Zal*_*oza 43 php mysql notifications triggers
我想为我们学校实施一个通知系统,它是一个不为公众开放的php/mysql webapp,因此它不会收到太多流量."每日500-1000名访客".
1.我最初的方法是使用MYSQL触发器:
我使用Mysql AFTER INSERT trigger将记录添加到名为的表中notifications.就像是.
'CREATE TRIGGER `notify_new_homwork` AFTER INSERT ON `homeworks`
FOR EACH ROW INSERT INTO `notifications`
( `from_id`, `note`, `class_id`)
VALUES
(new.user_id,
concat('A New homework Titled: "',left(new.title,'50'),
'".. was added' )
,new.subject_id , 11);'
这种黑魔法工作得非常好,但我无法跟踪这个通知是否是新的"显示用户新通知的数量".所以我添加了一个名为notification的页面.
通过类似的方式检索通知
SELECT n.* from notifications n
JOIN user_class on user_class.class_id = n.class_id where user_class.user_id = X;
注意:表user_class将用户链接到类"user_id,class_id,subject_id"-subject为null,除非用户是教师'
现在我的下一个挑战是.
例如,如果2个用户对某些内容发表了评论,那么就不要插入新行,只需使用"userx和其他1个在hw上注释"的内容更新旧行.
非常感谢
编辑
根据下面的答案,要在行上设置读/未读标志,我需要为每个学生设置一行而不仅仅是整个类的一行..这意味着将触发器编辑为类似
insert into notifications (from_id,note,student_id,isread)
select new.user_id,new.note,user_id,'0' from user_class where user_class.class_id = new.class_id group by user_class.user_id
Mar*_*rio 131
那么这个问题是9个月大,所以我不确定OP是否仍然需要答案,但由于许多观点和美味的赏金,我还想添加我的芥末(德语说..).
在这篇文章中,我将尝试制作一个关于如何开始构建通知系统的简单解释示例.
编辑:好吧,这样,方式,方式,比我预期的方式更长.我到底累得累,对不起.
问题1:每个通知都有一个标志.
问题2:仍然将每个通知存储为数据库中的单个记录,并在请求时将它们分组.
我假设通知看起来像:
+---------------------------------------------+
| ? James has uploaded new Homework: Math 1+1 |
+---------------------------------------------+
| ? Jane and John liked your comment: Im s... |
+---------------------------------------------+
| ? The School is closed on independence day. |
+---------------------------------------------+
在窗帘后面,这看起来像这样:
+--------+-----------+--------+-----------------+-------------------------------------------+
| unread | recipient | sender | type | reference |
+--------+-----------+--------+-----------------+-------------------------------------------+
| true | me | James | homework.create | Math 1 + 1 |
+--------+-----------+--------+-----------------+-------------------------------------------+
| true | me | Jane | comment.like | Im sick of school |
+--------+-----------+--------+-----------------+-------------------------------------------+
| true | me | John | comment.like | Im sick of school |
+--------+-----------+--------+-----------------+-------------------------------------------+
| false | me | system | message | The School is closed on independence day. |
+--------+-----------+--------+-----------------+-------------------------------------------+
注意:我不建议将通知分组到数据库中,在运行时执行此操作可以使事情更加灵活.
我一直在研究的每个系统在通知上都有一个简单的1对1引用关系,你可能会记住1到1我将以1:1继续我的例子.这也意味着我不需要定义引用哪种类型对象的字段,因为这是由通知类型定义的.
现在,在为SQL定义真正的表结构时,我们就数据库设计做出了一些决定.我会选择最简单的解决方案,看起来像这样:
+--------------+--------+---------------------------------------------------------+
| column | type | description |
+--------------+--------+---------------------------------------------------------+
| id | int | Primary key |
+--------------+--------+---------------------------------------------------------+
| recipient_id | int | The receivers user id. |
+--------------+--------+---------------------------------------------------------+
| sender_id | int | The sender's user id. |
+--------------+--------+---------------------------------------------------------+
| unread | bool | Flag if the recipient has already read the notification |
+--------------+--------+---------------------------------------------------------+
| type | string | The notification type. |
+--------------+--------+---------------------------------------------------------+
| parameters | array | Additional data to render different notification types. |
+--------------+--------+---------------------------------------------------------+
| reference_id | int | The primary key of the referencing object. |
+--------------+--------+---------------------------------------------------------+
| created_at | int | Timestamp of the notification creation date. |
+--------------+--------+---------------------------------------------------------+
或者对于懒惰的人来说,这个例子的SQL create table命令:
CREATE TABLE `notifications` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`recipient_id` int(11) NOT NULL,
`sender_id` int(11) NOT NULL,
`unread` tinyint(1) NOT NULL DEFAULT '1',
`type` varchar(255) NOT NULL DEFAULT '',
`parameters` text NOT NULL,
`reference_id` int(11) NOT NULL,
`created_at` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
此实现完全取决于应用程序的需求.注意:这是一个示例,而不是如何在PHP中构建通知系统的黄金标准.
