[5.3] Use intersect instead of only in the request helper

[JosephSilber]

request()->only() is a little weird, in that it returns null for missing values:

// $_POST === ['a' => 1, 'c' => 3];

request()->only('a', 'b'); // ['a' => 1, 'b' => null]

This is quite weird, as array_only skips missing values completely. I guess it's too late to change Request@only now, so a while ago the intersect method was added, which mimics array_only:

// $_POST === ['a' => 1, 'c' => 3];

request()->intersect('a', 'b'); // ['a' => 1]

This is the behavior you'd want most of the time. Imagine you're sticking stuff into the database:

$post->update(request(['title', 'body', 'date']));

If the user hasn't provided one of those properties, you definitely do not want to set those to null!

[GrahamCampbell]

I prefer only. It guarantees all the keys will exist.

[taylorotwell]

Eh, this seems like personal preference to me. If we change this, no doubt someone will come along who expected the other behavior and who is to say who is correct in that situation?