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C# Event Handlers For Dynamically Created DropDownLists

Hello..I have a similar issue as yesterday but the situation has
slightly changed so perhaps someone can shed some more light on the

Program flow - load file,extract xml text tags from file,then depending
on the number of Xml tags retrieved from the file determines the number
of dropdownlist controls instanciated in the placeholder,the user
selects the required tags from the
dropdownlists (if 5 Xml tags,then 5 dropdownlists each containing 5 xml
tags) and now the btnSave button is selected which extracts the user
selection form the dropdownlists.

Once btnLoadXmlTags_Click function is called,an array is filled with the
xml tags,this function also creates a session variable call
"OkToRecreateControls" which permits Page OnInit to recreate the dynamic
controls for subsequent postbacks,then the
btnLoadXmlTags_Click function calls the CreateDynamicControls which in
turn calls the function AddContentToDynamicControls.

The above works fine and for subsequent postbacks page onInit can call
CreateDynamicControls which will now run since the
"OkToRecreateControls" session variable is now valid.

Problem - when the user selection is extracted form the dropdownlists
using the btnSave function the first dropdownlist works fine,but the
other dorpdownlists
return the values as selected in the first dropdownlist rather then
their own content ...Theo

Code Sample

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.IO;
using System.Xml;
using System.Data.SqlClient;
using System.Configuration;

namespace AspXmlDbMapper_v2

public class wfrmMain4_BackUp : System.Web.UI.Page

protected System.Web.UI.Page Me;
protected System.Web.UI.WebControls.PlaceHolder plhDbContent;
protected System.Web.UI.WebControls.PlaceHolder plhXmlContent;
protected System.Web.UI.HtmlControls.HtmlInputFile fileDb;
protected System.Web.UI.HtmlControls.HtmlInputFile fileXml;

protected System.Web.UI.WebControls.Button btnLoadDb;
protected System.Web.UI.WebControls.Button btnLoadDbAttributes;
protected System.Web.UI.WebControls.Button btnLoadXml;
protected System.Web.UI.WebControls.Button btnLoadXmlTags;
protected System.Web.UI.WebControls.Button btnSave;
protected System.Web.UI.HtmlControls.HtmlGenericControl span1;
protected System.Web.UI.HtmlControls.HtmlGenericControl span2;
protected System.Web.UI.WebControls.DropDownList ddlXmlTagList;
protected System.Web.UI.LiteralControl literal;

protected System.Web.UI.LiteralControl[] aryLieralCtrls;
protected System.Web.UI.WebControls.DropDownList[] aryDdlCtrls;

private string xmlFileDestination = "";
private ArrayList aryTxtNodes = new ArrayList();
private ArrayList aryEleNodes = new ArrayList();
protected System.Web.UI.WebControls.DropDownList ddlXmlTagList1;
private ArrayList aryAtrbNodes = new ArrayList();

private void Page_Load(object sender, System.EventArgs e)


#region Web Form Designer generated code
override protected void OnInit(EventArgs e)

private void InitializeComponent()
this.btnLoadXml.Click += new System.EventHandler(this.btnLoadXml_Click);
this.btnLoadXmlTags.Click += new
this.btnSave.Click += new System.EventHandler(this.btnSave_Click);
this.Load += new System.EventHandler(this.Page_Load);


private void btnLoadDb_Click(object sender, System.EventArgs e)
if (fileDb.PostedFile != null )
string dbFilePath = "C:\\TempXml";
string fileName = Path.GetFileName(fileDb.Value);
string dbFileDestination = Path.Combine(dbFilePath,fileName);

span1.InnerHtml = "File uploaded successfully to <b>" +
dbFileDestination + "</b>";

catch (Exception exc)
span1.InnerHtml = "Error saving file <b>" + dbFileDestination +
"</b><br>"+ exc.ToString();


private void btnLoadXml_Click(object sender, System.EventArgs e)
string fileDestination = "C:\\TempXml";
string fileName = Path.GetFileName(fileXml.Value);
string fileExtentsion = Path.GetExtension(fileXml.Value);