这是通知本身的示例基本模型,没有任何内容只是所需的属性和抽象方法messageForNotification,messageForNotifications我们期望在不同的通知类型中实现.
abstract class Notification
{
protected $recipient;
protected $sender;
protected $unread;
protected $type;
protected $parameters;
protected $referenceId;
protected $createdAt;
/**
* Message generators that have to be defined in subclasses
*/
public function messageForNotification(Notification $notification) : string;
public function messageForNotifications(array $notifications) : string;
/**
* Generate message of the current notification.
*/
public function message() : string
{
return $this->messageForNotification($this);
}
}
你必须以自己的风格自己添加一个构造函数,getter,setter和那种东西,我不打算提供一个随时可用的Notification系统.
现在,您可以Notification为每种类型创建一个新的子类.以下示例将处理注释的类似操作:
示例实现:
namespace Notification\Comment;
class CommentLikedNotification extends \Notification
{
/**
* Generate a message for a single notification
*
* @param Notification $notification
* @return string
*/
public function messageForNotification(Notification $notification) : string
{
return $this->sender->getName() . 'has liked your comment: ' . substr($this->reference->text, 0, 10) . '...';
}
/**
* Generate a message for a multiple notifications
*
* @param array $notifications
* @return string
*/
public function messageForNotifications(array $notifications, int $realCount = 0) : string
{
if ($realCount === 0) {
$realCount = count($notifications);
}
// when there are two
if ($realCount === 2) {
$names = $this->messageForTwoNotifications($notifications);
}
// less than five
elseif ($realCount < 5) {
$names = $this->messageForManyNotifications($notifications);
}
// to many
else {
$names = $this->messageForManyManyNotifications($notifications, $realCount);
}
return $names . ' liked your comment: ' . substr($this->reference->text, 0, 10) . '...';
}
/**
* Generate a message for two notifications
*
* John and Jane has liked your comment.
*
* @param array $notifications
* @return string
*/
protected function messageForTwoNotifications(array $notifications) : string
{
list($first, $second) = $notifications;
return $first->getName() . ' and ' . $second->getName(); // John and Jane
}
/**
* Generate a message many notifications
*
* Jane, Johnny, James and Jenny has liked your comment.
*
* @param array $notifications
* @return string
*/
protected function messageForManyNotifications(array $notifications) : string
{
$last = array_pop($notifications);
foreach($notifications as $notification) {
$names .= $notification->getName() . ', ';
}
return substr($names, 0, -2) . ' and ' . $last->getName(); // Jane, Johnny, James and Jenny
}
/**
* Generate a message for many many notifications
*
* Jonny, James and 12 other have liked your comment.
*
* @param array $notifications
* @return string
*/
protected function messageForManyManyNotifications(array $notifications, int $realCount) : string
{
list($first, $second) = array_slice($notifications, 0, 2);
return $first->getName() . ', ' . $second->getName() . ' and ' . $realCount . ' others'; // Jonny, James and 12 other
}
}
要在应用程序中处理通知,请创建类似通知管理器的内容:
class NotificationManager
{
protected $notificationAdapter;
public function add(Notification $notification);
public function markRead(array $notifications);
public function get(User $user, $limit = 20, $offset = 0) : array;
}
notificationAdapter在此示例mysql的情况下,该属性应包含与数据后端直接通信的逻辑.
使用mysql触发器没有错,因为没有错误的解决方案.什么有效,有效..但我强烈建议不要让数据库处理应用程序逻辑.
因此,在通知管理器中,您可能希望执行以下操作:
public function add(Notification $notification)
{
// only save the notification if no possible duplicate is found.
if (!$this->notificationAdapter->isDoublicate($notification))
{
$this->notificationAdapter->add([
'recipient_id' => $notification->recipient->getId(),
'sender_id' => $notification->sender->getId()
'unread' => 1,
'type' => $notification->type,
'parameters' => $notification->parameters,
'reference_id' => $notification->reference->getId(),
'created_at' => time(),
]);
}
}
该add方法的后面notificationAdapter可以是一个原始的mysql插入命令.使用此适配器抽象使您可以轻松地从mysql切换到基于文档的数据库,如mongodb,这对于Notification系统是有意义的.
