Php form input, Exams of Advanced Computer Programming

INPUT Control Types

• text : single input line
• password : single input line, with input characters obfuscated
• checkbox : creates a check list
• radio : creates a radio button list (checkbox, where inputs are mutually exclusive – only one input at a time)
• button : push button
• hidden : a hidden control. No input field is visible, but value is submitted as part of the form

INPUT control types

• Special buttons
  • submit : the submit button. Causes input to be sent to the server for processing
  • reset : the reset button. Causes all input fields to be reset to their initial values
• File upload
  • file : creates a file upload control

Receiving form input in PHP

• Upon receiving a form submission, PHP automatically creates and populates two arrays with the form input data - Either: _POST[] or _GET[], depending on the FORM method type (post or get) - Also: HTTP_POST_VARS[] or HTTP_GET_VARS[] - Also: $name - Requires register_globals option, and is generally a bad idea due to cross-site attacks - Additionally, _REQUEST[] is also created
• The array indicies are the names of the form variables (INPUT name=…)
• The array value is the user entry data

Validating Data

• All web applications must validate user

input data

• Ensure the data is syntactically correct, and meets input constraints
• Ideally want one PHP page to create

form, validate input, and handle correct

input

• This is a little tricky

How to determine if first time

• Can check if the $_POST[] array is empty
  • Will be empty first time through
  • if (empty($_POST)) { create initial form }
  • if (!empty($_POST)) { validate input }

All-in-one structure

• Functions for input validation
• Function(s) that creates form
  • Default values set from contents of _POST[]
• HTML preamble
• Create initial form
• Validate input
• Recreate form
• Code to handle valid input
• HTML end