Chapter 3 Slides asp

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Murachs ASP.NET 3.5/C#, C3 2008, Mike Murach & Associates, Inc. Slide 1

Chapter 3

How to develop

a multi-pageweb application


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Objectives

Applied Given the specifications for a multi-page web application that uses anAccess data source to get data, design, code, and test the application.

To transfer to another page within a web application, be able to usethe Transfer method, the Redirect method, or cross-page posting.

To refer to pages or other files within an application, be able to useeither absolute or relative URLs.

Knowledge

Describe the contents of these special folders for ASP.NET

applications: App_Code and App_Data. Describe two ways that you can use an existing class with a new webapplication.


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Objectives (continued) In general terms, describe the procedure for renaming a web form fileas well as the class that contains the code for the web form.

Distinguish between the Transfer method of the HttpServerUtilityclass, the Redirect method of the HttpResponse class, and cross-page

posting.

Distinguish between absolute and relative URLs.

Describe an Access data source.

In general terms, explain how the AccessDataSource, DataView, andDataRowView classes can be used to get data from a data source.

Describe how session state objects, session IDs, and cookies are used

to track the state of each user of a web application.


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The design of the Order page


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The design of the Cart page


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The Solution Explorerfor the Shopping Cart application


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Special folders used by the Shopping Cart

application App_Code App_Data

User folder used by the Shopping Cart application

Images


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Adding a new class to the App_Code folder


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Two ways to use an existing class

Add the class to your web site by copying it from another project. Add a reference to the class library that contains the class youwant.


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Adding a new web form


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A web form file being renamedin the Solution Explorer window


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To rename the class for a renamed file

Change the name on the Class statement for the form. Change the name in the Inherits attribute of the Page directive in

the aspx code for the form.


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Two methods for displaying another page

The Transfer method of the HttpServerUtility class The Redirect method of the HttpResponse class

Code that transfers control to another pageServer.Transfer("Cart.aspx")

Code that redirects the client to another pageResponse.Redirect("Cart.aspx")


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Properties and methods for cross-page posting

The aspx code for a button

Code that retrieves data from the previous page protected void Page_Load(object sender, EventArgs e)

{

if (PreviousPage != null){TextBox txtQuantity = (TextBox)

PreviousPage.FindControl("txtQuantity");lblQuantity.Text = txtQuantity.Text;

}}


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Statements that use absolute URLsResponse.Redirect("http://www.murach.com/Default.aspx")Response.Redirect("http://www.murach.com/Books/Search.aspx")


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Statements that use relative URLsthat are based on the current directory

Response.Redirect("Checkout.aspx")Response.Redirect("Login/Register.aspx")


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Statements that use relative URLs that navigateup the directory structure

Response.Redirect("../Register.aspx")Response.Redirect("../../Register.aspx")Response.Redirect("/Register.aspx")Response.Redirect("/Login/Register.aspx")


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Server control attributes that use URLs that are

based on the root directory of the current web sitePostBackUrl="~/Cart.aspx"ImageUrl="~/Images/banner.jpg"


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The Configure Data Source dialog box


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The Configure Data Source wizard


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The aspx code for an Access data source control


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The Data Source Configuration Wizard dialog box


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The aspx code for a bound drop-down list


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Getting product information from the data sourceDataView productsTable = (DataView)

AccessDataSource1.Select(DataSourceSelectArguments.Empty); productsTable.RowFilter =

"ProductID = '" + ddlProducts.SelectedValue + "'";DataRowView row = (DataRowView) productsTable[0];Product p = new Product();

p.ProductID = row["ProductID"].ToString();

p.Name = row["Name"].ToString(); p.ShortDescription = row["ShortDescription"].ToString(); p.LongDescription = row["LongDescription"].ToString(); p.UnitPrice = (decimal) row["UnitPrice"]; p.ImageFile = row["ImageFile"].ToString();

Objects used DataView

DataRowView


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How ASP.NET maintains the state of a session

Server First HTTP request:The browser requests a page.

ASP.NET creates a sessionstate object and assigns an IDfor the session.

Client

Web server

First HTTP response:The server returns therequested page along with the

session ID.

Next HTTP request:The browser requests another page. The server uses the sessionID included in the request to

associate the browser with thecorrect session state object.

Web server

Web server Browser

Browser

Browser Session ID

Session ID


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Session state concepts

For each user session, ASP.NET creates a session state object . The session state object includes a session ID thats sent back to

the browser as a cookie .

The browser automatically returns the session ID cookie to theserver with each HTTP request.

The session ID lets the server find the right session state object. The session state object can be used to store and retrieve items

that can be used by any of the pages in the application.


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Typical uses for session state

To keep information about the user , such as the users name orwhether the user has registered.

To save objects the user is working with , such as a shoppingcart or a customer record.

To keep track of pending operations , such as what steps the

user has completed while placing an order.


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Common properties of the HttpSessionState class SessionID

Count

Common indexer of the HttpSessionState class [name]

Common methods of the HttpSessionState class Add(name, value)

Clear

Remove(name)


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Adding to or updating a session state itemSession["Cart"] = cart;

Another way to add or update a session state itemSession.Add("Cart", cart);

Retrieving the value of a session state itemSortedList cart = (SortedList) Session["Cart"];

Removing an item from session stateSession.Remove("Cart");


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Retrieving the value of a session state item from aclass that doesnt inherit System.Web.UI.Page

SortedList cart = (SortedList)HttpContext.Current.Session["Cart"];


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The code for the Product classusing System;using System.Configuration;using System.Data;using System.Linq;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Xml.Linq;

/// /// Summary description for Product///

public class Product{ public string ProductID; public string Name; public string ShortDescription; public string LongDescription; public decimal UnitPrice; public string ImageFile;

}


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The code for the CartItem class

using System;using System.Configuration;using System.Data;using System.Linq;using System.Web;using System.Web.Security;using System.Web.UI;

using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Xml.Linq;


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The code for the CartItem class (cont.)

