How to return selected items from checkboxlist control in asp.net

Question

I am trying to return in a string the selected items from a dynamically bound checkbox list control with no luck. I'm hoping someone can help. In my code behind file I am conencting to a class called users and building a datatable. I then bind the data table to the cblist control

        private void populateUserList() //called on page load
    {

            SubmitOptions mySubmission = new SubmitOptions(juris, rptType, tmplName);

            if (mySubmission.Users.Count == 0)
            {
                lbl_juris.Visible = false;
                cb_selectUser.Visible = false;
                lbl_AlertMsg.Visible = true;
                btnSelect.Visible = false;
                lbl_AlertMsg.Text = "No supervisors listed for jursidiction: " + juris.ToString();
            }
            else
            {

                dt.Columns.Add("Users");
                for (int i = 0; i < mySubmission.Users.Count(); i++)
                {
                    DataRow dr = dt.NewRow();
                    dr["Users"] = mySubmission.Users[i];
                    dt.Rows.Add(dr);
                }

                cb_selectUser.DataSource = dt;
                cb_selectUser.DataBind();
            }

     }

Within the main aspx file I have the control defined as:

<asp:CheckBoxList ID="cb_selectUser"
       Width="400px" 
       Height="100%"
       AutoPostBack="false"  
       runat="server"  
       CellPadding="2"  
       CellSpacing="5"
       DataTextField="Users" 
       DataValueField="Users"
        >
        </asp:CheckBoxList>

I have tried the following code where i itterate through the list but this only seems to work if I hard code values into the Checkboxt list as listitems.

 protected void btn_returnUserList(object sender, System.Web.UI.ImageClickEventArgs e)
    {
        for (int i = 0; i < cb_selectUser.Items.Count; i++)
        {
            if (cb_selectUser.Items[i].Selected)
            {

                selectedUsers += cb_selectUser.Items[i].Text;
            }
        }

The list populates fine and all I want to do is return in a string all selected users from the checkbox list control.

As I said if I hard code the item values into the control the above code works and I can see the selected items in the string however removing the itemslist tags and switching over to a binding nothign happens. The above method counts the entire number of returns but nothing selected is ever returned.

Any tips or suggestions as to what I am missing would be greatly appreciated.

Answer 1

Can you use the sender to retrieve your selected items and see if you get the same result?

protected void btn_returnUserList(object sender, System.Web.UI.ImageClickEventArgs e)
{
    CheckBoxList cbl = sender as CheckBoxList;
    if (sender == null) {
        throw new Exception("Sender is not a CheckBoxList");
    }

    for (int i = 0; i < cbl.Items.Count; i++)
    {
        if (cbl.Items[i].Selected)
        {
            //  Also, set a breakpoint here... are you hitting this line?
            selectedUsers += cbl.Items[i].Text;
        }
    }

Also, test to see if you're getting into the block for selected items... are they registering as selected, but not getting the text back? Or do the items not show up as selected in the first place?

Answer 2

Are you sure populateUserList() is only being called once? (i.e. not on postback as well). If it gets called twice the selected items collection will be blank.

protected void Page_Load(object sender, EventArgs e)
{
  if(!IsPostBack)
  {
    populateUserList();
  }
}

Answer 3

You need to ensure your checkboxlist has databound before trying to retrieve values from it.

Answer 4

here is complete code of page working exactly as you want it. just add a CheckboxList to form name it to list1, add a button name it to btn and add a label and name it lbl.

protected void Page_Load(object sender, EventArgs e)
        {
            if(!IsPostBack)
            {
                var dt = new DataTable();
                dt.Columns.Add("Users");

                const string str = "User {0}";
                for(var i=1;i<=10;i++)
                {
                    //var r = dt.NewRow();
                    //r.ItemArray=new object[]{string.Format(str,i)};
                    dt.Rows.Add(new object[] {string.Format(str, i)});
                }
                list1.DataSource = dt;
                list1.DataTextField = "Users";
                list1.DataBind();
            }
        }

        protected void btn_Click(object sender, EventArgs e)
        {
            var s = list1.Items.Cast<ListItem>()
                   .Where(item => item.Selected)
                   .Aggregate("", (current, item) => current + (item.Text + ", "));
            lbl.Text = s.TrimEnd(new[] {',', ' '});
        }

Answer 5

Try out this one:-

    foreach (ListItem li in cb_selectUser.Items)

   {
       //Your Code
   }