Transferring Information Between Pages

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TRANSFERRING INFORMATION BETWEEN PAGES 

Cross Page Posting

A cross-page postback is a technique that extends the postback mechanism youve already

learned about so that one page can send the user to another page, complete with all theinformation for that page.

Query String

The query string is the portion of the URL after the question mark. In this case, it defines a

single variable named q, which contains the string organic+gardening.

Another common approach is to pass information using a query string in the URL.This

approach is commonly found in search engines. For example, if you perform a search on the

Google website, youll be redirected to a new URL that incorporates search Parameters.

QueryString1.aspx.CS 

protected void Page_Load(object sender, EventArgs e){

if (!this.IsPostBack){

lstItems.Items.Add("A");lstItems.Items.Add("B");lstItems.Items.Add("C");

}}protected void Button1_Click(object sender, EventArgs e){

if (lstItems.SelectedIndex == -1){

// Error Message}else{

string url = "~/Topics/Transferring Information/QueryString2.aspx?";//url += "Item=" + lstItems.SelectedItem.Text;string X = lstItems.SelectedItem.Text;string Y = chkDetails.Checked.ToString();url = url + "Item=" + X + "&" + "Mode=" + Y;Response.Redirect(url);

}}

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QueryString2.aspx.CS 

protected void Page_Load(object sender, EventArgs e){

lblInfo.Text = "Item: " + Request.QueryString["Item"] + "<br/>" +"Selected:"+ Request.QueryString["Mode"];

}

// ³?´ needed at page URL

//Items and Mode are query stringname 

Cookies

Cookies are small files that are created on the clients hard drive (or, if theyre temporary,

in the web browsers memory). One advantage of cookies is that they work transparently

without the user being aware that information needs to be stored. They also can be easily

used by any page in your application and even be retained between visits, which allows for

truly long-term storage.

Reference: using System.Net;

CookieExample.aspx.cs

protected void Page_Load(object sender, EventArgs e){

HttpCookie cookie = Request.Cookies["Preferences1"];if (cookie == null){

lblWelcome.Text = "<b>Unknown Customer</b>";}else{

lblWelcome.Text = "Welcome : " + cookie["Name"];}

}

protected void cmdStore_Click(object sender, EventArgs e)

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{// Check for a cookie, and only create a new one if// one doesn't already exist.HttpCookie cookie = Request.Cookies["Preferences1"];if (cookie == null){

cookie = new HttpCookie("Preferences1");}else{}cookie["Name"] = txtName.Text;cookie.Expires = DateTime.Now.AddYears(1);Response.Cookies.Add(cookie);lblWelcome.Text = "<b>Cookie Created.</b><br /><br />";lblWelcome.Text += "New Customer: " + cookie["Name"];

}

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Session State 

Session state management is one of ASP.NETs premiere features. It allows you to storeany type of data in memory on the server. The information is protected, because it is never

transmitted to the client, and its uniquely bound to a specific session. Every client that accesses the application has a different session and a distinct collection of information.

Session.aspx.cs

protected void Button1_Click(object sender, EventArgs e){

Session["txtvalue"] = TextBox1.Text;Response.Redirect("Session2.aspx");

}

Session2.aspx.cs

protected void Page_Load(object sender, EventArgs e){

Label1.Text="<b>Welcome "+Session["txtvalue"];} 

Session.aspx Session2.aspx