how do i fetch the id of a dynamically created web control

Question

I have been trying to fetch ids of dynamically created dropdownlists(during Page_Load) ,which are in a table, and then find the selected values in those dropdownlists and store these values a table or GridView on button click.This is how i assigned id's(in Page_Load event)

         drd.ID = "dbaseid" + rowctr; 
         drd1id[rowctr]=drd1.ID;

rowctr is the index variable to assign unique id to each dropdown.

How do i fetch the ids from Page_Load . I tried storing the id in an array and then using session variable:

         drdid[rowctr]=drd.ID;
         drd1id[rowctr]=drd1.ID;
         Session["drditem"]=drditem;
         Session["drd1item"]=drd1item;

and then tried to fetch the ids in buttonclick event function:

         drdid=(string[])Session["drdid"];           
         drd1id=(string[])Session["drd1id"];
         string[] a =new string [50];
         for(int i =0;i<noodropdowns;i++)
         {
           a=drd1id[i];
           a.selectedindex//doesnt work !!
         }

Is there a way to get the real ids and then work on them ? I m new to asp.net , My apologies if it sounds noob ish .. thanks in advance.

Answer 1

Found success ,found the dropdowns and saved the selected values in a table .Every time a value from a drop down is selected it is changed in the table as well.Here is the code..

     using System.Collections.Generic;
     using System.Linq;
     using System.Web;
     using System.Web.UI;
     using System.Web.UI.WebControls;
     using System.IO;
     using System.Data;
     using System.Data.SqlClient;
     using System.Data.OleDb;
     using System.Collections;
     using System.Web.Security;
     using System.Text;
     using System.Configuration;
     using System.Web.SessionState;
     using System.Windows;

     public partial class Default2 : System.Web.UI.Page
     {
     Table tblRecipients = new Table();
     DropDownList drd = new DropDownList();
     DropDownList drd1 = new DropDownList();
     protected void Page_Init(object sender, EventArgs e)
{
    DataTable dtt = (DataTable)Session["griddata"];
    int n = dtt.Columns.Count;
    string[] drd1item = new string[n];
    string[] excel = new string[n];
    for (int i = 0; i < dtt.Columns.Count; i++)
    {
        excel[i] = dtt.Columns[i].ColumnName;
    }
    Session["exceldata"] = excel;

    ////saving sql database column names in an array variable
    DataTable dtt1 = (DataTable)Session["dbasecolumns"];
    int l = dtt1.Columns.Count;
    string[] drditem = new string[l];
    string[] sqlcolumn = new string[l];
    for (int j = 0; j < dtt1.Columns.Count; j++)
    {
        sqlcolumn[j] = dtt1.Columns[j].ColumnName;
    }
    Session["sqlcolumn"] = sqlcolumn;
    Session["l"] = l;

    //Table Creation
    Table mytable = new Table();
    mytable.Visible = true;
    mytable.GridLines = GridLines.Both;
    TableHeaderRow th = new TableHeaderRow();
    TableHeaderCell thc = new TableHeaderCell();
    TableHeaderCell thc1 = new TableHeaderCell();

    mytable.Rows.Add(th);
    Label lbl1 = new Label();
    Label lbl2 = new Label();

    lbl1.Text = "Database";
    lbl2.Text = "Excel";

    thc.Controls.Add(lbl1);
    thc1.Controls.Add(lbl2);
    th.Cells.Add(thc);
    th.Cells.Add(thc1);


    for (int rowctr = 0; rowctr < sqlcolumn.Length; rowctr++)
    {
        TableCell mycell = new TableCell();
        TableCell mycell1 = new TableCell();

        for (int cellctr = 0; cellctr < 1; cellctr++)
        {
            //dropdown with database columns
            DropDownList drd = new DropDownList();
            drd.Items.Insert(0, new ListItem("--Select--", "0"));
            drd.ID = "dbaseid" + rowctr;
            for (int i = 0; i < sqlcolumn.Length; i++)
            {
                drd.Items.Add(sqlcolumn[i]);
                drditem[i] = sqlcolumn[i];
            }
            // drd.SelectedIndexChanged+=new EventHandler(drd1_SelectedIndexChanged);


            //dropdown with excel columns
            DropDownList drd1 = new DropDownList();

            drd1.ID = "excelid" + rowctr;

            for (int j = 0; j < excel.Length; j++)
            {
                drd1.Items.Add(excel[j]);
                drd1item[j] = excel[j];
            }
            // drd1.SelectedIndexChanged +=new EventHandler (drd1_SelectedIndexChanged);
            //session variable to store dropdown elements in an array




            //Table cells and rows addition 
            TableRow myrow = new TableRow();
            mycell.Controls.Add(drd);
            mycell1.Controls.Add(drd1);
            myrow.Cells.Add(mycell);
            myrow.Cells.Add(mycell1);
            mytable.Rows.Add(myrow);
            mytable.BorderStyle = BorderStyle.Solid;
        }
    }

    DynamicControlsHolder.Controls.Add(mytable);
}

     protected void Button1_Click(object sender, EventArgs e)
{
    Table mytable = new Table();
    mytable.GridLines = GridLines.Both;
    string s;
    foreach (Control ctl in DynamicControlsHolder.Controls)
    {
        if (ctl is Table)
        {
            Table tblnew = ctl as Table;
            {
                foreach (Control ctrl in tblnew.Controls)
                {
                    if (ctrl is TableRow)
                    {
                        TableRow trow = new TableRow();
                        TableRow tblrow = ctrl as TableRow;
                        {

                            foreach (Control cntrl in tblrow.Controls)
                            {
                                if (cntrl is TableCell)
                                {
                                    TableCell tcell = new TableCell();
                                    TableCell tblcell = cntrl as TableCell;
                                    {
                                        foreach (Control cntrol in tblcell.Controls)
                                        {
                                            if (cntrol is DropDownList)
                                            {
                                                DropDownList myddr = cntrol as DropDownList;
                                                if (cntrol != null)
                                                {




                                                    s = myddr.SelectedItem.Text;
                                                    tcell.Text = s;


                                                }
                                            }

                                        }

                                    }
                                    trow.Cells.Add(tcell);
                                }
                            }

                        }

                        mytable.Rows.Add(trow);  
                    }
                }
            }
        }
    }
    DynamicControlsHolder.Controls.Add(mytable);
}

}

Answer 2

Hey if you are trying to loop over all the drop down list in the GridView and get the drop down list ?

//Add the drop down as following in page load
drd.ID = "dbaseid"; //do not add dynamic id other wise you will not able to find it. 
                    //It client id would be different based upon its position in DOM


//loop over gridview row and get the control as following

foreach (GridViewRow row in grid.Rows)
{
   var ddl = row.FindControl("dbaseid") as DropDown;  
  //do what ever with the drop down 
}

Answer 3

You mentioned that the dynamically created dropdownlists are in a table. I think Anand was referring to that table, not to the GridView you wish to populate with the values of the dropdownlists. So, you could try to loop over the rows of the table and get the dropdownlist ids.