I am trying to call Eloquent's save() method on an existing record but getting an error from Illuminate's Query Builder.

Following the documentation on Laravel's web site at <http://laravel.com/docs/eloquent#insert-update-delete> for updating a retrieved model, and also looking at the example here: [Laravel Eloquent ORM save: update vs create](https://stackoverflow.com/questions/19684925/laravel-eloquent-orm-save-update-vs-create), my code appears to follow the expected convention, but instead I get the error mentioned in the title of this post.

```
$this->employee                  = Employee::where('login', $login);
$this->employee->first_name         = 'John';
$this->employee->last_name          = 'Doe';
$this->employee->save();

```

The Employee class extends Eloquent, and if I create a new instance of the model and then set some attributes and then call the save() method it performs the insert statements just fine. What am I missing?