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LECTURE 7
Managing Multiple-Form Applications Writing
scripts with multiple screens
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Objectives

• To understand what are multiple-form Web sessions
• To learn how to use hidden fields to build
  multiple-form user sessions
• To learn how to use browser cookies to track data
  about the user
• To learn how to use PHP session functions and how
  to use them to track data about the user

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What Are Multiple-Form Web Sessions?

• A multiple-form Web session leads the user
  through a series of HTML forms that work together
  and pass data from form to form.
• E.g., a shopping cart or on-line survey.

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Example Multiple Screen Session
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Using Hidden Fields to Pass Data

• Hidden fields are part of HTML forms
• Not displayed but value can be accessed in
  receiving script like any other variable.
• Can still be viewed by users who view source.

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A Full Script Example

• Consider an example script sets a hidden field
• Implements the Order Info form
• on submit sends data to http//webwizard.aw.com/p
  hppgm/C7/order2.php

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PHP Script

• 1. lthtmlgtltheadgtlttitlegtOrder Productlt/titlegtlt/headgt
  ltbodygt
• 2. ltform action"http//webwizard.aw.com/phppgm/C
  7/order2.php"
• method"post"gt
• 3. ltfont color"blue" size"5"gt Happy Harry's
  Hardware Product
• Order Formlt/fontgt
• 4. ltbrgtltfont color"red" size"4"gt
• 5. We have hammers, handsaws, and wrenches on
  special today!
• 6. lt/fontgt
• 7. ltinput type"hidden" name"sample_hidden"
  value"Welcome!"gt
• 8. ltbrgtEnter Item ltinput text type"text"
  size"15 maxlength"20" name"product"gt
• 9. Enter Quantity ltinput text type"text"
  size"15 maxlength"20" name"quantity"gtltbrgt
• 10. ltbrgtltinput type"submit" value"Click To
  Submit"gt
• 11. ltinput type "reset" value"Reset"gt
• 12. lt/formgtlt/bodygtlt/htmlgt

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The Output ...

• The previous code can be executed at
  http//webwizard.aw.com/phppgm/C7/order.html

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Receiving Hidden Fields in Web Sessions

• Your scripts can receive data from hidden fields
  like any other data.
• Suppose the following is stored at
  http//webwizard.aw.com/phppgm/C7/order2.php

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Receiving PHP Script

• 1. lthtmlgtltheadgtlttitlegt Order Product 2 lt/titlegt
  lt/headgt
• 2. ltbodygt
• 3. ltform action"http//webwizard.aw.com/phppgm/C
  7/order3.php method"post"gt
• 4. lt?php
• 5. print "ltfont size5 colorbluegt"
• 6. print "Hidden valuesample_hidden
  ltbrgtlt/fontgt"
• 7. print "You selected productproduct and
  quantityquantity"
• 8. print "ltbrgtltbrgtltinput type\"hidden\"
  name\"product\ value\"product\"gt "
• 9. print "ltinput type\"hidden\"
  name\"quantity\ value\"quantity\"gt"
• 10. print "ltinput type\"hidden\"
  name\"sample_hidden\"value\"sample_hidden\"gt"
• 11. print 'Please enter your name'
• 12. print 'ltinput type"text" size"15"
  maxlength"20 name"name"gt'
• 13. print ' and billing code (5 digits)'
• 14. print 'ltinput type"text" size"5"
  maxlength"5"
• name"code"gt'
• 15. print 'ltbrgt ltinput typesubmit value"Process
  Order"gt'
• 16. print 'ltinput typeresetgt'
• 17. ?gtlt/formgtlt/bodygtlt/htmlgt

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Receiving PHP Script With REGISTER_GLOBALS Off

• 1. lthtmlgtltheadgtlttitlegt Order Product 2 lt/titlegt
  lt/headgt
• 2. ltbodygt
• 3. ltform action"http//webwizard.aw.com/phppgm/C
  7/order3.php method"post"gt
• 4. lt?php sample_hidden _POSTsample_hidden
  