/// /// Summary description for CartItem///

public class CartItem{

public Product Product; public int Quantity;

public string Display(){

string displayString =Product.Name + " (" + Quantity.ToString()+ " at " + Product.UnitPrice.ToString("c")+ " each)";

return displayString;}

}


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The aspx file for the Order page (Order.aspx)

Chapter 3: Shopping Cart

.style1{

width: 250px;}.style2{

width: 20px;}


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The aspx file for the Order page (cont.)


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The code-behind file for the Order page(Order.aspx.cs)

using System;using System.Collections;using System.Configuration;using System.Data;using System.Linq;using System.Web;using System.Web.Security;

using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Xml.Linq;

public partial class Order : System.Web.UI.Page

{ private Product selectedProduct;


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The code-behind file for the Order page (cont.) protected void Page_Load(object sender, EventArgs e){

if (!IsPostBack)ddlProducts.DataBind();

selectedProduct = this.GetSelectedProduct();lblName.Text = selectedProduct.Name;lblShortDescription.Text

= selectedProduct.ShortDescription;lblLongDescription.Text

= selectedProduct.LongDescription;lblUnitPrice.Text

= selectedProduct.UnitPrice.ToString("c");imgProduct.ImageUrl = "Images/Products/"

+ selectedProduct.ImageFile;}


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The code-behind file for the Order page (cont.) private Product GetSelectedProduct(){

DataView productsTable = (DataView)

AccessDataSource1.Select(DataSourceSelectArguments.Empty);

productsTable.RowFilter ="ProductID = '" + ddlProducts.SelectedValue+ "'";

DataRowView row = (DataRowView) productsTable[0];

Product p = new Product(); p.ProductID = row["ProductID"].ToString(); p.Name = row["Name"].ToString(); p.ShortDescription =

row["ShortDescription"].ToString(); p.LongDescription =

row["LongDescription"].ToString();

p.UnitPrice = (decimal) row["UnitPrice"]; p.ImageFile = row["ImageFile"].ToString();

return p;}


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The code-behind file for the Order page (cont.) protected void btnAdd_Click(object sender, EventArgs e){

if (Page.IsValid){

CartItem item = new CartItem();item.Product = selectedProduct;item.Quantity =

Convert.ToInt32(txtQuantity.Text);this.AddToCart(item);Response.Redirect("Cart.aspx");

}}


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The code-behind file for the Order page (cont.) private void AddToCart(CartItem item){

SortedList cart = this.GetCart();

string productID = selectedProduct.ProductID;if (cart.ContainsKey(productID)){

CartItem existingItem =(CartItem) cart[productID];

existingItem.Quantity += item.Quantity;}

elsecart.Add(productID, item);

}

private SortedList GetCart(){if (Session["Cart"] == null)

Session.Add("Cart", new SortedList());

return (SortedList) Session["Cart"];}

}


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The aspx file for the Cart page (Cart.aspx)

Chapter 3: Shopping Cart

.style1 { width: 286px;

height: 153px;}.style2 {

height: 153px;}


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The aspx file for the Cart page (cont.)

Your shopping cart:


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The aspx file for the Cart page (cont.)


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The code-behind file for the Cart page(Cart.aspx.cs)

using System;using System.Collections;using System.Configuration;using System.Data;using System.Linq;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Xml.Linq;

public partial class Cart : System.Web.UI.Page{

private SortedList cart;


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The code-behind file for the Cart page (cont.) protected void Page_Load(object sender, EventArgs e){

this.GetCart();if (!IsPostBack)this.DisplayCart();

}

private void GetCart(){if (Session["Cart"] == null)

Session.Add("Cart", new SortedList());

cart = (SortedList) Session["Cart"];}

private void DisplayCart(){lstCart.Items.Clear();CartItem item;foreach (DictionaryEntry entry in cart)

{ item = (CartItem) entry.Value;lstCart.Items.Add(item.Display());

}}


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The code-behind file for the Cart page (cont.) protected void btnRemove_Click(

object sender, EventArgs e){

if (cart.Count > 0){if (lstCart.SelectedIndex > -1){

cart.RemoveAt(lstCart.SelectedIndex);this.DisplayCart();

}

else{lblMessage.Text = "Please select the item "

+ "you want to remove.";}

}}


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The code-behind file for the Cart page (cont.) protected void btnEmpty_Click(

object sender, EventArgs e){

cart.Clear();lstCart.Items.Clear();}

protected void btnCheckOut_Click(object sender, EventArgs e){

lblMessage.Text = "Sorry, that function "

+ "hasn't been implemented yet.";}

}


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Sorted list concepts Each item in a SortedList object is a DictionaryEntry object.

A DictionaryEntry object consists of a key and value.

The Value property of a DictionaryEntry object returns an Objecttype so it must be cast to the proper type before it can be stored.

Date post:	04-Jun-2018
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Chapter 3 Slides asp

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