Query hasMany relation with slug instead of id? - laravel

Question

I'm trying to query a category and all of its channels based on a slug.
Works
\App\Category::find(1)->channels()->get();
Doesn't Work
\App\Category::where('slug','animals')->channels()->get()
BadMethodCallException with message 'Method Illuminate/Database/Query/Builder::channels does not exist.'
Relationship on Category Model
public function channels()
{
return $this->hasMany(Channel::class,'category_id');
}

Answer 1

Assuming that you correctly have your slug field set-up in migration and model attributes (It looks like so from the Exception message).
Doing
\App\Category::find(1)->channels()->get();
is under the hood equivalent to
\App\Category::where('category_id', 1)->first()->channels()->get();
So what you are requiring, is to get the categories to actually execute the query and then be able to retrieve the channels from the hydrated model.
\App\Category::where('slug', 'animals')->first()->channels()->get();
should work as well as
\App\Category::where('slug', 'animals')->first()->channels; // calling as attribute will perform the get() on the relationship
Also take note that you may take advantage of other methods like with() for eager loading the relationship, first() to perform a get and ensure you take only one instance, and calling the relationship as attribute as shown above. Refer to the docs

Answer 2

there are so many possible answer in your question .. be more specific .. but here's the list of sample queries that may help you ..
GETTING ALL THE CATEGORY WITH ITS CHANNELS WHERE CATEGORY SLUG = ANIMAL
Category::with(['channels'])->where('slug', 'animal')->get();
GETTING ALL THE CATEGORY WITH ITS CHANNELS WHERE HAS A CHANNEL SLUG = ANIMAL
Category::with(['channels'])->whereHas('channels'=>function($q){
$q->where('slug','animal');
})->get();
GETTING ALL THE CATEGORY WITH ONLY CHANNELS THAT HAS A SLUG = ANIMAL
Category::with(['channels'=>function($q){
$q->where('slug','animal');
}])->get();