corcel: Post method __get extremely slow

I have had a similar issue where the database was being hit when you would do the following:

$post = Post::query();

Which you might want to do start a fresh query chain. You’d end up with queries like this:

select 
  * 
from 
  `wp_postmeta` 
where 
  `wp_postmeta`.`post_id` is null 
  and `wp_postmeta`.`post_id` is not null

That will return an empty set, of course, but it’s still unnecessary to hit the database when you know it shouldn’t be returning anything, as is the case where you have a new instance of Post and no ID to go along with it.

I’ve created two patches with potential solutions to the issue and since they might intersect with some of the issues here I figured I’d post the patches here rather than start a new issue ticket.

• https://github.com/dark-panda/corcel/tree/dont-fetch-meta-on-null-with-pass-through - in this case, if we don’t have an ID yet, we just pass the __get up to parent.
• https://github.com/dark-panda/corcel/tree/dont-fetch-meta-on-null-with-set-new-meta-collection - in this case, we instantiate a new PostMetaCollection and assign it to the Post to mimic what we would have received from the database if we did have an ID.

I’m more partial to the second solution, but neither of them are perfect. I just figured I’d post them here for discussion to see if anyone had a better solution;