I’ll admit it now that I was a little lazy when developing some of the classes. I went back and modified them so that they would implement exception handling, only I went one step further and used custom exception handling so that I could log any errors that may occur.

Within this posting, im going to create a class that will have errors, and I’ll also create a custom exception class that will catch any of these errors and log them to a file

You can download the complete source here. This class will be a very basic SQL class that will:

• Connect to a database
• Disconnect from a database
• Select from a database

The directory setup after this tutorial should look as follows:

Directory Setup

• index.php
• /lib/
  • SQL.class.php
  • SQL.exception.class.php
• /sql/
  • world.sql
• SQLException.log

Make sure you have the world database installed within your database. You can download it here or find it in the download of the completed source.

The SQL class

Before I jump into the mix, this is written for people whom already have a basic grasp on any OOP language, as well as some of the basics of exception handling.

SQL.class.php

<?php

include('SQL.exception.class.php');

class SQL {

	private $username;
	private $password;
	private $database;
	private $connection;

	/**
	*
	*
	*/
	public function  __construct($u,$p,$d) {
		$this->username = $u;
		$this->password = $p;
		$this->database = $d;
		$this->connection = false;
	}

	public function connect() {
		if(!$this->connection) {
			// use @ to surpress the error
			if(!@mysql_connect('localhost',$this->username,$this->password)) {
				throw new SQLException('Can\'t connect to the database, either the username or password are wrong');
			}

			// use @ to surpress the error
			if (!@mysql_select_db($this->database)) {
				throw new SQLException('The database '.$this->database.' does not exist.');
			}

			$this->connection = true;
		}
	}

	public function disconnect() {
		if($this->connection) {
			mysql_close();
			$this->connection = false;
		}
	}

	public function getCity($city) {
		$cities = array();

		$query = 'SELECT * FROM City WHERE NAME ='."'$city'";
		$results = @mysql_query($query);
		if ($results) {
			while($row = mysql_fetch_array($results)) {
				$cities[] = $row;
			}

			if (sizeof($cities) > 0) {
				return $cities;
			}
			else {
				throw new SQLException('The following city: '.$city.' was not found',$query);
			}
		}
		else {
			throw new SQLException('Error with query when trying to get a city: ',$query);
		}
	}
}

?>

Theres the SQL class. Theres a few things in here that I should make note of. First, I’ve included the SQLException custom class, we have yet to create that, so hang on for now! Secondly the way that a try catch block works, is that it needs to try to do something and if that something does not work, it will catch that exception to better handle it. In order to catch an exception one must be thrown. We’re throwing the exceptions anytime we feel an error might need to be reported.

Next up the custom exception class

Create a new file within your lib folder called “SQL.exception.class.php”

SQL.exception.class.php

<?php
class SQLException extends Exception {

	// path to the log file
	private $log_file;

	public function __construct($message=NULL, $query = NULL) {

		// NOTE:: THIS MAY NEED TO CHANGE
		$this->log_file =  $_SERVER['DOCUMENT_ROOT'].'/'.$_SERVER['REQUEST_URI'].'/SQLException.log';

		$code = mysql_errno();
		$sql_error = mysql_error();

		// open the log file for appending
		if ($fp = fopen($this->log_file,'a')) {

			// construct the log message
			$log_msg = date("[Y-m-d H:i:s]") .
				" Code: $code " .
				" || Message: $message".
				" || SQL error: $sql_error \n".
				"Query: $query\n-------\n";

			fwrite($fp, $log_msg);

			fclose($fp);
		}

		// call parent constructor
		parent::__construct($message, $code);
	}

}
?>

All the magic here happens when we extend PHP’s Exception class. Moving down to the class constructor, I’ve set up two parameters. $message takes the message that will be passed into the parent constructor. This message will be shown to the user to better explain whats going. The second parameter $query is meant for the log file. This is passed in so that we as the developers can view the query that may have been botched. Moving into the constructor now, it’s important to provide a path to the logfile, so the first line of code we see does just that. Next the two variables $code and $sql_error grab a little more information for the log file. The las bit of code opens the log file, appends a new entry, saves and closes it. To finish the class off, run the parents constructor.

Finally the index or testing file.

This is the index file that will be within our root directory. It contains sets of variables to help generate exceptions. This file is also where we “try” to complete a statement and if anything goes wrong we “catch” that exception, kill the script and explain why things didn’t work out.

index.php

<?php
include_once('lib/SQL.class.php');

// ==================== EXCEPTION ERROR ====================
// switch these two database variables to see a exception error occur
$database = 'world';
//$database = 'wrongDB';			// <--- this will result in an exception error when uncommented.

// ==================== EXCEPTION ERROR ====================
// switch these two username variables to see a exception error occur
$username = 'root';
//$username = 'wrongUserName';		// <--- this will result in an exception error when uncommented.

