How can I optimise this eloquent query to remove similar queries - mysql

Question

An appointment can have many statuses, but the last created relation between appointment and status is the current status of the appointment. In my Appointment Datatable I want to display the related Agent, InstructionType, SignUpCustomer and the latest status. I want to paginate those records at 10 per page.
The relevant models are:
Appointment ( belongsTo agent, instruction_type and sign_up_customer, belongsToMany status)
Agent
InstructionType
SignUpCustomer
I have this query in my controller, which produces a result I send to Datatables.
$query = Appointment::with(['agent', 'instruction_type', 'sign_up_customer']);
$query->with(['statuses' => function ($query) {
$query->latest()->first();
}]);
$table = Datatables::of($query);
It is producing these two statements, the first one is fine, I don't need the last one. How can I optimise the query to remove that last statement?
select `statuses`.*, `appointment_status`.`appointment_id` as `pivot_appointment_id`, `appointment_status`.`status_id` as `pivot_status_id`, `appointment_status`.`created_at` as `pivot_created_at`, `appointment_status`.`updated_at` as `pivot_updated_at` from `statuses` inner join `appointment_status` on `statuses`.`id` = `appointment_status`.`status_id` where `appointment_status`.`appointment_id` in ('2') order by `created_at` desc limit 1
select `statuses`.*, `appointment_status`.`appointment_id` as `pivot_appointment_id`, `appointment_status`.`status_id` as `pivot_status_id`, `appointment_status`.`created_at` as `pivot_created_at`, `appointment_status`.`updated_at` as `pivot_updated_at`, `appointment_status`.`appointment_id` as `pivot_appointment_id`, `appointment_status`.`status_id` as `pivot_status_id`, `appointment_status`.`created_at` as `pivot_created_at`, `appointment_status`.`updated_at` as `pivot_updated_at` from `statuses` inner join `appointment_status` on `statuses`.`id` = `appointment_status`.`status_id` where `appointment_status`.`appointment_id` in ('2') order by `created_at` desc limit 1
I've also tried this:
Model:
/**
* #return \Illuminate\Database\Eloquent\Relations\BelongsToMany
*/
public function statuses()
{
return $this->belongsToMany(Status::class, 'appointment_status')->withTimestamps();
}
public function latestStatus()
{
return $this->statuses()->latest()->first();
}
Controller:
$query = Appointment::with(['agent', 'instruction_type', 'sign_up_customer', 'latestStatus']);
$table = Datatables::of($query);
But i get this error: BadMethodCallException in Builder.php line 2445:
Call to undefined method Illuminate\Database\Query\Builder::addEagerConstraints()

Answer 1

Can you not do this using a local scope? https://laravel.com/docs/5.4/eloquent#local-scopes
public function scopeLatest($query)
{
return $query->orderBy('created_at', 'DESC')->offset(0)->limit(1);
}
I've not actually done this before, but I see no reason why it wouldn't work (I also have no idea how optimised the resulting query would be).