Framework: Eloquent doesn't need to execute relation query if foreign key is null

[cviebrock]

• Laravel Version: 5.4.28
• PHP Version: 7.1.4
• Database Driver & Version: MySQL 5.7.17

Description:

When the foreign key of a relation is null, then don't execute the SQL call when trying to load the relation.

Steps To Reproduce:

Assume the following Eloquent model that has an (optional) relationship (i.e. the author_id field is nullable):

class Post extends Model {

    /**
     * Relation to (optional) author model
     */
    public function author(): BelongsTo
    {
        return $this->belongsTo(User::class, 'author_id');
    }

    ...
}

If $post->author_id === null, then that post doesn’t have an author (duh!).

However, when I reference the relation with $post->author or $post->load('author'), then Laravel 5.4 is still tries to query the database. Using debugbar, I see:

select * from `users` where `users`.`user_id` in ('') and `users`.`deleted_at` is null

It seems to me that all the relation logic that gets executed -- and especially the SQL call -- could be skipped if the foreign key to a relation is null, no? Basically, if author_id is null, then just return null.

[decadence]

Makes sense

[MohannadNaj]

Sorry if I misunderstood the issue, but what if the null value in itself is an id (despite how bad this practice)? In that case, the returned value is the expected one.

[themsaid]

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

[cviebrock]

Will do, @themsaid. I did ask in the internals channel on slack whether this is a bug or new proposal, and it was suggested I post here. Sorry!

I'll repost over on the other repo.

[spaceemotion]

Had this today myself, https://github.com/laravel/ideas/issues/748#issuecomment-372791896 said that this should be considered a bug, not a feature, but this hasn't been reopened yet (and the duplicate has been closed). Would be nice to have this "fixed"!

[arthurlauck]

+1