Optional polymorphic relation results in fatal error

[schickling]

At the moment if you use polymorphic relations there always has to be a relation, otherwise an error occurs PHP Fatal error: Class name must be a valid object or a string. Thats clear since the implementation of the morphTo method looks up for a class of type xy. If no such is provided it results in an error.

For "normal" relations if two models are allowed to be in a relation but they aren't thats fine. The same behavior would be nice for polymorphic relations.

Example (from docs):

class Photo extends Eloquent {

    public function imageable()
    {
        return $this->morphTo();
    }

}

class Staff extends Eloquent {

    public function photos()
    {
        return $this->morphMany('Photo', 'imageable');
    }

}

If a Photo would be not in a relationship with a Staff model and just "lives on his own", that should be possible two and not result in an error.

[greggilbert]

+1. Got the same thing, only I'm using $this->morphOne() instead of morphMany.

[schickling]

I'm glad to know I'm not the only one facing this issue!

[ShawnMcCool]

Yea, optimally this would return an empty collection.

[taylorotwell]

I'm confused. What is happening? imagable should just return null, right? But you're saying it errors? Am I understanding that correctly?

[schickling]

Yes. In case of morphOne it should return null, in case of morphMany it should return an empty collection.

[taylorotwell]

Well the problem is really with morphTo right?

[schickling]

Yeah, sorry my bad

[driesvancraen]

I'm having the same issue here.. Any solutions?

[ShawnMcCool]

This is just a fundamental part of morphTo(). You can't create the morphTo object without already having a direct mapping to the target model.

You can create a setter that does something like:

$model->setSubject($thread);

Which then does something like..

public function setSubject($subject)
{
    $this->subject_id = $subject->getKey();
    $this->subject_type = get_class($subject);
}