Performing a sum() on a collection in Laravel - php

Question

I have an application with a basic forum system where users can "like" a topic multiple times. My models extend Eloquent and I'm trying to get the sum of votes a user has for a specific topic... Basically, I'm trying to accomplish something like:
$votes = Auth::user()
->votes->has('topic_id', '=', $topic->id)
->sum('votes');
However, when executing this, I get the following error...
Call to a member function sum() on a non-object
I've also tried
public function show($forumSlug, $topicSlug)
{
$topic = Topic::whereSlug($topicSlug)->first();
$votes = Topic::whereHas('votes', function ($q) use ($topic)
{
$q->where('topic_id', '=', $topic->id)->sum('votes');
});
dd($votes);
}
However, with that I receive an error stating:
Unknown column 'ideas.id' in 'where clause' (SQL: select sum(votes)
as aggregate from votes where votes.idea_id = ideas.id and
idea_id = 1)`

Answer 1

You may try something like this (Not sure about your relationship but give it a try):
$topic = User::with(array('topics' => function ($query) use ($topic_id) {
// $query = Topic, so it's: Topic::with('votes')
$query->with('votes')->where('topics.id', $topic_id);
}))->find(Auth::user()->id)->topics->first();
// Count of total votes
dd($topic->votes->count());
P/S: If it doesn't work then please post your model's relationship methods.

Answer 2

I managed to get it working, though I'm not sure I like this approach. I'd love to hear if anyone knows of a better way of doing this...
Basically, I used my relationships to filter() the votes and then used sum() on the filtered collection.
public function show($forumSlug, $topicSlug)
{
$userId = is_null(Auth::user()) ? false : Auth::user()->id;
$topic = Topic::whereSlug($topicSlug)->first();
$votes = $topic->votes->filter(function ($votes) use ($userId)
{
return $votes->user_id == $userId;
})->sum('votes');
return View::make('forums.topics.show', compact('topic', 'votes'));
}