• 5. product _POSTproduct quantity
  _POSTquantity
• 5. print "ltfont size5 colorbluegt"
• 6. print "Hidden valuesample_hidden
  ltbrgtlt/fontgt"
• 7. print "You selected productproduct and
  quantityquantity"
• 8. print "ltbrgtltbrgtltinput type\"hidden\"
  name\"product\ value\"product\"gt "
• 9. print "ltinput type\"hidden\"
  name\"quantity\ value\"quantity\"gt"
• 10. print "ltinput type\"hidden\"
  name\"sample_hidden\"value\"sample_hidden\"gt"
• 11. print 'Please enter your name'
• 12. print 'ltinput type"text" size"15"
  maxlength"20 name"name"gt'
• 13. print ' and billing code (5 digits)'
• 14. print 'ltinput type"text" size"5"
  maxlength"5"
• name"code"gt'
• 15. print 'ltbrgt ltinput typesubmit value"Process
  Order"gt'
• 16. print 'ltinput typeresetgt'
• 17. ?gtlt/formgtlt/bodygtlt/htmlgt

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Sending email from PHP scripts

• Sometimes it is useful to send email from a PHP
  script
• PHP uses mail() that by default sends e-mail via
  the Simple Mail Transfer Protocol (SMTP).
• mail(to_address, subject, message,
  extra_headers)

Specify the Text of the email
Specify the destination email address.
Specify the subject line of the e-mail.
Specify additional email headers.
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Consider the following example

• 1. dest'orders_at_hardwareville.com'
• 2. subject 'New Hardware Order'
• 3. message 'Enclosed is a new order for 12
  hammers.\n Thanks.'
• 4. extra 'From harry_at_hardwareville.com'
• 5. mail( dest, subject, message, extra )

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Consider the following full example

• Implements save and notify
• Called from order2.php and saved at http//
• webwizard.aw.com/phppgm/C7/order3.php
• Can access variables product, quantity, and
  sample_hidden sent as hidden fields from the
  Billing Info form.

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The following PHP Script

• 1. lthtmlgtltheadgtlttitlegtOrder Product 3lt/titlegt
  lt/headgtltbodygt
• 2. lt?php
• 3. email'orders_at_hardwareville.com'
• 4. body "New Order Productproduct
  Numberquantity Custname Codecode"
• 5. print 'ltfont size4gt'
• 6. print "ltbrgtSending e-mail to order handling
  department at email ... lt/fontgt"
• 7. print "ltbrgtThe e-mail body is ltigt body.
  lt/igt"
• 8. from 'harry_at_hardwareville.com'
• 9. subject "New order from name"
• 10. mail(email, subject, body, "From from")
• 11. print 'ltbrgtltfont color"blue"gt E-mail sent.
  Thanks for ordering. lt/fontgt'
• 12. print "ltbrgtBy the way, sample
  hiddensample_hidden"
• 13. ?gtlt/bodygtlt/htmlgt

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The following PHP Script with REGISTER_GLOBALS
Off

• 1. lthtmlgtltheadgtlttitlegtOrder Product 3lt/titlegt
  lt/headgtltbodygt
• 2. lt?php
• 3. sample_hidden _POSTsample_hidden
  quantity_POSTquantity
• 4. product _POSTproduct
  name_POSTname
• 3. email'orders_at_hardwareville.com'
• 4. body "New Order Productproduct
  Numberquantity Custname Codecode"
• 5. print 'ltfont size4gt'
• 6. print "ltbrgtSending e-mail to order handling
  department at email ... lt/fontgt"
• 7. print "ltbrgtThe e-mail body is ltigt body.
  lt/igt"
• 8. from 'harry_at_hardwareville.com'
• 9. subject "New order from name"
• 10. mail(email, subject, body, "From from")
• 11. print 'ltbrgtltfont color"blue"gt E-mail sent.
  Thanks for ordering. lt/fontgt'
• 12. print "ltbrgtBy the way, sample
  hiddensample_hidden"
• 13. ?gtlt/bodygtlt/htmlgt

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Would have the following output
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Would have the following output
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Using Browser Cookies

• Cookies are small pieces of data that a Web
  application can save when a user visits the Web
  page.
• Stored on the visitors hard drive
• a Web page script can read the previously stored
  browser cookie data

