Order by Votes in Laravel ORM - php

Question

I have 3 Models... Category, Post, Vote
When viewing a category, I am showing an index of all Posts in that category. So I'm doing something like foreach ($category->posts as $post) in my view.
The question I have now is how can I order the posts based on the sum of votes they have?
I have standard relationships setup, so that a post hasMany votes.

Answer 1

You can do it either by defining a helper relation on the Post model and sorting the collection after the relation is loaded OR simply by joining the votes and ordering in the query.
1 RELATION
// Post model
public function votesSum()
{
return $this->hasOne('Vote')->selectRaw('post_id, sum(votes) as aggregate')->groupBy('post_id');
}
// then
$category->posts->load('votesSum'); // load relation on the collection
$category->posts->sortByDesc(function ($post) {
return $post->votesSum->aggregate;
});
// access votes sum like this:
$category->posts->first()->votesSum->aggregate;
2 JOIN
$category->load(['posts' => function ($q) {
$q->leftJoin('votes', 'votes.post_id', '=', 'posts.id')
->selectRaw('posts.*, sum(votes.votes) as votesSum')
->groupBy('posts.id')
->orderBy('votesSum', 'desc');
}]);
// then access votes sum:
$category->posts->first()->votesSum;
You can use scope for that:
// Post model
public function scopeOrderByVotes($query)
{
$query->leftJoin('comments','comments.post_id','=','posts.id')
->selectRaw('posts.*,sum(comments.id) as commentsSum')
->groupBy('posts.id')
->orderBy('commentsSum','desc');
}
// then
$category = Category::with(['posts' => function ($q) {
$q->orderByVotes();
}])->whereSlug($slug)->firstOrFail();