How to prevent ob_start() output when an error occur? - php

Question

Please, consider the following example:
template.php:
<?php
echo $vars['arr'];
echo " -------- ";
echo $vars['obj'];
?>
test.php:
<?php
$file = "template.php";
$vars = array( 'arr' => array(), 'obj' => new StdClass() );
var_dump( json_encode($vars) );
function loadFile($file, $vars)
{
try
{
if (is_array($vars) && !empty($vars)) {
extract($vars);
}
ob_start();
include $file;
return ob_get_clean();
}
catch (Exception $e)
{
return false;
}
}
loadFile($file, $vars);
?>
This code will output:
string(19) "{"arr":[],"obj":{}}"
PHP Catchable fatal error: Object of class stdClass could not be converted to string in template.php
The problem here is, in the template.php I am considering $vars to be an array() however 1 of the elements is an Object as you can see from the json output.
Adding a simple checking in the template to verify if the ekement is an array or not would solve the problem, however I would need to this to multiple elements, elements, so, not very good =) so, I trying to find a way to prevent the error in the moment of binding the template and $vars.
Thank you

Answer 1

simply turn error_reporting off while parsing:
$old_level = error_reporting(0); // no errors, preserve old error reporting level
ob_start();
include $file;
$content = ob_get_clean();
error_reporting($old_level); // reset error reporting level
return $content;
Note: This will only hide errors that aren't very critical.
In order to catch a Catchable Fatal Error, see this question: How can I catch a "catchable fatal error" on PHP type hinting?
You need to register an error handler using set_error_handler:
function handleError($errno, $errstr, $errfile, $errline) {
// handle error
// return true, so the normal php handler doesn't get called
return true;
}
set_error_handler('handleError');
If you want to integrate you handler cleanly into other code which also sets error_handlers, you might consider restoring the error handler afterwards using restore_error_handler

Answer 2

You might try checking to see if the values are an object first, and then using the PHP function to convert to an array.
Note, this section of your code:
if (is_array($vars) && !empty($vars)) {
extract($vars);
}
After that, if I'm reading your code correctly, you have a variable possibly called $vars that could be an object. So, you could do this:
if (is_object($vars)) {
$vars = get_object_vars($vars);
}
That should convert it to what you need. Of course, you may need to experiment a bit to make sure it fits your scenario. Thanks!

Answer 3

You can use __toString() method in your class to avoid the error. You can set the __toString() method with any value you need, maybe return an array.
http://www.php.net/manual/en/language.oop5.magic.php#object.tostring
Another option, is use array_walk :
function checkObj(&$vars){
if (is_object($vars)) {
$vars = get_object_vars($vars);
}
}
array_walk($vars, "checkObj");

Answer 4

Since you are using ob_start(), you can pass it a call-back that will check for any errors. It should even work with fatal errors. Inside your call-back use something like "error_get_last" to check for any error and just return false if it's not null, like so:
WARNING: I've not tested this code, but I use something similar myself.
<?php
$file = "template.php";
$vars = array( 'arr' => array(), 'obj' => new StdClass() );
var_dump( json_encode($vars) );
function loadFile($file, $vars)
{
try
{
if (is_array($vars) && !empty($vars)) {
extract($vars);
}
ob_start('errorHandler');
include $file;
return ob_get_clean();
}
catch (Exception $e)
{
return false;
}
}
function errorHandler($pBuffer)
{
$lastError = error_get_last();
// Uh-oh, an error has occurred.
if ($lastError !== NULL)
{
return FALSE;
}
// No problems.
return $pBuffer;
}
loadFile($file, $vars);
?>