Sort the parent model based on the child model / relationship

Question

I have a model called appointments , each appointment has an option_id that is linked through a one to one relationship and the option_id can also be null . The option model has a property datetime_start . I want to sort the appointments based on the option.datetime_start .

Here is my code :

$appointments = $user->appointments()
->with(['option'
])
->get();

Edit :

Appointment model :

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Appointment extends Model
{
   /**
         * @return \Illuminate\Database\Eloquent\Relations\HasOne
   */
   public function option()
   {
     return $this->hasOne(Option::class, 'id', 'option_id');
   }
}

Option model :

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Option extends Model
{
    protected     $fillable = ["appointment_id",
                               "datetime_start"
    ];

    public function appointment()
    {
        return $this->belongsTo(Appointment::class, 'id','appointment_id');
    }
}

Any help would be greatly appreciated.

Answer 1

In order to sort Appointment model by a column from related Option model, you need to add a JOIN to your query so that you can sort by related fields:

$appointments = $user->appointments()
  ->leftJoin('options', 'options.appointment_id', '=', 'appointments.id')
  ->orderBy('options.datetime_start', 'ASC')
  ->with(['option'])
  ->get();

This will give you all appointments, including those without Option - the ones without an Option and, hence, without datetime_start , will be all returned either at the beginning or the end of the result list, you'll need to check that. If you only want appointments with Option , replace leftJoin() with join() .

Answer 2

$appointments = Appointment::with(['option' => function ($query){ $query->orderBy('datetime_start', 'desc'); } ])->get();