From a842cb3306a31d2627151753aafa883cc9bced12 Mon Sep 17 00:00:00 2001
From: Ian Littman <iansltx@gmail.com>
Date: Wed, 6 Mar 2019 19:05:07 -0600
Subject: [PATCH] Take N^2+1 queries down to N+1 via custom leaderboard query

---
 app/Challenge.php                            | 29 +++++++++-----------
 app/Http/Controllers/ChallengeController.php |  8 ++++--
 app/Query/ChallengeStats.php                 | 19 +++++++++++++
 3 files changed, 37 insertions(+), 19 deletions(-)
 create mode 100644 app/Query/ChallengeStats.php

diff --git a/app/Challenge.php b/app/Challenge.php
index b5e5307..88cb3c9 100644
--- a/app/Challenge.php
+++ b/app/Challenge.php
@@ -2,6 +2,7 @@
 
 namespace Challengr;
 
+use Challengr\Query\ChallengeStats;
 use Illuminate\Database\Eloquent\Model;
 
 /**
@@ -62,17 +63,15 @@ public function getLeaderboard()
 
     public function getDurationLeaderboard()
     {
-        $arr = $this->users_joined->map(function(User $user) {
+        $stats = ChallengeStats::getForChallenge($this->id);
+
+        $arr = $this->users_joined->map(function(User $user) use ($stats) {
             return [
                 'id' => $user->id,
                 'name' => $user->name,
-                'duration_seconds' => $durationInSeconds = $user->activities()
-                    ->whereBetween('started_at', [$this->starts_at, $this->ends_at])
-                    ->sum('duration'),
-                'distance_miles' => $user->activities()
-                    ->whereBetween('started_at', [$this->starts_at, $this->ends_at])
-                    ->sum('distance_miles'),
-                'duration' => Util::secondsToTime($durationInSeconds),
+                'duration_seconds' => $stats[$user->id]['duration'] ?? 0,
+                'distance_miles' => $stats[$user->id]['distance_miles'] ?? 0,
+                'duration' => Util::secondsToTime($stats[$user->id]['duration'] ?? 0),
             ];
         })->toArray();
         usort($arr, function ($a, $b) {
@@ -83,17 +82,15 @@ public function getDurationLeaderboard()
 
     public function getDistanceLeaderboard()
     {
-        $arr = $this->users_joined->map(function(User $user) {
+        $stats = ChallengeStats::getForChallenge($this->id);
+
+        $arr = $this->users_joined->map(function(User $user) use ($stats) {
             return [
                 'id' => $user->id,
                 'name' => $user->name,
-                'duration_seconds' => $durationInSeconds = $user->activities()
-                    ->whereBetween('started_at', [$this->starts_at, $this->ends_at])
-                    ->sum('duration'),
-                'distance_miles' => $user->activities()
-                    ->whereBetween('started_at', [$this->starts_at, $this->ends_at])
-                    ->sum('distance_miles'),
-                'duration' => Util::secondsToTime($durationInSeconds),
+                'duration_seconds' => $stats[$user->id]['duration'] ?? 0,
+                'distance_miles' => $stats[$user->id]['distance_miles'] ?? 0,
+                'duration' => Util::secondsToTime($stats[$user->id]['duration'] ?? 0),
             ];
         })->toArray();
         usort($arr, function ($a, $b) {
diff --git a/app/Http/Controllers/ChallengeController.php b/app/Http/Controllers/ChallengeController.php
index 6448c60..a1db750 100644
--- a/app/Http/Controllers/ChallengeController.php
+++ b/app/Http/Controllers/ChallengeController.php
@@ -15,9 +15,11 @@ class ChallengeController extends Controller
     public function forCurrentUser(Request $request)
     {
         return [
-            'created' => Challenge::whereUserId($userId = $request->user()->id)->orderByDesc('created_at')->get(),
-            'joined' => Challenge::whereHas('users_joined', function(Builder $builder) use ($userId) {
-                return $builder->whereKey($userId);
+            'created' => Challenge::with('users_joined')
+                ->whereUserId($userId = $request->user()->id)->orderByDesc('created_at')->get(),
+            'joined' => Challenge::with('users_joined')
+                ->whereHas('users_joined', function(Builder $builder) use ($userId) {
+                    return $builder->whereKey($userId);
             })->orderByDesc('ends_at')->get()
         ];
     }
diff --git a/app/Query/ChallengeStats.php b/app/Query/ChallengeStats.php
new file mode 100644
index 0000000..a7225cb
--- /dev/null
+++ b/app/Query/ChallengeStats.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace Challengr\Query;
+
+class ChallengeStats
+{
+    public static function getForChallenge($id)
+    {
+        $ret = [];
+        foreach (\DB::select(' select sum(activities.duration) duration, sum(activities.distance_miles) distance_miles,
+                activities.user_id from activities join challenge_user on challenge_user.user_id = activities.user_id
+                join challenges on challenges.id = challenge_user.challenge_id
+                where activities.started_at between challenges.starts_at and challenges.ends_at && challenges.id = ?
+                group by activities.user_id', [$id]) as $row) {
+            $ret[$row->user_id] = ['distance_miles' => $row->distance_miles, 'duration' => $row->duration];
+        }
+        return $ret;
+    }
+}