Handling "Undefined Index" in PHP with SYmfony - php

Question

I am building an app with Symfony 2, and I am wondering, how could I handle errors when I try to read a index in an array that doesn't exist? Sadly this kind of errors don't throw exceptions, so I can't really use a try-catch block.
Example:
$test = array();
$test["323"]; // Undefined index error!
Please, ideas how to handle this errors?
Update: I have seen many solutions with isset. The problem with this is that I would have to do it with every single access to an array index. Can anyone offer me a more DRY solution?

Answer 1

Both:
if(isset($test["323"])){
//Good
}
and
if(array_key_exists('123', $test)){
//Good
}
Will allow you to check if an array index is defined before attempting to use it. This is not a Symfony-specific error. Its a common PHP warning that occurs whenever you attempt to access an array element that doesn't exist.
$val = isset($test["323"]) ? $test["323"] : null;

Answer 2

An option would be to use set_error_handler() in order to, somehow, simulate exceptions. An example usage would be the following, although I'm sure you can adjust this to your specific use case:
function my_error_handler($errno,$errstr)
{
/* handle the issue */
return true; // if you want to bypass php's default handler
}
$test = array();
set_error_handler('my_error_handler');
$use_it=$test["323"]; // Undefined index error!
restore_error_handler();
You can see that we "wrap" our "critical" piece of code around set_error_handler() and restore_error_handler(). The code in question can be as little as a line, to as large as your whole script. Of course, the larger the critical section, the more "intelligent" the error handler has to be.

Answer 3

use array_key_exists(), like
if (array_key_exists('123', $test)) {
echo "it exists";
}

Answer 4

You can catch this bx surrounding it with isset:
if(isset($test["323"])){
//The value fo this key is set.
}

Answer 5

May be you wanted to achieve this ?
$test = array();
$test[]="323";
echo $test[0];//323

Answer 6

Simple way to try/catch undefined or many php errors.
try{
set_error_handler(function($errno, $errstr, $errfile, $errline, array $errcontext){
if (0 === error_reporting()) { return false; }
throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});
$data = $json['name']; ---> Undefined Index name
}catch(Exception $e){
//Perform Furthur action
}