Polymorphic relations in Laravel 4 - morphOne()

Question

Im having trouble creating a polymorphic relationship between two models:

• Upload
• Group

Simplified version of Group Model:

use Cartalyst\Sentry\Groups\Eloquent\Group as SentryGroupModel;

class Group extends SentryGroupModel {

  ...

  /**
   * returns the logo (upload model) from this agency
   *
   * @return Upload
   */
  public function logo()
  {
      return $this->morphOne('Upload', 'uploadable', 'model_type', 'model_id');
  }  

  ...

}

Simplified version of the Upload model

class Upload extends Eloquent {

  ...

  /**
   * returns the polymorphic relationship
   *
   * @return Upload
   */
  public function uploadable()
  {
      return $this->morphTo('uploadable', 'model_type', 'model_id');
  }  

  ...

}

As you can see the Group model is actually an extended Sentry 2 Group model, which is intern an extended Eloquent model.

When calling the relationship in a controller as such:

$agencyGroup->logo->saveUpload('logo');

i get the PHP error:

Call to a member function saveUpload() on a non-object

Any help with this?

Answer 1

The function logo() returns a MorphOne relationship and, since there's no method called saveUpload defined o MorphOne , it redirects the call to its Builder , which also doesn't have the method and throws the second exception you are experiencing:

Call to undefined method Illuminate\\Database\\Query\\Builder::saveUpload()

That behavior is expected and it's the way Eloquent works. That's why you should use just logo without () as you were trying in the first place.

Although, your $agencyGroup may not have a logo, which causes the NULL->saveUpload() I've mentioned and throws the first exception:

Call to a member function saveUpload() on a non-object

Try simply adding this on your controller:

if (empty($agencyGroup->logo)) {
    var_dump("There's no logo.");
    die();
}

$agencyGroup->logo->saveUpload('logo');

If you see the message "There's no logo", it means you should first create one logo before calling it's saveUpload method.