How to chunk results from a custom query with Laravel 5

Question

Following up on this Question: How to chunk results from a custom query in Laravel

I try

DB::connection('mgnt')->select($query)->chunk(200, function($orders) {
    foreach ($orders as $order) { 

    //a bunch of code...

    }
});

But I get the following error:

FatalErrorException in MigrationController.php line 98:
 Call to a member function chunk() on array

Is chunking possible without having an appropriate Eloquent ORM Model? I try to chunk because I get a blank page (can't find any errrors in any log) if the query returns too many results.

I think right now it max 50.000 results that I can query at once. Is that maybe due to some restriction or limitation in Laravel?

Solution

Well since the query will just return an array of objects you can simply use PHP's array_chunk():

$result = DB::connection('mgnt')->select($query);
foreach(array_chunk($result, 200) as $orders){
    foreach($orders as $order){
        // a bunch of code...
    }
}

---

Here's what chunk() on an eloquent model does:

$results = $this->forPage($page = 1, $count)->get();

while (count($results) > 0)
{
    // On each chunk result set, we will pass them to the callback and then let the
    // developer take care of everything within the callback, which allows us to
    // keep the memory low for spinning through large result sets for working.
    call_user_func($callback, $results);

    $page++;

    $results = $this->forPage($page, $count)->get();
}

You could try to do something similar (although I think it should be possible to run your query all at once, but I can't help you with that...)

1. Add a limit to your SQL query LIMIT 200
2. Increase the offset with every query you run. First 0, second 1 * 200, third 2 * 200
3. Do that until the result is returned empty (e.g. with a while loop like above)