Circular reference when loading relations

[nuzkito]

• Laravel Version: 5.4
• PHP Version: all
• Database Driver & Version: -

Description:

Suppose a post has many comments

class Post extends Model
{
    public function comments()
    {
        return $this->hasMany(Comment::class);
    }
}

and a comment belongs to a post

class Comment extends Model
{
    public function post()
    {
        return $this->belongsTo(Post::class);
    }
}

You can get a post with comments doing

$post = Post::with('comments')->find($id);

but then, if you iterate comments and use the post of the comment,

// Example. Suppose that this can be more complex and you can't simply pass $post to doSomenthingWithComment.
function doSomethingWithComment($comment) {
    chechkSomePostCondition($comment->post);
}

foreach ($post->comments as $comment) {
    doSomenthingWithComment($comment);
}

Eloquent will make a new query to the database for each $comment->post

select * from `posts` where `posts`.`id` = '33' limit 1;
select * from `posts` where `posts`.`id` = '33' limit 1;
select * from `posts` where `posts`.`id` = '33' limit 1;
...

But $comment->post is the same post that $post.

To avoid multiple queries you can do

$post = Post::with('comments.post')->find($id);

but this still creates an extra query

select * from `posts` where `id` = '33' limit 1; -- Query from Post::find.
select * from `posts` where `posts`.`id` in ('33'); -- Query from eager loading.

Is it possible for posts and comments to have a circular reference between them to avoid the second query? In this example you can simulate it doing

foreach ($post->comments as $comment) {
    $comment->post()->associate($post);
}

but can be this done with Eloquent directly?

[themsaid]

For suggestions and feature requests please use the https://github.com/laravel/internals repo.

Thanks :)