One to many relationship in laravel extracting the latest timestamp - php

Question

I have a one to many relationships in the database, and I am trying to extract the latest. The table names are notification and alertFrequency, they have models for each. I want to write a query that will get me the latest time stamp associated to a specific website in the notifications table. The alertFequency table has only 2 columns namely notification_id and created_at. the following are my model notification modl
class Notification extends Model
{
protected $fillable = ['id','website_url','email','slack_channel','check_frequency','alert_frequency','speed_frequency','active'];
public function statuses(){
return $this->belongsToMany('App\Status')->withPivot('values')->withTimestamps();
}
public function alertFrequencies(){
return $this->hasMany('App\AlertFrequency');
}
// trail versions
public function alert(){
$items = AlertFrequency::select('alertFrequencies.created_at')//Any column you want to fetch
->join('notifications', 'notifications.id', '=', 'alertFrequencies.notification_id')
->orderBy('alertFrequencies.created_at','desc')
->first();
if($items == null){
return null;
}
return $items->created_at->toDateTimeString();
class AlertFrequency extends Model{
protected $table = 'alertFrequencies';
public function notification(){
return $this->belongsTo('App\Notification');
}
}
inside the notification model i wrote a function that is expected to extract the data(i.e the latest time stamp of a specific website in the notification table) more over the notification_id is a foreign key in the alertFrequency table. the alert function is as follows
public function alert(){
$alert_timestamp = AlertFrequency::with('notification')->select('created_at')->orderBy('created_at','desc')->first();
//$alert_timestamp=$alert_timestamp->created_at->toDateTimeString();
if($alert_timestamp==null){
return false;
}
return $alert_timestamp;
}
it is returnning created_at time stamp but not the latset related to a specific website. i would apperciate your help?
in the database i have two websites added one at 12:18 and the second ata 12:24..... sorry i dont know how i can post the database here.

Answer 1

Directly You can not apply orderBy() on relation you need to use join()
Just try this. Hope it helps
$alert_timestamp = AlertFrequency::select('alertFrequencies.created_at')//Any column you want to fetch
->join('notification', 'notification.notification_id', '=', 'alertFrequencies.notification_id')
->orderBy('alertFrequencies.created_at','desc')
->get();