Some Information from InClass Exercise 2

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Some Information from In-Class Exercise 2

• Out of 35 submissions, 15 submitted the wrong
  file or did not name the file correctly.
• The instruction requests the file for the aspx
  Web form (i.e., the file with the .aspx file
  extension) be submitted.
• Some submitted the vb code file (the file with
  the .aspx.vb extension)
• Some submitted the .sln file.

Question Is there confusion about the file
structure in a Web application?
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Some Advice

• Keep up with your reading. That will help you
  get through in-class exercise easier.
• Treat programming instruction as end-user
  requirements. Part of MIS workers
  professionalism is to precisely implement user
  requirements.
• MIS has its technical side that requires us to be
  accurate and logical. If something does not work
  or seem complicated, there must be a reason. Be
  a good detective.

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How to be a good detective?

• Object-oriented programming relies mainly on
  objects (i.e., classes in VB terminology) to
  perform its tasks.
• The more objects you know about, the more
  effective you will be.
• To know objects, you need to know how to use
  their properties, behaviors (i.e., functions),
  and events.
• You also need to master the three basic
  processing constructs sequential, selection, and
  looping.
• Can conceptualize/visualize abstract data types
  such as a sorted list being constructed using
  basic data types such as integer, string, etc.
• Also useful is standalone functions CType( ),
  FormatCurrency( ), CDec( )

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How to Know More Objects?

• By seeing how others use them, e.g., application
  examples in your books
• By checking out the help files about objects.

Lets start by checking out the following
classes, which you need to use in your first
homework assignment gtgt DropDownList gtgt
AccessDataSource gtgt DataView gtgt
DataRowView gtgt HttpSessionState, Session gtgt
SortedList
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DropDownList

• Some Properties AutoPostBack, DataSourceID,
  DataFieldText, DataValueField, Items,
  SelectedItem, SelectedIndex, SelectedValue
• Some Methods DataBind( ), ToString

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AccessDataSource

• Some Properties ID, ConnectionString, DataFile,
  SelectCommand, DeleteCommand, InsertCommand,
  UpdateCommand
• Some Methods Select, Update, Insert, Delete

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DataView

• Definition Represents a databindable, customized
  view of a DataTable for sorting, filtering,
  searching, editing, and navigation.
• Some Properties Count, Item, RowFilter, Sort,
  Table
• Indexing DataView1.Item(integer) or DataView1
  (integer)
• Some Methods AddNew, ToString, ToTable, Delete,
  Find, FindRows, GetType

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DataRowView

• Some Properties Item, Row
• Indexing
• DataRowView1.Item (integer)
• DataRowView1 (integer)
• DataRowView1.Item (Table Column Name)
• DataRowView1 (Table Column Name)
• DataRowView1.Row (integer)
• Some Methods Delete, GetType, ToString

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HttpSessionState, Session

• ASP.NET provides session-state management to
  enable you to store information associated with a
  unique browser session across multiple requests.
• You can store a collection of values referenced
  by a key name or by numerical index.
• Access to session values and functionality is
  available using the HttpSessionState class
• HttpSessionState class is accessible through the
  Session property of the current HttpContext, or
  the Session property of the Page.

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HttpSessionState, Session

• Some Properties Count, IsCookieless, Item, Keys,
  SessionID
• Some Methods
• Add (object name, object value)
• Session(object name) object value
• Remove (key value)
• RemoveAt (integer)
• RemoveAll

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SortedList An Abstract Data Type

• A collection of key-and-value pairs that are
  sorted by the keys and are accessible by key and
  by index.
• Each entry in a SortedList is of the data type
  Dictionary Entry, i.e. (key, value)
• The key is the identifier used to retrieve the
  value.
• The value can be a simple data type like a string
  or a complex data type like a user-defined class

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SortedList An Abstract Data Type

• Some Properties Count, Keys, Values, Item
• Indexing
• SortedList1.Item (key value or integer)
• SortedList1 (key value or integer)
• Some Methods Add, ConstainsKey, ConstainsValue,
  IndexOfKey, IndexOfValue, GetKey (integer),
  Remove, RemoveAt, RemoveAll

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SortedList An Abstract Data Type
Public Class Product Public ProductID As
String Public Name As String Public
ShortDescription As String Public
LongDescription As String Public UnitPrice As
Decimal Public ImageFile As String End Class
The shopping cart (Cart) defined in the Order
page is a sortedlist. Each entry
(DictionaryEntry) in the Cart has a pair of key
and value. The Key is the ProductID, and the
Value is the user-defined class "CartItem". The
Cart is stored in Session.
Public Class CartItem Public Product As
Product Public Quantity As Integer End Class
Inside the Shopping Cart Key Value ProductID Car
tItem (Product (ProductID, Name),
Quantity) ProductID CartItem (Product (ProductID,
Name), Quantity)
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The shopping cart or the session looks like this
Entry 1
Entry 2