// ==================== EXCEPTION ERROR ====================
// switch these two username variables to see a exception error occur
$password = 'root';
//$password = 'wrongPassword';		// <--- this will result in an exception error when uncommented.

// ==================== EXCEPTION ERROR ====================
// switch these two city variables to see a exception error occur
$city = 'Vancouver';
//$city = 'Gotham City';			// <--- this will result in an exception error when uncommented.

$db = new SQL($username,$password,$database);

/**
* try catch block.
* try - to connect to the database and once connected, disconnect.
* catch - any exception that will occur and kill the script.
*/
try {
	$db->connect();
	$db->disconnect();
} catch (SQLException $e) {
	$db->disconnect();
	die($e->getMessage());
}

/**
* try catch block
* try to connect to the database
* try to run a select query (note: to get an exception error change the city variable above)
* print the query
* disconnect
* catch any error that may occur.
*/
try {
	$db->connect();
	$r = $db->getCity($city);

	// print the results
	echo '<pre>';
		print_r($r);
	echo '</pre>';

	$db->disconnect();
} catch (SQLException $e) {
	$db->disconnect();
	die($e->getMessage());
}

?>

Conclusion

Exception handling is a fun subject. The possibilities of being able to recover from errors that might occur create endless possibilities when scripting, just don’t do what I do and leave it all to the bitter end!

I was tasked with a project at work in which I had to build a site that would be quite dynamic. The problem however was that I could not use a database to hold information. What I did (and something I would avoid if I could) was create a class that looks within a folder thats specified and builds an array off the files within the folder.

How it works

Reads a folder of files, breaks apart the file name by a specified “breaker”. It then creates a new array off the specified file name attributes

Demo

File setup:

include_once('FileDetail.class.php');
// a new object reference using an array for the parameter which specifies the file name attributes
// FileDetail(array(attributes));
$files = new FileDetail(array('id','movie','name','ext'));

// loadFiles(Folder, separator)
$files->loadFiles('test_files2','_');

// New variable to hold the file name array
$fileNames = $files->getFileNames();

// New Variable to hold the file details array
$fileDetails = $files->getFileDetails();

Testing the arrays:

// ========================================= EXAMPLE =========================================
echo '<h4>File Names Test 2</h4>';
echo '<pre>';
	print_r($fileNames);
echo '</pre>';

// ========================================= EXAMPLE =========================================
echo '<h4>File Details</h4>';
echo '<pre>';
	print_r($fileDetails);
echo '</pre>';

File Names

Array
(
    [0] => 01_wall-e_walle02.jpg
    [1] => 02_batman_joker02.jpg
    [2] => 02_wall-e_walle.jpg
    [3] => 04_batman_joker02.jpg
    [4] => 05_batman_joker.jpg
)

File Details

Array
(
    [0] => Array
        (
            [id] => 01
            [movie] => wall-e
            [name] => walle02
            [ext] => jpg
        )

    [1] => Array
        (
            [id] => 02
            [movie] => batman
            [name] => joker02
            [ext] => jpg
        )

    [2] => Array
        (
            [id] => 02
            [movie] => wall-e
            [name] => walle
            [ext] => jpg
        )

    [3] => Array
        (
            [id] => 04
            [movie] => batman
            [name] => joker02
            [ext] => jpg
        )

    [4] => Array
        (
            [id] => 05
            [movie] => batman
            [name] => joker
            [ext] => jpg
        )

)

Real World Example:

echo '<h4>Get files of a specific parameter</h4>';
echo '<h5> movie -> batman</h5>';
echo '<pre>';
	print_r($files->getFilesByKey('movie','batman'));
echo '</pre>';

Get files of a specific parameter (movies->batman)

Array
(
    [0] => Array
        (
            [id] => 02
            [movie] => batman
            [name] => joker02
            [ext] => jpg
        )

    [1] => Array
        (
            [id] => 04
            [movie] => batman
            [name] => joker02
            [ext] => jpg
        )

    [2] => Array
        (
            [id] => 05
            [movie] => batman
            [name] => joker
            [ext] => jpg
        )

)

Conclusion

The class can be used in many which ways whether it’s loading a gallery of images or building a website based off of the attributes of the images. The class and demo files can be downloaded here

A few weeks ago I had wrote Arrays and Loops with php [Level 1]. This topic is expanding on that idea. I’ll be covering more complex array examples using 2D multidimensional arrays.

Multidimensional Arrays

The idea of a multidimensional array is something that can easily confuse someone, especially when they become complex with information (ie. 2D and 3D arrays). I like to think of multidimensional arrays as a miniature database.

A multidimensional array can hold multiple values to a single key. Take a look at the output below.

