Includes, PRG, Mail

Dr. Andrew Besmer

Scenario

Scenario

  • Todo App

We will create a todo web app that will link todo items with peoples email addresses. The todo app will be able to support adding/deleting todo items as well as sending a reminder email, reminding a person of the todo item. We will do all this using as much reusable code as possible.

Includes

Reusable Code

  • How many times have you typed the basic html structure?
<!DOCTYPE html>
<html>
    <head>
        <title></title>
    </head>
    <body>
    </body>
</html>

Reusable Code

  • So far all code has been in same file
  • Code is unreusable from
    • Page to page
    • App to app

Includes/Requires

  • Includes & requires to the rescue
    • The include() asks that file be inserted/parsed
      • Absence of the file allows script to continue execute
    • The require() demands that a file be inserted/parsed
      • Absence of a file causes script to have fatal error and terminate

Includes/Requires

  • Lets make a header/footer for our todo app
    • Decide between require/include
<?php
require("header.php");

//Your page stuff here

require("footer.php");

Includes/Requires

  • Includes and requires are useful for reusing code
  • Lets make reusable code for reading, writing, and deleting from a file1
    • readLines($filename) - Read all the lines from the file
    • appendLine($filename, $line) - Append a specific line from the file
    • deleteLine($filename, $lineNumber) - Delete a specific line from the file

_once

  • Both include() and require() have similar functions postfixed with _once
    • include_once()
    • require_once()
  • Ensures file was included at most 1 time
    • Useful for helper files containing functions
    • Recall functions can be declared only once

Form Inputs

Select

  • HTML select tag is used to provide a list of items from which you can select just one item
    • Visually a drop down list
    • name attribute on option element used as the key
    • value attribute on option used to indicate choice
    • Longer text inside option tags is only shown to user
<select name="state">
    <option value="NC">North Carolina</option>
    <option value="SC">South Carolina</option>
</select>

Select

  • Lets implement the todo app with our generic reader and writer
    • Insert todo item and email (select) it belongs to
    • Summary of items

Hidden

  • hidden inputs can be used to provide form information that the user does not get to see
    • Useful for security (another class)
    • Also useful for forms with no visible input
<input type="hidden" name="sku" value="456789"></input>

Hidden

  • Lets implement delete functionality using a form
    • A hidden input for todo item number
    • Button for delete command
  • Why use a form instead of a button?
    • GET vs POST intention
    • Should really use DELETE but GET/POST are the only universally supported form methods
    • AJAX can support DELETE/PUT in many browsers

PRG

PRG Pattern

PRG
Post/Redirect/Get Pattern - solves a common problem with browsers and HTTP POST requests.

PRG Problem 2

PRG Pattern

  • By redirecting can avoid double submission

PRG Solution 3

PRG

  • Does our todo app have a double POST problem?
  • Lets try inserting and deleteing to find out

PRG

  • How can we fix with PHP

 

  • header() function
  • Lets fix it it

Mail

Mail

  • Sending mail to users is a common task performed by nearly every web app
  • Examples
    • User registration
    • Forgot password
    • New bill generated
    • Todo reminder!

Mail

  • The mail protocol is similar to the http protocol
  • Can use the mail() function in PHP to send mail mail function
mail($to, $subject, $message, $headers);

Mail

  • $to must follow standard
    • besmera@winthrop.edu
    • besmera@winthrop.edu, dannellys@winthrop.edu
    • Andrew Besmer <besmera@winthrop.edu>
  • $subject must contain no \r\n

Mail

  • $message can contain multiple lines and is used for the message body
  • $headers while not required can contain additional headers
    • From: is one header you almost certainly want to set
mail("besmera@winthrop.edu", 
"New Account", 
"Welcome to the site!\r\n\r\nVisit us soon...", 
"From: no-reply@winthrop.edu");

Mail

  • Lets implement a remind feature
  • Address refresh problem

  1. OOP or passing the file name would be more suitable than our example but we are not ready for that.↩︎

  2. Source: http://upload.wikimedia.org/wikipedia/commons/f/f3/PostRedirectGet_DoubleSubmitProblem.png↩︎

  3. Source: http://upload.wikimedia.org/wikipedia/commons/3/3c/PostRedirectGet_DoubleSubmitSolution.png↩︎