Vfrdtyky

I have a problem with the code below. I do not understand how it works. I come from java background and this function seems weird to me. In the first parameter it returns the result and in the second parameter it returns a list.

 private static function getEventsOfTheCampaigns($campaigns)

        {

            $events = Utility::arrayToCollection(array_map(function ($id) {

                return Events::find($id);

            }, array_unique(Utility::getIndexFromCollection($campaigns, 'event_id'))));

            return $events;

        }

defintion of the functions is below

 public static function arrayToCollection(array $list){



    $result = collect();



    if( !is_null($list) ):



        if(is_array( $list ) and count($list) > 0):



            foreach($list as $item):



                $result->push($item);



            endforeach;



        endif;



    endif;



    return $result;

}

can somebody explain me how it works? thanks.

Here's what happens when you run getEventsOfTheCampaigns() step-by-step:

1. $campaigns is passed first to Utility::getIndexFromCollection(). You didn't post the code, so I'm not sure what that function does, but based on what comes next, I'm assuming it returns an array of event IDs.




2. The result of (1) is passed to array_unique(). That would filter out any duplicate values in the array: http://php.net/manual/en/function.array-unique.php




3. The filtered array from (2) is passed as the 2nd parameter to array_map() which iterates over the array, performs the given callback function on each element, and returns a new array with values that result from the callback. The first parameter to array_map() is the callback function which, in this case, returns Events::find($id). So the result would be an array containing all the events that it found. http://php.net/manual/en/function.array-map.php




4. The array of events from (3) is then passed to Utility::arrayToCollection(), and that function looks like it takes the array and puts all the elements into a collection.




5. The collection of events is returned.

But the function could make better use of Laravel's collection methods. You can turn an array into a collection by passing it to the collect() function:

https://laravel.com/docs/5.7/collections

For example:

private static function getEventsOfTheCampaigns($campaigns)

{

    // if $campaigns is not a collection, you can turn it into one like this:

    // $campaigns = collect($campaigns);



    // pluck the event_id from $campaigns

    $eventIds = $campaigns->pluck('event_id');



    // this is not required for what happens next, but you can filter the IDs if you want to

    // $eventIds = $eventIds->unique()->values();



    // if you pass a collection or array to the `find()` method, $events will be a collection by default

    $events = Events::find($eventIds);  



    return $events;

}