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Debugging collection chains

A couple of weeks ago I published a blog post on how you can easily debug collections using a dd macro. Meanwhile my company released a package that contains that macro. In this post I’d like to introduce a new dump macro, recently introduced in the package, that makes debugging collection chain even easier.

Here’s what the dump macro itself looks like.

Collection::macro('dump', function () {
        ->each(function ($item) {
            (new Dumper)->dump($item);
    return $this;

So what the macro basically does is dumping any argument you give it to the screen together with the collection itself. The entire collection is returned, so you can further chain it. Sounds a little abstract, no? Easier said: this macro can be used to dump all the steps in your collection chain to the screen.

Let’s see it in action. Take a look this collection chain:

    ->dump('original collection')

    ->map(function(int $number) {
        return $number * 2;
    ->dump('multiplied by two')

    ->filter(function(int $number) {
        return $number > 3;
    ->dump('filtered higher than three')


Executing that chain results in this being displayed on the screen.

dump output

Displaying every transformation in the chain will make it much easier to find a potential bug. Hope you like it!

Freek Van der Herten is a partner and developer at Spatie, an Antwerp based company that specializes in creating web apps with Laravel. After hours he writes about modern PHP and Laravel on this blog. When not coding he’s probably rehearsing with his kraut rock band. He loves waffles and butterflies.