Array
(
    [0] => Array
        (
            [name] => Cody
            [gender] => male
            [colour] => green
            [fruit] => apples
            [sport] => frisbee
        )

    [1] => Array
        (
            [name] => Sam
            [gender] => male
            [colour] => blue
            [fruit] => oranges
            [sport] => golf
        )

    [2] => Array
        (
            [name] => Jenny
            [gender] => female
            [colour] => pink
            [fruit] => pineapple
            [sport] => hockey
        )

)

This example is an example of a 2D array using key values. By default PHP will auto fill the keys, but this can lead to confusion down the road. To set up the array:

$people = array( array("name"=>"Cody",
						"gender"=>"male",
						"colour"=>"green",
						"fruit"=>"apples",
						"sport"=>"frisbee"),
				array("name"=>"Sam",
					"gender"=>"male",
						"colour"=>"blue",
						"fruit"=>"oranges",
						"sport"=>"golf"),
				array("name"=>"Jenny",
						"gender"=>"female",
						"colour"=>"pink",
						"fruit"=>"pineapple",
						"sport"=>"hockey")
				);

echo '<pre>';
	print_r($people);
echo '</pre>';

There’s a lot going on, take some time and read through it. First we set up a main container that will hold all of our information

$people

we then put a new array within our already created array.

Retrieving a single value is quite easy. We just call on what array element we want, then we ask for a specific property, in this example the name.

echo '<pre>';
echo $people[0]['name'];
echo '</pre>';

How this can be used

By looping of course! We can loop through this in many different ways to provide an example:

for ($i=0; $i<sizeOf($people); $i++) {
	$string = $people[$i]['name'] . "'s favorite fruit is " . $people[$i]['fruit'];
	if ($people[$i]['gender'] === "male") {
		$string .= " his favorite colour is " . $people[$i]['colour'] . " and he enjoys to play " . $people[$i]['sport'];
	}
	else if ($people[$i]['gender'] === "female") {
		$string .= " her favorite colour is " . $people[$i]['colour'] . " and she enjoys to play " . $people[$i]['sport'];
	}
	echo $string;
	echo '<br>';
}

output:

Cody's favorite fruit is apple his favorite colour is green and he enjoys to play frisbee
Sam's favorite fruit is oranges his favorite colour is blue and he enjoys to play golf
Jenny's favorite fruit is pineapple her favorite colour is pink and she enjoys to play hockey

Here I used a if statement within my for loop to check the gender value. If it were a male I had the output specify “he”, and the same check for a female.

Another use for a multidimensional array is a table layout, or grid.

$grid = array(array('Cody','male','green'),
			array('Sam','male','blue'),
			array('Jenny', 'female','pink')
);
for ($r=0; $r<sizeOf($grid); $r++) {
	for($c=0; $c<sizeOf($grid[$r]); $c++) {
		echo $grid[$r][$c]. " | ";
	}
	echo '<br>';
}

output:

Cody | male | green |
Sam | male | blue |
Jenny | female | pink |

Conclusion

multidimensional arrays make for an interesting topic, there is so much you can do, but without doing they can be hard to explain. Here is the source to help you get started.

<?php
$people = array( array("name"=>"Cody",
						"gender"=>"male",
						"colour"=>"green",
						"fruit"=>"apples",
						"sport"=>"frisbee"),
				array("name"=>"Sam",
					"gender"=>"male",
						"colour"=>"blue",
						"fruit"=>"oranges",
						"sport"=>"golf"),
				array("name"=>"Jenny",
						"gender"=>"female",
						"colour"=>"pink",
						"fruit"=>"pineapple",
						"sport"=>"hockey")
				);

echo '<pre>';
	print_r($people);
echo '</pre>';

// Get a single value
echo '<pre>';
echo $people[0]['name'];
echo '</pre>';
// ================================================= LOOP =================================================
for ($i=0; $i<sizeOf($people); $i++) {
	$string = $people[$i]['name'] . "'s favorite fruit is " . $people[$i]['fruit'];
	if ($people[$i]['gender'] === "male") {
		$string .= " his favorite colour is " . $people[$i]['colour'] . " and he enjoys to play " . $people[$i]['sport'];
	}
	else if ($people[$i]['gender'] === "female") {
		$string .= " her favorite colour is " . $people[$i]['colour'] . " and she enjoys to play " . $people[$i]['sport'];
	}
	echo $string;
	echo '<br>';
}

// ================================================= GRID =================================================
$grid = array(array('Cody','male','green'),
			array('Sam','male','blue'),
			array('Jenny', 'female','pink')
);
for ($r=0; $r<sizeOf($grid); $r++) {
	for($c=0; $c<sizeOf($grid[$r]); $c++) {
		echo $grid[$r][$c]. " | ";
	}
	echo '<br>';
}

?>

Way back when I started programming there were two things I just could not wrap my head around. Unfortunately they fell hand in hand which made doing an alternative quote tedious. Loops and arrays were nightmares. This post is outlines a few small pointers I’ve picked up along the way.