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Understanding Cookie Limitations

• Users can easily disable the cookies feature.
• People move around.
• Users may delete cookies.
• PHP sets limit on cookies

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The disable cookie screen in Netscape
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Setting and Reading Cookies

• Cookies can be set in memory or on hard disk
• Set on memory are deleted when browser closes
• Those saved in HD retained until some defined
  expiration date
• Can use the setcookie() script
• setcookie('Customer_name', 'Denise')

Directs browser to create a cookie
Specify the cookies name
Specify the cookies value
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Setting A Cookie on a Hard Drive

• You need to use the time() function when want to
  set a cookie on a hard drive.

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A full example of setting a cookie.

• Suppose a front-end web page asks for some survey
  information
• ltinput type"text" size"15" maxlength"20"
  name"custname"gt
• ltinput type"radio" name"prefers" value"power
  tools"
• checked gt Power Tools?
• ltinput type"radio" name"prefers"
• value"hand tools"gt Hand Tools?
• ltinput type"radio" name"prefers
• value"air fresheners"gt Air Fresheners?

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The following script runs when submitted

• 1. lt?php
• 2. expire time() (60 60 24 30)
• 3. setcookie("name", custname, expire)
• 4. setcookie("preference", prefers, expire)
• 5. ?gt
• 6. lthtmlgt
• 7. ltheadgtlttitlegtHappy Harry's Hardware Catalog
  lt/titlegtlt/headgt
• 8. ltbodygtltfont size4 color"blue"gt
• 9. lt?php
• 10. print "Thanks custname!
• 11. print Lets now look at prefers... "
• 12.?gt lt/fontgtlt/bodygtlt/htmlgt

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The following script runs when submitted (With
REGISTER_GLOBALS Off).

• 1. lt?php prefers _POSTprefers
  expire_POSTexpire custname_POSTcustna
  me
• 2. expire time() (60 60 24 30)
• 3. setcookie("name", custname, expire)
• 4. setcookie("preference", prefers, expire)
• 5. ?gt
• 6. lthtmlgt
• 7. ltheadgtlttitlegtHappy Harry's Hardware Catalog
  lt/titlegtlt/headgt
• 8. ltbodygtltfont size4 color"blue"gt
• 9. lt?php
• 10. print "Thanks custname!
• 11. print Lets now look at prefers... "
• 12.?gt lt/fontgtlt/bodygtlt/htmlgt

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Would output
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Reading Cookies

• You can read a cookie by using a variable name
  with the same name as a cookie
• print cust_name

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Reading Cookies with REGISTER_GLOBALS Of

• To read a cookie value use the _COOKIE
  associative array to get the cookie function
• cust_name _COOKIEcust_name

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Example Script that read a cookie

• 1. lthtmlgt
• 2. ltheadgtlttitlegtHappy Harry's Hardware
  Cataloglt/titlegt
• 3. lt/headgtltbodygt
• 4. lt?php
• 5. print 'ltfont color"blue" size4gt'
• 6. if (isset(name))
• 7. print "Welcome back to our humble hardware
  site, name."
• 8. else
• 9. print 'ltfont color"red"gt'
• 10. print 'Welcome to our humble hardware
  site.lt/fontgt'
• 11.
• 12. if (preference 'hand tools')
• 13. print 'ltbrgt We have hammers on sale for 5
  dollars!'
• 14. elseif (preference 'power tools')
• 15. print 'ltbrgt We have power drills on sale
  for 25 dollars!'
• 16. elseif ( preference 'air
  fresheners')
• 17. print 'ltbrgt We now carry extra-strength
  air fresheners!'
• 18. else
• 19. print 'ltbrgt ltfont color"red"gt'

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Example Script that read a cookie

