The transform is identical to the map method, but instead of returning a new Collection instance, the transform method will modify the original collection instance. The transform method will return a reference to the original collection instance.

The behavior of both the transform and map functions can be thought as projecting the items in the collection into a new form; this can be useful for bridging method arguments for in compatible APIs, converting arrays to objects, etc.

#Signature

1public function transform(
2    callable $callback
3);

#Example Use

The following code example demonstrates the usage and behavior of the transform method:

 1use Illuminate\Support\Collection;
 2 
 3// Create a new collection instance.
 4$collection = new Collection([
 5    'first', 'second', 'third'
 6]);
 7 
 8// Modify the original and change the case of
 9// each string to upper-case.
10$collection->transform(function($item, $key) {
11    return strtoupper($item);
12});

After the above code example has executed, the $collection variable would would contain a value similar to the following output:

1object(Illuminate\Support\Collection)
2  protected 'items' =>
3    array
4      0 => string 'FIRST'
5      1 => string 'SECOND'
6      2 => string 'THIRD'

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