Chapter 5

1
Chapter 5 Handling HTML Controls in Web
Pagesspring into PHP 5by Steven Holzner

• Slides were developed by Jack DavisCollege of
  Information Scienceand TechnologyRadford
  University

2
HTML Form Fields

• in this chapter, we look at how to read data from
  form fields on html documents
• buttons
• checkboxes
• hidden fields
• image maps
• lists
• passwords
• radio buttons
• reset button
• select (Menus)
• submit button
• text areas
• text fields

3
Handling Client Data

• Reviewan html document may contain a form. A
  form tag includes an action attribute, that
  specifies the server side script to send the form
  data toltform action"https//php.radford.edu/
  jcdavis/phpscript.php"
  method "post" gtltinput type"text"
  name"txt1" size"20"
  maxlength "30" /gtltinput type"submit"
  value"submit data" /gtlt/formgtif method is
  post, the data will be accessed via the _POST
  array, if method is get then the data will be in
  _GET array. the _REQUEST array holds data from
  both post and get. These are superglobal arrays.

4
html Form

• form tagltform name"fm1"
  action"https//php.radford.ed " method
  "post" gtform field examples ---ltpgtEnter
  first nameltinput type"text" size"20"
  maxlength"30" name"fn"
  /gtlt/pgtltpgtltinput type"checkbox" name"chk1"
  value"book1" checked"checked"
  /gtltinput type"radio" name"age"
  value"under20" /gtUnder 20ltbr /gtltinput
  type"radio" name"age" value"21-40"
  /gt21 - 40lt/pgt

5
form Fields (cont.)

• ltinput type"submit" value"Submit Data"
  /gtltinput type"reset" value"Clear Form"
  /gtMenu's and text area's can also be used
  collect data on an html form.Processing
  data.in php codefrom a text boxtxt
  _POST"fn"from a check box, if a check box
  has been checked it's value will be included in
  the query stringchk1 _POST"chk1"chk1's
  value will be "book1"

6
Getting data from RB's

• ltinput type"radio" name"age"
  value"lt20" /gtUnder 20ltbr /gtltinput type"radio"
  name"age" value"20-40" /gt20-40ltbr
  /gtltinput type"radio" name"age"
  value"over 40" /gtltbr /gt--------------------r
  eceiving codelt?php age _POST"age"
• What will age value be if the first radio button
  is clicked?

7
Hidden Fields

• let's you store hidden data in html
  documentssay you had a multi-form application,
  so the user fills out one form and clicks on
  submit.the server application collects the data
  and then wants to have the user enter more info.
  on a new form. hidden fields can be used to
  insert this data into the second form, so it will
  return when the submit button on the second form
  is clicked.ltinput type"hidden" name"hide1"
  value"under 20" /gtwhen the second
  form is submitted, the data can be retrieved as
  you would for a text field

8
Password Form Fields

• In PHP these are nearly the same as text boxes.
  However, the characters the user enters into the
  text field are not echoed to the screen. Rather
  an asterisk is echoed so the password can not be
  read by casual viewers of the screen. ltinput
  type"password" name"pass1" /gtit is read in
  php just like a text field.lt? password
  _POST"pass1"Note -- the password is not
  necessarily encrypted in the query string
  

9
Image Maps

• PHP supports html image maps, which are clickable
  images full of hot spots, although you work with
  them differently in php.to create an image map
  you useltinput type"image" name"imap"
  src"imap.jpg" /gtwhen the user clicks the
  map, the mouse location is sent to the
  server.xloc _POST"imap_x"when you know
  where the map was clicked you can use that info.
  to take different actions

10
Uploading Files

• HTML forms can be used to upload files. Assume
  you wish to upload a file named message.txt and
  make this text available to the php server
  scriptltform enctype"multipart/form-data"
  action"phpfile.php" method"post"
  /gtUpload this file ltinput
  name"userfile" type"file"
  /gtltinput type"submit" value"Send File"
  /gtlt/formgt

11
Reading Uploaded Files

• There's another superglobal array _FILES, it
  gives you access to the uploaded
  file_FILES'userfile''name'
  original name of the file from user_FILES'user
  file''type' MIME type of the
  file for example -- "text/plain" or
  "image/gif")_FILES'userfile''size'
  size of the uploaded file in
  bytes_FILES'userfile''tmp_name'
  temporary filename of the file in
  which the uploaded file was stored on
  the serverwhen a file is uploaded, it's
  stored as a temporary file on the server, and you
  accessusing - _FILES'userfile''tmp_name'

12
Reading Uploaded Files (cont)

• We'll see more about reading and writing files in
  chapter 6, but briefly here's the method used to
  open and read an uploaded filelt?php handle
  fopen(_FILES'userfile''tmp_name',"
  r") while(!feof(handle)) text
  fgets(handle) echo text, "ltbr /gt"
  fclose (handle)?gt

13
Form Buttons, Method 1

• You may want have multiple buttons on an html
  form, the question how can you tell which
  button(s) was (were) clicked by the client
• First method, when a button is clicked on a form
  put a description in a hidden field, then read
  that field in the php server script. A
  javascript will have to be included in the html
  formltform action"phpbuttons.php"
  method"post" name "form1"gtltinput
  type"hidden" name"button" /gtltinput
  type"button" value"b1" onclick
  "button1()" /gtlt/formgt---------------
  javascripts next slide

14
Buttons Method 1

• the following javascript would have to be
  included in the html form documentltscript
  language"JavaScript"gtlt!-- function
  button1() document.form1.Button.value
  "b1" form1.submit() function
  button2() document.form1.Button.value"b
  2" form1.submit() lt!-- one
  function per buttonlt/scriptgt--the receiving
  script then reads the hidden field to determine
  which button was clicked

15
Buttons Method 2

• The second method is to build multiple forms on
  one html document. One form for each button.
  Each button could then be built using a submit
  button (there can only be one submit button on a
  form). There would be a hidden field in each
  form that contains the name of the submit button
  for that formOne php server script can be
  specified in the action attribute of each form.
  The identity of the button can be read in the php
  server script by reading the hidden field. Each
  hidden field can be preset with the name of the
  submit button in that form.The problem with
  this approach is that if there is extra data to
  be included on the form, it has to be on all
  three forms. So, this method is rarely used.

16
Buttons Method 3

• You can pass data back to the server script by
  using the value attribute of the submit
  button.You still must use three different forms,
  each with a submit button with the same name. We
  still have three forms, but the hidden field on
  each form is not needed.Each submit button
  would have a different value, the string
  displayed on the face of the button. In the
  php server script we would access the value as
  inlt?php if (isset(_POST"Button"))
  echo _REQUEST"Button", "ltbr /gt"?gtwhy
  could you use both the _POST and the _REQUEST
  super global arrays?

17
Class Exercise

• Build a three part form- the first document is
  a form that has a text field that calls one php
  server script. This script puts the contents
  of the text field into another form and asks the
  user to indicate how many times they want to
  concatenate that entry together. It calls a
  second php script.The second server script
  performs the concatenation and outputs back to
  the client the original string entered and the
  concatenated string. This script should contain
  a function that is called multiple times to do
  the concatenation, it should utilize a static
  variable.