What is an array, what is a loop?

The best way to think of an array is as a container, or box. The box (array) can hold values and objects for safe keeping, we can put things into the box, and we can take them out. We do this by using a loop. The loop will cycle through the array, and within the loop we can perform actions to all the objects, a group of objects or any single object.

There are three types of loops are the for loop, the foreach, and the while loop. What loop to use and when I belive comes with experience and practice. The three loops are similar in what they do, but depending when you use them, or how they’re used is the tricky part.

Defining an Array

I stated earlier that an array was simply a collection of values or objects.

$fruits = array("apples", "oranges", "pears", "cherries");

Thats all there is to an array, I have it stored within a variable that acts as the container. Now how do we access these delicious fruits?

echo $fruits[0];
echo '<br>';
echo $fruits[1];
echo '<br>';
echo $fruits[2];
echo '<br>';
echo $fruits[3];

NOTE:This is not a loop but its a wonderful method to quickly print out all the elements within an array. I use this a lot when developing and debugging.

// print array
echo '<pre>';
	print_r($fruits); // print array
echo '</pre>';

outputs:

Array
(
    [0] => apples
    [1] => oranges
    [2] => pears
    [3] => cherries
)

What makes an array? You can see from the output above that there are two elements within the array [key]=>[value]. Each array element is assigned a unique key. The key is how we can call any given member within the array.

How do we add a new fruit? To add something to our array we call the array, and give it a new value in an empty index position (php will do the math for you)

$fruits[] = 'grapes';
$fruits[] = 'mango';

printing the array again we can now see that indeed our fruits have been added.

Array
(
    [0] => apples
    [1] => oranges
    [2] => pears
    [3] => cherries
    [4] => grapes
    [5] => mango
)

Working with loops

You might be asking yourself “Well how is that any easier then writing it out?”. Thats when loops become a handy tool, we can simply call any of the three loops to loop through the array and print everything within the array (opposed to printing them individually using $fruits[x])

foreach loop: Perhaps as far as this demo goes the minimalist and simplest loop. It basically iterates over each element and outputs its value.

// foreach
foreach ($fruits as $loop) {
	echo $loop;
	echo '<br>';
}
echo '<hr>';

The next two loops are similar in what they do. They both allow for more control within the loop allowing you to perform actions based on conditional statements.

for loop

// for loop
for ($i=0; $i<sizeOf($fruits); $i++) {
	echo $fruits[$i];
	echo '<br>';
}
echo '<hr>';

while loop

// while loop
$count = 0;
while ($count < sizeOf($fruits)) {
	echo $fruits[$count];
	echo '<br>';
	$count++;
}

Theres so much you can do with loops and still I struggle on getting things done with them. I wanted to keep this post simple, there are still multidimensional arrays which add a whole layer of complexcity to the topic. Hopefully I’ll continue this topic soon.

Heres the full script

<?php

// fruit array
$fruits = array("apples", "oranges", "pears", "cherries");

// getting the fruit
echo $fruits[0];
echo '<br>';
echo $fruits[1];
echo '<br>';
echo $fruits[2];
echo '<br>';
echo $fruits[3];

// print array
echo '<pre>';
	print_r($fruits); // print array
echo '</pre>';

// add to the array
$fruits[] = 'grapes';
$fruits[] = 'mango';

// print array
echo '<pre>';
	print_r($fruits); // print array
echo '</pre>';

// ================================================= LOOPS =================================================
echo '<hr>';

// foreach
foreach ($fruits as $loop) {
	echo $loop;
	echo '<br>';
}
echo '<hr>';

// for loop
for ($i=0; $i<sizeOf($fruits); $i++) {
	echo $fruits[$i];
	echo '<br>';
}
echo '<hr>';

// while loop
$count = 0;
while ($count < sizeOf($fruits)) {
	echo $fruits[$count];
	echo '<br>';
	$count++;
}
?>

• LIST ITEM

1. ORDER LIST ITEM

I tend to do a lot of work with database entry through PHP forums. Over time I've seen nemorous ways in which someone will enter their phone number.

The Problem

Because there are so many different ways to enter a phone number. How it's handled, processed and sent to the database becomes a challenge, and as a programmer you have to ask "what is the best way".

The Solution

The first solution would be to make your column in which will hold the phone number within your database a varchar(20). I suppose for something quick and dirty it will work, but in no means is this efficient.

The second solution would be to take a number:

• (555)555-5555
• 555.555.5555
• 555 555 5555
• 55 55 55 5555

and remove unneeded characters and insert it into the database as a int value of 5555555555

The class: