symfony2 doctrine fetch while without creating complete array of results - php

Question

I am looking to export to a csv file using doctrine. However the data is likely to be quite large. Therefore I dont want to ouput to the results to a complete array. I want to traverse the results iteratively.
I have tried looking here
doctrine docs
The PHP looks something like this
$result = mysql_query("SELECT * FROM bigtable");
while($row = mysql_fetch_assoc($result)) {
// do code iteratively here
}
Not sure how you do the same thing in doctrine for symfony2

Answer 1

This is from the doctrine documentation about batch processing:
$q = $this->_em->createQuery('select u from MyProject\Model\User u');
$iterableResult = $q->iterate();
foreach ($iterableResult AS $row) {
// do stuff with the data in the row, $row[0] is always the object
// detach from Doctrine, so that it can be Garbage-Collected immediately
$this->_em->detach($row[0]);
}
'select u ....is the equivalent to your SELECT * ...

Answer 2

$result = mysql_query("SELECT * FROM bigtable");
while($row = mysql_fetch_assoc($result)) {
// do code iteratively here
}
is Flat PHP and symfony2/doctrine is designed to avoid it. http://symfony.com/doc/2.0/book/from_flat_php_to_symfony2.html

Answer 3

kudos to Dirk his answer is correct. If you want to iterat eover entity models then thats the way to go. Sometimes you may not have a model mapped setup for the sql results you are returning. If you want to do it over a raw sql file then this is how I did it. I would be interested to hear more thoughts.
You pass the doctrine connection into the class via your controller
Controller
function indexAction(){
$className = new ClassName($this->getDoctrine()->getEntityManager());
}
You can then create raw sql lookup
Entity
function __construct($entity){
$this->connection = $entity->getConnection();
}
function saveToCSV
{
$stmt = $this->connection->prepare("SELECT * FROM bitTableExample ");
$stmt->execute();
while($row = $stmt->fetch()){
// append to csv file
}
}