Simple PHP ToDo App and notes put together to help teach development to Waukee school's APEX program
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.idea
ajaxwithdelete
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loginpage
simple
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README.md
db_config.php
index.php

README.md

Basic Development Fundamentals

  • Variables
    • Like basic algebra
     x = 4
     x = x + 2
     print x
  • Arrays
    • A list of items
    • Numbered index
    array_cars('ford', 'honda');
    print array_cars[1];
  • Named indexes
    array('first' => 'ford', 'second' => 'honda');
    print array['first'];
  • Classes/Objects
    • The ultimate variable type
    • The basic structure is called a class, and implementation of that class is an object
    • Can contain its own variables called "properties"
    • Can contain functions called "methods"
    object_car1->make = 'ford'
    object_car1->color = 'grey'
    object_car1->mileage = '35000'
    object_car1->state = 'dirty'
  • Lets say we have a method called "wash" that changes the car's state to 'clean'
    object_car1->wash
    print object_car1
  • Conditional
    • Logical operations
    x > y
    x >= y
    x < y
    x <= y
    x != y
    x > y && a < b
    x < y || a > b
    if (x > 2) {
        print("Yay, x is greater than 2");
       } else {
        print ('Boo, x is 2 or less');
       }
  • Loops
    • Repeat things for a number of times, or until some condition is met
    while ( x < 10) {
        print ('X = ' . x);
        x = x + 1; // or x++;
    }
    do {
        print ('X = ' . x);
        x = x + 1; // or x++;
    } while (x < 10)
    for (x = 0; x < 10; x++){
        print ('X = ' . x);
     }
  • Functions
    • A sort of black box that ask to do something and it generally responds with an answer
    function add ( $x, $y ) {
        return $x + $y;
    }      
    $x = add( 3, 4);
  • Scope
    • You can have a variable within a function that shares a name with a variable outside of that function and there are zero issues with that.
    • Global scope
    • Function scope

PHP Specifics

  • Variables must start with a $
  • Variable names are case sensitive: $x and $X are two different variables
  • First character of a variable name (after the $) can't be a number.
  • End of line signified by a ;

ToDo

Simple PHP ToDo App

  • Think through problem
    • Minimum viable product features
      • Create
      • Update
      • Delete
    • Nice to have features
      • Edit a ToDo's text
      • Due dates
      • Reminders
      • Recurrence
      • Ajax
  • Pseudo code
    • Think like a user
      • How will you interact with the list?
      • What edge cases do you need to handle?
    • Write out workflow as comments
  • Front End
    • Form elements
  • Back End Code
    • Simple single page PHP form handling
    • Processing page handling
      • Separate presentation layer from processing
    • AJAX handling
  • Back End Database
    • MySQL
      • Fields
        • id
        • todo
        • done
    CREATE TABLE IF NOT EXISTS `tb_todos` (
      `id` bigint(20) NOT NULL AUTO_INCREMENT,
      `todo` text NOT NULL,
      `done` tinyint(1) NOT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

SQL Basics

If you want a good place to learn the basics of SQL try this SQLZoo playground. It lets you run various queries against their sample tables. http://sqlzoo.net/

Database and PDO

PDO (PHP Data Objects) is currently the best way to interact with a database within PHP. It provides some simple classes that make connecting to and getting data into and out of a database easier, and also simplifies interacting with different types of databases (MySQL, MS SQL, Oracle, PostgreSQL).

  • db-config.php
    <?php
    //keep this database info in a single file so that you only have to change it once to update your whole project
    $db_info['server'] = 'localhost';
    $db_info['name'] = '';
    $db_info['user'] = '';
    $db_info['pass'] = '';
  • Setting up a connection to a database and setting the error mode to aid in debugging
//pull in our db_config file
require_once('db_config.php'); //or whatever the path to your file is, this assumes it's a file in our current directory
//create a connection to our database using a "connection string" which tells PDO the type of database and other info it needs to communicate with it
$db = new PDO('mysql:host=' . $db_info['server'] . ';dbname=' . $db_info['name'] . '', $db_info['user'], $db_info['pass']);
//sets the attribute "Error Mode" to "Exceptions" so that our code is easier to debug
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
  • Selecting some data from a table
    • Select if only expecting a single result
//prepare our SQL statement with parameters for the variables we need to pass in
$stmt = $db->prepare( "SELECT field1, field2 FROM MYTABLE WHERE field3 = :field3 AND field4 = :field4" );
//tells our $stmt object that this parameter "field3" = the value of this PHP variable "$field3" and it should treat it like a string
$stmt->bindParam(':field3', $field3, PDO::PARAM_STR);
//same as above but this parameter should be treated as an integer
$stmt->bindParam(':field4', $field4, PDO::PARAM_INT);
//run our fully prepared query
$stmt->execute();
//assign the results of our query to a variable that we can work with in our code
//PDO::FETCH_OBJ returns a single result as an object as opposed to PDO::FETCH_ASSOC which would return the result as an array
$result = $stmt->fetch(PDO::FETCH_OBJ);  

//with PDO::FETCH_OBJ
print( 'Field 1: ' . $result->field1 . '<br />');
print( 'Field 2: ' . $result->field2 . '<br />');
print('<br />');

//with PDO::FETCH_ASSOC
print( 'Field 1: ' . $result['field1'] . '<br />');
print( 'Field 2: ' . $result['field2'] . '<br />');
print('<br />');
  • Select if expecting more than one result
$stmt = $db->prepare( "SELECT field1, field2 FROM MYTABLE WHERE field3 = :field3" );
$stmt->bindParam(':field3', $field3, PDO::PARAM_STR);
$stmt->execute();
//return a collection of result objects or result arrays if using PDO::FETCH_ASSOC
$results = $stmt->fetchAll(PDO::FETCH_OBJ);  

//step over our results with a foreach loop
foreach ( $results as $result ) {
  print( 'Field 1: ' . $result->field1 . '<br />');
  print( 'Field 2: ' . $result->field2 . '<br />');
  print('<br />');
}
  • Insert data into a table
$stmt = $db->prepare( "INSERT INTO MYTABLE(field1, field2) VALUES(:field1, :field2)" );
$stmt->bindParam(':field1', $field1, PDO::PARAM_STR);
$stmt->bindParam(':field2', $field2, PDO::PARAM_INT);
$stmt->execute();
  • Edit data in a table
$stmt = $db->prepare( "UPDATE MYTABLE SET field1 = :new_field1 WHERE field2 = :field2" );
$stmt->bindParam(':new_field1', $field1, PDO::PARAM_STR);
$stmt->bindParam(':field2', $field2, PDO::PARAM_INT);
$stmt->execute();
  • Delete data into from table
$stmt = $db->prepare( "DELETE FROM MYTABLE WHERE field1 = :field1" );
$stmt->bindParam(':field1', $field1, PDO::PARAM_INT);
$stmt->execute();

Table for our Login App

CREATE TABLE IF NOT EXISTS `tb_users` (
 `user_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
 `user_name` varchar(255) NOT NULL,
 `password` varchar(255) NOT NULL,
 `access_level` int(11) NOT NULL,
 PRIMARY KEY (`user_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;