xmlFileDestination = Path.Combine(fileDestination,fileName);
Session["xmlFilePath"] = xmlFileDestination;

if (fileXml.PostedFile != null )
//error check...file has .xml extentsion
if (fileExtentsion.ToString().Equals(".xml"))
span2.InnerHtml = "File uploaded successfully to <b>" +
xmlFileDestination + "</b>";
Session["xmlFileLoadedOk"] = true;
catch (Exception exc)
span2.InnerHtml = "Error saving file <b>" + xmlFileDestination +
"</b><br>"+ exc.ToString();
MsgBox("Error...loaded incorrect file type \\n\\nCorrect file type is
\" filename.xml \"");

private void btnLoadXmlTags_Click(object sender, System.EventArgs e)
int elementCount=0, attributeCount=0, textCount=0;

string fileDestination = (string)Session["xmlFilePath"];
StreamReader streamreader = new StreamReader (fileDestination);
XmlTextReader xmlReader = new XmlTextReader (streamreader);

while (xmlReader.Read())
string myNode = "";

switch (xmlReader.NodeType)
case XmlNodeType.Element:
myNode = xmlReader.Name;
if (xmlReader.HasAttributes)
myNode = xmlReader.Value;
case XmlNodeType.Text:
//assign last element name tag and current text value to string
myNode = "<" + aryEleNodes[aryEleNodes.Count-1].ToString() + ">" +
string strObj = "true";
Session["OkToRecreateControls"] = strObj;
Session["tempArray"] = aryTxtNodes;
catch(Exception exc)
span2.InnerHtml = "Error...loading xml tags </b><br>"+ exc.ToString();

public void CreateDynamicControls()
string strOkToRecreateControls =
plhXmlContent.EnableViewState = true;

if (strOkToRecreateControls != null)
ArrayList aryNodes = (ArrayList)Session["tempArray"];

for (int createControl=0; createControl < aryNodes.Count;
literal = new LiteralControl();
literal.ID = "ltrId" + (createControl + 1).ToString();

ddlXmlTagList = new DropDownList();
ddlXmlTagList.ID = "ddlId" + (createControl + 1).ToString();
ddlXmlTagList.AutoPostBack = true;
ddlXmlTagList.EnableViewState = true;
ddlXmlTagList.SelectedIndexChanged += new

string strObj = "true";
Session["OkToAddContent"] = strObj;
Session["OkToRecreateControls"] = strOkToRecreateControls;

public void AddContentToDynamicControls()
string strOkToAddContent = (string)Session["OkToAddContent"];

if (strOkToAddContent != null)
ArrayList aryNodes = (ArrayList)Session["tempArray"];

for (int addContent = 0; addContent < aryNodes.Count; addContent++)
string ltrName = "ltrId" + (addContent + 1).ToString();
string ddlName = "ddlId" + (addContent + 1).ToString();

LiteralControl ltl =
(LiteralControl)this.FindControl("plhXmlContent"). FindControl(ltrName);
DropDownList ddl =
(DropDownList)this.FindControl("plhXmlContent").Fi ndControl(ddlName);

ltl.Text = "<p><strong>Xml Tag " + (addContent + 1) + ":</b>";

for(int addItem = 0;addItem < aryNodes.Count;addItem++)

ddl.SelectedIndex = addContent;

private void btnSave_Click(object sender, System.EventArgs e)

public void MsgBox(string strMsg)
string alertScript;

alertScript = "<script language=JavaScript> alert('" + strMsg +"');
</script" +">";

if (!IsClientScriptBlockRegistered("alert"))
this.RegisterClientScriptBlock("alert", alertScript);

public string ReadDropDownList(object sender, System.EventArgs e)
DropDownList ddl = (DropDownList)sender;
if ( ddl != null )
if ( ddl.SelectedIndex >= 0 )
string strSelection = "Selected Control Id : " + ddl.ID.ToString();
strSelection+= "\\nSelected Text : " + ddl.SelectedItem.Text.ToString();

return strSelection;

*** Sent via Developersdex http://www.developersdex.com ***
Nov 17 '05 #1
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