Why var_dump a Doctrine Objects kill my Apache?

Question

I have a very strange problem, when I try to var_dump (or print_r) a Doctrine Object, my Apache responses with an empty blank page (200 OK header). I can var_dump a normal php var like:

$dummy = array("a" => 1, "b" =>2);

And it works fine. But I can't with any object from any Doctrine class, (like a result from $connection->query(), or an instance of a class from my object model with Doctrine).

Anybody knows why this happens?

Answer 1

I've had that sometimes when trying to print_r() a self-referencing object - it gets into a loop and runs out of memory. Possibly that's what's happening to you.

Try increasing the memory limit (ini_set('memory_limit', '256M');) and see if that fixes it.

Edit: I don't think there's an actual fix for this - it's PHP's internal var_dump / print_r that don't limit depth on recursion (or don't do it properly, at least). If you install the XDebug extension, this can replace the built-in var_dump with a version that handles recursion much better.

Answer 2

Lazy load proxies always contain an instance of Doctrine’s EntityManager and all its dependencies.

Therefore a var_dump will possibly dump a very large recursive structure which is impossible to render and read. You have to use \Doctrine\Common\Util\Debug::dump() to restrict the dumping to a human readable level. Note that the default depth for this function is set to 2 (it's the second parameter)

Answer 3

Use the toArray method of the Doctrine_Record class

var_dump($doctrine_record->toArray());

will only display the DB fields and avoid dumping the complete Doctrine internals (which contains self reference/recursion btw)

Answer 4

You can use toArray if you are sure the object is an instance of Doctrine_Collection. Xdebug does not help with doctrine records.

The way I suggest is implementing a custom recursive function to print object, that use Doctrine_Record::toArray() when neeeded

function var_dump_improved()
{
   foreach (func_get_args() as $arg) {
       if ($args instanceof Doctrine_Collection) {
          print_r($arg);
       } else if ( $arg instanceof Traversable || is_array($arg) ) {
          // do a foreach and recall var_dump_improved on subelements
       } else if (...) {
          // other types
       } 
   }   
}

Some recursive function to debug with max nesting levels are here

http://php.net/manual/en/function.var-dump.php

Look at the comments, look for "recursion"