How to Order Laravel Results by Relationship Count?

Laravel: Order Results by Relationship Count

Ordering database results by the count of related records in a many-to-many relationship can be a complex task. Let's explore a solution for such a scenario.

Consider the following database schema:

hackathons
    id
    name
    ...

hackathon_user
    hackathon_id
    user_id

users
    id
    name

To retrieve the most popular hackathons based on the number of participants, we need to use a join query and group the results by hackathon ID, counting the number of participants for each hackathon. This can be achieved using the following query:

$hackathons = DB::table('hackathons')
    ->join('hackathon_user', 'hackathon_user.hackathon_id', '=', 'hackathons.id')
    ->groupBy('hackathon_user.hackathon_id')
    ->select('hackathons.id', 'hackathons.name', DB::raw('COUNT(*) as participant_count'))
    ->orderBy('participant_count', 'desc')
    ->get();

This query will fetch the hackathons ordered by the participant count, with the most popular hackathon listed first.

Alternatively, if using Laravel's Eloquent ORM, you can use the following approach:

Hackathon::withCount('participants')->orderBy('participants_count', 'desc')->get();

This approach is more convenient and straightforward, but it relies on Eloquent's withCount() method, which may not be available in older versions of Laravel.

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