在isDoublicate对方法notificationAdapter应该简单地检查是否已经存在具有相同的通知recipient,sender,type和reference.
我不能指出这只是一个例子.(另外我真的要缩短这篇文章后续步骤变得荒谬可笑--.-)
所以假设你有一种控制器在教师上传作业时采取行动:
function uploadHomeworkAction(Request $request)
{
// handle the homework and have it stored in the var $homework.
// how you handle your services is up to you...
$notificationManager = new NotificationManager;
foreach($homework->teacher->students as $student)
{
$notification = new Notification\Homework\HomeworkUploadedNotification;
$notification->sender = $homework->teacher;
$notification->recipient = $student;
$notification->reference = $homework;
// send the notification
$notificationManager->add($notification);
}
}
将在上传新作业时为每位教师的学生创建通知.
现在来了困难的部分.在PHP方面进行分组的问题是,您必须加载当前用户的所有通知才能正确分组.这将是不好的,如果你只有少数用户它可能仍然没有问题,但这并不能使它好.
简单的解决方案是简单地限制所请求的通知数量,并仅对这些通知进行分组.当没有太多类似的通知(例如每20个3-4个)时,这将正常工作.但是,让我们说用户/学生的帖子大约有一百个喜欢,你只选择最后20个通知.然后,用户将只看到20个人喜欢他的帖子,这也是他唯一的通知.
"正确"的解决方案是将已经存在于数据库中的通知分组,并且每个通知组仅选择一些样本.比你只需要将真实计数注入你的通知消息.
您可能没有阅读下面的文字,所以让我继续阅读一个片段:
select *, count(*) as count from notifications
where recipient_id = 1
group by `type`, `reference_id`
order by created_at desc, unread desc
limit 20
现在,您知道给定用户应该使用哪些通知以及该组包含的通知数量.
而现在是糟糕的部分.我仍然无法找到一种更好的方法来为每个组选择有限数量的通知,而无需对每个组进行查询.这里的所有建议都非常受欢迎.
所以我做了类似的事情:
$notifcationGroups = [];
foreach($results as $notification)
{
$notifcationGroup = ['count' => $notification['count']];
// when the group only contains one item we don't
// have to select it's children
if ($notification['count'] == 1)
{
$notifcationGroup['items'] = [$notification];
}
else
{
// example with query builder
$notifcationGroup['items'] = $this->select('notifications')
->where('recipient_id', $recipient_id)
->andWehere('type', $notification['type'])
->andWhere('reference_id', $notification['reference_id'])
->limit(5);
}
$notifcationGroups[] = $notifcationGroup;
}
我现在将继续假设notificationAdapters get方法实现此分组并返回如下数组:
[
{
count: 12,
items: [Note1, Note2, Note3, Note4, Note5]
},
{
count: 1,
items: [Note1]
},
{
count: 3,
items: [Note1, Note2, Note3]
}
]
因为我们的群组中始终至少有一个通知,并且我们的排序更喜欢未读和新通知,所以我们可以使用第一个通知作为渲染样本.
因此,为了能够使用这些分组通知,我们需要一个新对象:
class NotificationGroup
{
protected $notifications;
protected $realCount;
public function __construct(array $notifications, int $count)
{
$this->notifications = $notifications;
$this->realCount = $count;
}
public function message()
{
return $this->notifications[0]->messageForNotifications($this->notifications, $this->realCount);
}
// forward all other calls to the first notification
public function __call($method, $arguments)
{
return call_user_func_array([$this->notifications[0], $method], $arguments);
}
}
最后我们可以将大部分内容放在一起.这就是NotificationManager可能的get函数的样子:
public function get(User $user, $limit = 20, $offset = 0) : array
{
$groups = [];
foreach($this->notificationAdapter->get($user->getId(), $limit, $offset) as $group)
{
$groups[] = new NotificationGroup($group['notifications'], $group['count']);
}
return $gorups;
}
最后在一个可能的控制器动作中:
public function viewNotificationsAction(Request $request)
{
$notificationManager = new NotificationManager;
foreach($notifications = $notificationManager->get($this->getUser()) as $group)
{
echo $group->unread . ' | ' . $group->message() . ' - ' . $group->createdAt() . "\n";
}
// mark them as read
$notificationManager->markRead($notifications);
}