) {
control = c;
break; // TODO: might not be correct. Was : Exit For
}
}
}
return control;
}
public _Default()
{
Load += Page_Load;
}}
{
protected void Page_Load(object sender, EventArgs e)
{
AddAndRemoveDynamicControls();
}
private void AddAndRemoveDynamicControls()
{
//'Determine which control fired the postback event.
Control c = GetPostBackControl(Page); if (c != null)
{
//'If the add button was clicked, increase the count to let the page know we want
//'to display an additional user control
if (c.ID == "btnAdd")
ltlCount.Text = (Convert.ToInt16(ltlCount.Text) + 1).ToString();
} //'Be sure everything in the placeholder control is cleared out
ph1.Controls.Clear(); int ControlID = 0; //'Since these are dynamic user controls, re-add them every time the page loads.
for (int i = 0; i <= (Convert.ToInt16(ltlCount.Text) - 1); i++)
{
WebUserControl DynamicUserControl = LoadControl("WebUserControl.ascx");
//'If this particular control id has been deleted from the page, DO NOT use it again. If we do, it will
// 'pick up the viewstate data from the old item that had this control id, instead of generating
// 'a completely new control. Instead, increment the control id so we're guaranteed to get a "new"
//'control that doesn't have any lingering information in the viewstate.
while (InDeletedList("uc" + ControlID))
{
ControlID += 1;
} //'Note that if the item has not been deleted from the page, we DO want it to use the same control id
//'as it used before, so it will automatically maintain the viewstate information of the user control
//'for us.
DynamicUserControl.ID = "uc" + ControlID; //'Add an event handler to this control to raise an event when the delete button is clicked
//'on the user control
DynamicUserControl.RemoveUserControl += new EventHandler(this.HandleRemoveUserControl); // 'Finally, add the user control to the panel
ph1.Controls.Add(DynamicUserControl); //'Increment the control id for the next round through the loop
ControlID += 1;
}
}
private bool InDeletedList(string ControlID)
{
//'Determine if the passed in user control id has been stored in the list of controls that
//'were previously deleted off the page
string[] DeletedList = ltlRemoved.Text.Split("|");
for (int i = 0; i <= DeletedList.GetLength(0) - 1; i++)
{
if (ControlID.ToLower() == DeletedList[i].ToLower())
return true;
}
return false;
}
void HandleRemoveUserControl(object sender, EventArgs e)
{
//'This handles delete event fired from the user control //'Get the user control that fired this event, and remove it
WebUserControl DynamicUserControl = ((Control)sender).Parent;
ph1.Controls.Remove(DynamicUserControl); //'Keep a pipe delimited list of which user controls were removed. This will increase the
//'viewstate size if the user keeps removing dynamic controls, but under normal use
//'this is such a small increase in size that it shouldn't be an issue.
ltlRemoved.Text += DynamicUserControl.ID + "|"; //'Also, now that we've removed a user control decrement the count of total user controls on the page
ltlCount.Text = (Convert.ToInt16(ltlCount.Text) - 1).ToString();
}
protected void btnAdd_Click(object sender, EventArgs e)
{
// 'Handled in page load
}
protected void btnDisplayValues_Click(object sender, EventArgs e)
{
ltlValues.Text = "";
foreach (Control c in ph1.Controls)
{
// 'Find the specific user control that we added to this placeholder, and then get the selected values
//'for the dropdownlist, checkbox, and textbox and print them to the screen.
if (c.GetType().Name.ToLower() == "webusercontrol_ascx")
{
UserControl uc = (UserControl)c;
TextBox tbx1 = uc.FindControl("tbx1") as TextBox;
DropDownList ddl1 = uc.FindControl("ddl1") as DropDownList;
CheckBoxList cbx1 = uc.FindControl("cbx1") as CheckBoxList; System.Text.StringBuilder sb;
sb.Append("Textbox value: " + tbx1.Text + "<br />");
sb.Append("Dropdown value: " + ddl1.SelectedValue + "<br />");
sb.AppendLine("Checkbox values: "); foreach (ListItem li in cbx1.Items)
if (li.Selected)
sb.Append(li.Value + "<br />"); sb.Append("<hr />"); ltlValues.Text += sb.ToString;
}
}
}
// 'Find the control that caused the postback.
//'I got this code from http://www.ryanfarley.com/blog/archive/2005/03/11/1886.aspx
public Control GetPostBackControl(Page page)
{
Control control = null; string ctrlname = page.Request.Params["__EVENTTARGET"].ToString();
if (ctrlname != null && ctrlname != String.Empty)
control = page.FindControl(ctrlname);
else
foreach (string ctl in page.Request.Form)
{
Control c = page.FindControl(ctl);
if (c is System.Web.UI.WebControls.Button)
{
control = c;
break;
}
}
return control;
}
}