Question

我有一个“静态”模型。它包含带有有关其各种信息的游戏。用户可以评论具有多态关系的游戏。问题是我想获取已被评论的10个最新游戏，以及该评论的用户。因此，Game与Users没有关系。

我设法解决了这个问题

$games = Game::join('comments', 'games.id', '=', 'comments.commentable_id')
->where('comments.commentable_type', Game::class)
->latest('comments.created_at')
->groupBy('games.id')
->take(10)
->withCount('comments')
->get()->each(function($game){
    $game->comment = $game->comments()->orderBy('created_at', 'desc')->first();
    $game->user = User::find($game->comment->user_id);
    return $game;
});

但这会创建很多查询，我想急于加载，没有每个人都在谈论的N + 1问题。

我还有另一种解决方案，可以将此功能添加到Game

class Game extends Model {
    public function latestComment() {
        return $this->morphOne(Comment::class, 'commentable')->latest();
    }
}

运行查询$games = Game::withCount('comments')->with(['latestComment.user'])->take(10)->get();

但是似乎此查询无法获取用户。仅获取第一个用户。并且comments_count（withCount()）仅返回第一个结果的值。

所以我被卡住了！

预期结果 用该游戏的最新评论，该游戏的评论总数，用户的最新评论来加载10个最新游戏-渴望加载所有内容以避免n + 1问题。

有可能吗？ ps。准备了一个sqlfiddle http://www.sqlfiddle.com/#!9/c07570

修改似乎这个问题中的第二个查询“ takes”（take(10)）从游戏表中取出前10个游戏，无论它们是否有注释。如果我对ID为20-30的游戏有15条评论，则查询将检查ID为1到10的游戏。

如果我运行问题中的第二个查询，而注释表中只有小提琴数据。结果10将包含ID为10，没有用户，没有comments_count等的游戏。

Answer 1

您可以使用经过修改的import UIKit import Firebase import FirebaseAuth import FirebaseDatabase import MapKit class EmployeeTableViewController: UITableViewController, CLLocationManagerDelegate { @IBOutlet weak var jobsAvailableMap: MKMapView! var jobRequests : [DataSnapshot] = [] var locationManager = CLLocationManager() var employeeLocation = CLLocationCoordinate2D() override func viewDidLoad() { super.viewDidLoad() locationManager.delegate = self locationManager.desiredAccuracy = kCLLocationAccuracyBest locationManager.requestWhenInUseAuthorization() locationManager.startUpdatingLocation() Database.database().reference().child("JobRequests").observe(.childAdded) { (snapshot) in if let jobRequestDictionary = snapshot.value as? [String:AnyObject] { if let employeeLat = jobRequestDictionary["employeeLat"] as? Double { } else { self.jobRequests.append(snapshot) self.tableView.reloadData() } } } Timer.scheduledTimer(withTimeInterval: 3, repeats: true) { (timer) in self.tableView.reloadData() } } func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) { if let coord = manager.location?.coordinate { employeeLocation = coord } } override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { // #warning Incomplete implementation, return the number of rows return jobRequests.count } override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: "jobRequestCell", for: indexPath) let snapshot = jobRequests[indexPath.row] if let jobRequestDictionary = snapshot.value as? [String:AnyObject] { if let email = jobRequestDictionary["email"] as? String { if let lat = jobRequestDictionary["lat"] as? Double { if let lon = jobRequestDictionary["lon"] as? Double { let employeeCLLocation = CLLocation(latitude: employeeLocation.latitude, longitude: employeeLocation.longitude) let employerCLLocation = CLLocation(latitude: lat, longitude: lon) let distance = employeeCLLocation.distance(from: employerCLLocation) / 1000 let roundedDistance = round(distance * 100) / 100 cell.textLabel?.text = "\(email) - \(roundedDistance)km away" } } } } return cell } override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { let snapshot = jobRequests[indexPath.row] performSegue(withIdentifier: "acceptSegue", sender: snapshot) } override func prepare(for segue: UIStoryboardSegue, sender: Any?) { if let acceptVC = segue.destination as? AcceptJobViewController { if let snapshot = sender as? DataSnapshot { if let jobRequestDictionary = snapshot.value as? [String:AnyObject] { if let email = jobRequestDictionary["email"] as? String { if let lat = jobRequestDictionary["lat"] as? Double { if let lon = jobRequestDictionary["lon"] as? Double { acceptVC.requestEmail = email let location = CLLocationCoordinate2D(latitude: lat, longitude: lon) acceptVC.requestLocation = location acceptVC.employeeLocation = employeeLocation } } } } } } } @IBAction func logoutTapped(_ sender: Any) { try? Auth.auth().signOut() navigationController?.dismiss(animated: true, completion: nil) } }来获取最新的withCount()：

comments.created_at

Answer 2

我将直接访问评论表/模型，查询最近的10条评论，pluck游戏ID，并使用它们用whereIn查询游戏模型/表。

还向游戏查询中添加selectRaw('(SELECT COUNT(*) FROM comments where ...) as commentCount')

如何获取该特定模型的最新评论以及该评论的用户？

2 个答案: