Laravel count-function in Model, then sortBy count() - php

Question

I am trying to Order the Posts table by the number of votes a Post has got.
The votes are stored in an other table
(Votes: post_id, user_id, vote_type)
Post-Model:
class Post extends Model
{
public function user()
{
return $this->hasOne(User::class);
}
public function votes()
{
return DB::table('votes')->where('post_id','=',$this->id)->sum('vote_type');
}
}
The votes functions returns the number of votes a post has recieved(The Votes a stored in a seperate table)
Now I am trying to order all the Posts by the number of votes they have got.
Post::get()->sortBy('votes');
This returns follwing Error:
Relationship method must return an object of type Illuminate\Database\Eloquent\Relations\Relation
I would be thankful about any help to fix this!

Answer 1

give it a try
Post::get()->sortBy(function($query){
return $query->votes();
});
Alternative
You can use withCount() as it will place a {relation}_count column on your resulting models.
Post::withCount(['votes'])
->orderBy('votes_count')
->get()
For Pagination
Refer docs for more details on paginations
Post::withCount(['votes'])
->orderBy('votes_count')
->paginate();

Answer 2

Add the following function in your Post Model
protected static function boot()
{
parent::boot();
static::addGlobalScope('voteCount', function ($builder) {
$builder->withCount('votes');
});
}
Now, each of your post model will always have a voteCount value and You can sort on that.
In your controller, use:
Post::get()->sortBy('voteCount');
Keep in mind that this will always return a votesCount with the PostModel, but I'm assuming it will be required as it usually does in this kind of applications.

Answer 3

If you want to sort votes as a attribute you have to to make it to be attribute by adding getVotesAttribute() method in your Post Model.
class Post extends Model
{
public function user()
{
return $this->hasOne(User::class);
}
public function getVotesAttribute()
{
return DB::table('votes')->where('post_id','=',$this->id)->sum('vote_type');
}
}