[12.x] Support nested relations on relationLoaded method

[tmsperera]

Added support to check nested relations when using relationLoaded() method of Eloquent Model

Why?

Current relationLoaded() method only checks single level relation of the Model. Now users can check nested relations.

$user->load('posts.comments');

// Previously
$user->relationLoaded('posts'); // true
$user->relationLoaded('posts.comments'); // false

// Now
$user->relationLoaded('posts'); // true
$user->relationLoaded('posts.comments'); // true

Benefits

End users can check whether the nested relation loaded once and load the desired relation.

It will not break existing features

Technically this new enhancement should not break any existing usage of the method because the code is designed to support single level relation check as well.

[rodrigopedra]

Adding type hinting to a method's argument, and adding a return type to a method, are breaking changes to anyone overriding this method in a subclass.

As all models extend the Model class, there is a non-zero chance some project might be overriding this method.

[tmsperera]

@rodrigopedra Yes having return type causes issues. Modified the code.

[rodrigopedra]

I would keep the current check on top of the method body to avoid any performance impact.

Something like this:

public function relationLoaded($key)
{
    if (array_key_exists($key, $this->relations)) {
        return true;
    }

    // augmented logic
}

[rodrigopedra]

I can't approve it, but looks good to me

[danharrin]

Hmm this does seem to have caused a problem for me, here's an open source test failure if you are interested: https://github.com/filamentphp/filament/actions/runs/14589554182/job/40966543141

[danharrin]

The issue is that the relationLoaded() method is not just called by users, it's also caused by the framework if you attempt to access an attribute that doesn't exist:

framework/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php

Line 485 in 3faeb07

return $this->isRelation($key) || $this->relationLoaded($key)

In this case, the issue is when attempting to access an attribute with a . in its name.

[rodrigopedra]

@tmsperera you might want to add an instanceof while iterating $this->$relation items here:

framework/src/Illuminate/Database/Eloquent/Concerns/HasRelationships.php

Lines 1088 to 1094 in 3faeb07

	if ($nestedRelation !== null) {
	foreach ($this->$relation as $related) {
	if (! $related->relationLoaded($nestedRelation)) {
	return false;
	}
	}
	}

Something like this:

if ($nestedRelation !== null) {
    foreach ($this->$relation as $related) {
        if (! $related instanceof Model) {
            return false;
        }

        if (! $related->relationLoaded($nestedRelation)) {
            return false;
        }
    }
}

[danharrin]

Issue opened with reproduction repository: #55518

[tmsperera]

@danharrin Great you found the bug. @rodrigopedra great job on the fix. I will add more test cases to avoid such unexpected bugs happens in future as well.

[AhmedAlaa4611]

Reverted in: dc5b445