Merge Laravel collections keys in only string

You can use PHP implode() or Laravel ->implode() method on collection:

implode(',', $collection->toArray());

$collection->implode(',');

use implode https://laravel.com/docs/5.3/collections#method-implode

if $collection is the value you have shown then

dd($collection->implode(',')); should give the expected result

And if it's a multi-dimensional array, implode can also accept first arg as the key name:

$collection = collect([
  [ 'title' => 'Hello world' ],
  [ 'title' => 'Another Hello world' ]
]);

$collection->implode('title', ',')

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