Possible to remove tag item from Literal

Question

I have the below code

namespace WebApplication3
{
    public partial class WebForm2 : System.Web.UI.Page
    {
        class Customer
        {
            public Customer(int id, string fName)
            {
                ID = id;
                FirstName = fName;
            }

            public int ID { get; set; }
            public string FirstName { get; set; }
        }

        private List GetCustomerNames()
        {
            // Add Customers to list - this is essentially coming from a database
            List Names = new List();
            Names.Add(new Customer(1, "Name 1"));
            Names.Add(new Customer(2, "Name 2"));
            Names.Add(new Customer(3, "Name 3"));
            Names.Add(new Customer(4, "Name 4"));

            return Names;
        }

        private void DropdownNames()
        {
            // Set the dropdown
            ddlName.DataSource = GetCustomerNames();
            ddlName.DataTextField = "FirstName";
            ddlName.DataValueField = "ID";
            ddlName.DataBind();
        }

        private void SetNameHTML(List Names)
        {
            // The below code would set the literal control with the values coming from the list along with custom span so the design would be correct
            Int32 Count = 0;
            lit1.Text = string.Empty;

            foreach (Customer c in Names)
            {
                if (Count == 0)
                {
                    // IF first element then set active class so correct style is applied
                    lit1.Text += string.Format("{1} 
", c.FirstName, c.ID);
                    spName.InnerText = c.FirstName;
                }
                else
                {
                    // Other non selected items - Note no active listed in the class
                    lit1.Text += string.Format("{1} 
", c.FirstName, c.ID);
                }

                Count += 1;
            }
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                DropdownNames();
                SetNameHTML(GetCustomerNames());
            }

        }

        protected void ddlName_SelectedIndexChanged(object sender, EventArgs e)
        {
            // Get customer names again as the list would be empty if the SetNameHTML is removed
            var CustomerNames = GetCustomerNames();
            SetNameHTML(CustomerNames);
            // Get a single customer to set the correct class (square active)
            var CustName = CustomerNames.Where(cid => cid.ID == Convert.ToInt32(ddlName.SelectedValue)).FirstOrDefault();
            spName.InnerText = ddlName.SelectedItem.Text;

            // += on lit1.Text so that the span list is not empty. 
            // If i remove the lin SetNameHTML(CustomerNames); above then the list is empty
            lit1.Text = string.Format("{1} 
", CustName.FirstName, CustName.ID);
        }
    }
}

ASPX code

I'm using the literal control so i can add the relevant span depending on the number of names found. Please note ive stripped out majority of the CSS JS which is why it may look plain.

When i select an item from the dropdown it adds the item again (if you run the above code you will know what i mean)

Note my comments and why i have done what i have.

Heres the view source of when the page loads and then once i select an item

Load

First item selected

I know why this is happening but im not sure how to go about this. What i want to do is not add the selected item to the list again but since im using a literal control i dont know how to remove it or if there is a better way to go about this?

Martin Parenteau · Accepted Answer

You can replace the Literal control by a PlaceHolder:

And add ASP.NET Label controls in it, which are rendered as span elements in the HTML output, or ASP.NET Panel controls, which are rendered as div elements.

That way, you will work with controls instead of inserting raw HTML code in a Literal, which is more difficult to manage.

UPDATE

The new Labels must be added to the PlaceHolder on each postback, not inside an if (!IsPostBack) conditional block. Each ID must also be unique (or you can leave the ID property empty). I mention it because I see several span elements with the ID spname in your markup sample.

In a simple case, it would look like this:

private int labelSuffix = 0;

protected void Page_Load(object sender, EventArgs e)
{
    Label lbl = new Label();
    lbl.ID = string.Format("span_{0}", labelSuffix++);
    lbl.Attributes.Add("data-value", "Name 1");
    lbl.CssClass = "square";
    lbl.Text = "1";
    ph1.Controls.Add(lbl);
    ...
}

The Label can then be retrieved in another event handler:

protected void btnPostBack_Click(object sender, EventArgs e)
{
    // By the ID of the control
    Label lbl = ph1.FindControl("MyLabel") as Label;
    lbl.Text = "With some new text";

    // Or by looping on the controls collection
    foreach (Label lbl in ph1.Controls)
    {
        lbl.Text = "And another text";
    }
}

Possible to remove tag item from Literal

Answers (2)

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