load default image if database connection fails - php

Question

I am attempting to build a database driven site whereby images are loaded via a php script like so;
<img src="get_image.php?holderID=2">
I can get images to load from a folder outside the root directory when the database is accessible but I also want to be able to load a default image if there is a failure with making the database connection. The DB connection is initiated form a separate php connection file mysqli_template_connect.php;
DEFINE('DB_USER', 'someusername');
DEFINE('DB_PASSWORD', 'amnesia');
DEFINE('DB_HOST', 'localhost');
DEFINE('DB_NAME', 'template');
$dbc = #mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);
and then config.inc.php sets some constants, one of which is for all DB connections;
define('MYSQL', '../../../dbconnect/mysqli_template_connect.php');
The get_image.php file then has a database connection conditional;
require('includes/config.inc.php');
REQUIRE(MYSQL);
$holderID = $_GET['holderID'];
if(!$dbc){
$image_name = 'img/unavailable.png';
$info = getimagesize($image_name);
header("Content-Type: {$info['mime']}\n");
readfile($image_name);
}
else {
$query = "SELECT imageID FROM image_holder WHERE image_holderID = $holderID ";
$result = #mysqli_query($dbc, $query);
$number_rows = mysqli_num_rows($result);
if ($number_rows == 1) {
$row = mysqli_fetch_array($result, MYSQLI_NUM);
$imageID = $row[0];
}
else {
$imageID = FALSE;
}
if ($imageID) {
$query = "SELECT file_name FROM image WHERE imageID = $imageID";
$result = mysqli_query($dbc, $query);
$number_rows = mysqli_num_rows($result);
if ($number_rows == 1) {
$row = mysqli_fetch_array($result, MYSQLI_NUM);
$image_name = '../../../uploads/' . $row[0];
}
else {
$image_name = 'img/unavailable.png';
}
}
else {
$image_name = 'img/unavailable.png';
}
$info = getimagesize($image_name);
header("Content-Type: {$info['mime']}\n");
readfile($image_name);
mysqli_close($dbc);
}
If I disable the MYSQL database in XAMP, the default image unavailable.png will not load even though the header and readfile section of code is virtually the same in the section of code that does work. I'm quite a newbie to all this so any ideas on loading the default image would be appreciated.

Answer 1

Depending on the database object you are using (MySQLi/PDO/etc), you can check if they connected. PDO returns a boolean that you can run against.
Since PDO is the most popular, I will provide an example of that. If you use something else, feel free to comment and I can clarify.
$connected = true;
if (!extension_loaded('PDO'))
{
$connected = false;
}
if (!extension_loaded('pdo_mysql'))
{
$connected = false;
}
try
{
$pdo = new PDO("mysql:host={$host};dbname={$db}", $user, $pass);
}
catch(PDOException $e)
{
$connected = false;
}
if(!$connected){ /* Load default image */ }
Note: just make sure you use the correct image headers.

Answer 2

Instead of
$dbc = #mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);
Use
$dbc = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);
hopefully it should work..

Answer 3

I have similar code that do the almost the same thing.
I suspect it was the header, since I have a bit more info added to the header. No harm for you to try out.
header('Content-Description: File Transfer');
header('Content-Type: '. $file_content_type);
header('Content-Length: ' . filesize($file_full_path));
header('Content-Disposition: inline; filename=' . $file_name);
readfile($file_full_path);