PHP Caching not working on Included File

Question

I have a web form that has an included file that outputs select options for states. The html looks like

    <select name="state" id="state">
        <option value="">--</option>
        <?php include ("resources/data/stateoptions.php"); ?>
      </select>

The state options makes a call to a web service so that the list of store locations is always current. It seems however that this contact form page runs exceptionally slow (much faster if I remove this include). So I want to cache the web service call. My state options file looks like this

<?php
  $cachefile = "cache/states.html";
  $cachetime = 5 * 60; // 5 minutes

  // Serve from the cache if it is younger than $cachetime
  if (file_exists($cachefile) && (time() - $cachetime < filemtime($cachefile))) 
  {
     include($cachefile);

     echo "<!-- Cached ".date('jS F Y H:i', filemtime($cachefile))." 
     -->n";

     exit;
  }

  ob_start(); // start the output buffer
?>

<?php
//url of locations web service
$serviceURL = 'http://webserviceurl/state';

//query the webservice
$string = file_get_contents($serviceURL);

//decode the json response into an array
$json_a=json_decode($string,true);

foreach( $json_a as $State => $IdealState){
$IdealState = $IdealState[State];
$IdealState2 = str_replace(' ', '-', $IdealState);
echo '<option value='.$IdealState2.'>'.$IdealState.'</option>';
}
?>

<?php
// open/create cache file and write data
$fp = fopen($cachefile, 'w'); 
// save the contents of output buffer to the file
fwrite($fp, ob_get_contents()); 
// close the file
fclose($fp); 
// Send the output to the browser
ob_end_flush(); 
?>

When I call this file directly, everything works as expected, and a states.html file is created. For some reason however when the stateoptions.php file is included in my contact form page, it never creates a cache file, and the speed problem persists. I'm a fairly novice programmer, so any help would be much appreciated.

Thanks!

Answer 1

The problem here is most likely going to be relative paths and working directories. The included file inherits its working directory from the calling script, it does not get a working directory of the location in which it resides automatically.

You either need to use the something like the magic __DIR__ constant to construct an absolute path, or adjust the relative path accordingly.

I'm going to go out on a limb a little bit here and say that if you change the first line to:

$cachefile = "resources/data/cache/states.html";

...you will probably find it works at you expect it to.