Return new collection without modifying original collection

Question

I have a Laravel collection and I want to modify one of its property value to negative integer. For this I am using the collection map method but it also modifying the original collection.

My code:

$modified_revenue_data = $revenue_data->map(function ($item) {
    if ($item->is_claw_back == 1 && $item->claw_back_date != null) {
        return $item->revenue = $item->revenue * -1;
    }

    return $item;
});

I want to store the new collection into $modified_revenue_data but $revenue_data is also modified.

What would be the correct way of doing it without modifying the original collection?

Answer 1

It doesn't update the original collection:

$original = collect([1, 2, 3, 4, 5]);

$modified = $original->map(function ($el) {
     return $el * 2; 
});

dd($modified);

=> Illuminate\Support\Collection {#3726
     all: [
       2,
       4,
       6,
       8,
       10,
     ],
   }

dd($original);

=> Illuminate\Support\Collection {#3743
     all: [
       1,
       2,
       3,
       4,
       5,
     ],
   }

This behaviour is also stated in the documentation:

map()

...

Like most other collection methods, map returns a new collection instance; it does not modify the collection it is called on. If you want to transform the original collection, use the transform() method.