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HttpSessionState.Add Method

Adds a new item to the session-state collection.

Namespace: System.Web.SessionState
Assembly: System.Web (in system.web.dll)

public void Add (
	string name,
	Object value
public void Add (
	String name, 
	Object value
public function Add (
	name : String, 
	value : Object
Not applicable.



The name of the item to add to the session-state collection.


The value of the item to add to the session-state collection.

If the name parameter refers to an existing session state item, the existing item is overwritten with the specified value.

The following example shows how to store values in session state by using the Add method. It also shows how to remove values in session state by using the Remove method. A Repeater control is used to display the contents session state on the Web page. The GetEnumerator method is used to iterate through the session-state collection and populate the Repeater control.

Security noteSecurity Note:

This example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview (Visual Studio).

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">

<script runat="server">

    protected void Button1_Click(object sender, EventArgs e)
        // If both name and value are specified
        // use the Add method to add the item to session-state.
        if (!String.IsNullOrEmpty(TextBox1.Text) &
            string itemName = Server.HtmlEncode(TextBox1.Text);
            string itemValue = Server.HtmlEncode(TextBox2.Text);
            Session.Add(itemName, itemValue);
            // Refresh the Repeater control.

    protected void RefreshRepeater()
        // Use the GetEnumerator method to 
        // iterate through the session-state.
        ArrayList values = new ArrayList();
        System.Collections.IEnumerator ie = Session.GetEnumerator();
        string currentSessionItemName;
        while (ie.MoveNext())
            currentSessionItemName = (string)ie.Current;
            values.Add(new SessionDataDisplay(currentSessionItemName,
        // Bind values ArrayList to Repeater control.
        Repeater1.DataSource = values;
    public class SessionDataDisplay
        private string _name;
        private string _value;

        public SessionDataDisplay(string name, string value)
            this._name = name;
            this._value = value;
        public string Name
            get { return _name; }
        public string Value
            get { return _value; }

    protected void Repeater1_ItemCommand(object source, RepeaterCommandEventArgs e)
        // Determine which item to remove and
        // use the Remove method to remove it.
        RepeaterItem itemToRemove = e.Item;
        string sessionItemToRemove = 
        // Refresh the Repeater control.

<html xmlns="" >
<head runat="server">
    <title>HttpSessionState Example</title>
    <form id="form1" 
        <asp:TextBox ID="TextBox1"
        <br />
        <asp:TextBox ID="TextBox2" 
        <asp:Button ID="Button1" 
                    Text="Add" />
        <br />
        <asp:Repeater ID="Repeater1" runat="server" OnItemCommand="Repeater1_ItemCommand">
             <br />
                SessionState Item Name:  
                <asp:Label ID="Label1" 
                           Text='<%# DataBinder.Eval(Container.DataItem, "Name") %>'/>,
                SessionState Item Value: 
                <asp:Label ID="Label2" 
                           Text='<%# DataBinder.Eval(Container.DataItem, "Value") %>'/>
                <asp:Button ID="RemoveItem" 
                            runat="server" />

Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0