• 1. lthtmlgt
• 2. ltheadgtlttitlegtHappy Harry's Hardware
  Cataloglt/titlegt
• 3. lt/headgtltbodygt
• 4. lt?php name _COOKIEname preference
  _COOKIEpreference
• 5. print 'ltfont color"blue" size4gt'
• 6. if (isset(name))
• 7. print "Welcome back to our humble hardware
  site, name."
• 8. else
• 9. print 'ltfont color"red"gt'
• 10. print 'Welcome to our humble hardware
  site.lt/fontgt'
• 11.
• 12. if (preference 'hand tools')
• 13. print 'ltbrgt We have hammers on sale for 5
  dollars!'
• 14. elseif (preference 'power tools')
• 15. print 'ltbrgt We have power drills on sale
  for 25 dollars!'
• 16. elseif ( preference 'air
  fresheners')
• 17. print 'ltbrgt We now carry extra-strength
  air fresheners!'
• 18. else
• 19. print 'ltbrgt ltfont color"red"gt'

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PHP Sessions

• PHP supports two functions that enable you to
  retain data between forms
• session_start() - either starts a new session or
  resumes one if a session exists
• Run at the start of every script
• By default creates a unique session ID stored as
  a cookie
• session_register() - registers one or more
  variables as session variables
• name 'Matthew'
• preference 'Soccer Equipment'
• session_register('name', 'preference')

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Example PHP Code

• 1. lt?php session_start() ?gt
• 2. lthtmlgtltheadgtlttitlegtOrder Productlt/titlegt
• 3. lt/headgtltbodygt
• 4. ltform action
• "http//webwizard.aw.com/phppgm/C7/ses
  sions2order.php"
• method"post"gt
• 5. ltfont colorblue size5gt Hardware Product
  Order Form lt/fontgt
• 6. ltbrgt We have hammers, handsaws, and wrenches.
• 7. ltbrgtEnter Item ltinput text type"text"
  size"15" maxlength"20" name"product"gt
• 8. Enter Quantity ltinput text type"text"
  size"15" maxlength"20" name"quantity"gtltbrgt
• 9. lt?php
• 10. sample_hidden'Welcome Again!'
• 11. session_register('sample_hidden')
• 12. ?gt
• 13. ltbrgtltinput type"submit" value"Click To
  Submit"gt
• 14. ltinput type "reset" value "Reset" gt
• 15. lt/bodygtlt/htmlgt

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Example output
This script can be executed at
http//webwizard.aw.com/phppgm/C7/ordersession.
php
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Use the following script to read the session data

• 1. lt?php session_start() ?gt
• 2. lthtmlgtltheadgtlttitlegt Order Product 2 lt/titlegt
  lt/headgt
• 3. ltbodygt
• 4. ltform action"http//webwizard.aw.com/phppgm/C
  7/sessions3order.php " method"post"gt
• 5. lt?php
• 6. print "ltfont colorblue size4gt Sample
  hidden sample_hiddenlt/fontgt"
• 7. print "ltbrgtYou selected productproduct
  and quantityquantity"
• 8. session_register('product', 'quantity')
• 9. print 'ltbrgtPlease enter your name'
• 10. print 'ltinput text type"text" size"15"
  maxlength"20" name"name"gt'
• 11. print ' and Billing Code (5 digits)'
• 12. print 'ltinput text type"text" size"5"
  maxlength"5" name"code"gt'
• 13. print 'ltbrgt ltinput typesubmit
  value"Process Order"gt'
• 14. print 'ltinput typeresetgt'
• 15. print 'lt/formgtlt/bodygtlt/htmlgt'
• 16. ?gt

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Example output
This script can be executed at
http//webwizard.aw.com/phppgm/C7/ordersession.
php
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Some session extras

• session_is_registered() - can be used to
  determine if a variable comes from a session
• if (session_is_registered('name'))
• print "got namename from session"
• else
• print "namename not set from session"

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Session Extras - _SESSION

• Use _SESSION Associative array when
  REGISTER_GLOBALS are off in php.ini
• Do not need to use session_register()
• session_start()
• _SESSION'sample_hidden' 'Welcome!'

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Summary

• Hidden fields are HTML form fields you can use to
  set a variable name and variable value without
  displaying them on a form.
• Cookies provide a way for Web server applications
  to store small pieces of data on the users hard
  disk.
• PHP session functions provide a convenient way to
  retain data between PHP scripts.
• Use session_start() and session_register()
  functions to start sessions and define session
  variables, respectively