Is there any Eloquent way to get sum of relational table and sort by it? - sql

Question

Example:
table Users
ID | Username | sex
1 | Tony | m
2 | Andy | m
3 | Lucy | f
table Scores
ID | user_id | score
1 | 2 | 4
2 | 1 | 3
3 | 1 | 4
4 | 2 | 3
5 | 1 | 1
6 | 3 | 3
7 | 3 | 2
8 | 2 | 3
Expected Result:
ID | Username | sex | score_sum (sum) (desc)
2 | Andy | m | 10
1 | Tony | m | 8
3 | Lucy | f | 5
The code I use so far:
User model:
class User extends Authenticatable
{
...
public function scores()
{
return $this->hasMany('App\Score');
}
...
}
Score model
class Job extends Model
{
//i put nothing here
}
Code in controller:
$users = User::all();
foreach ($users as $user){
$user->score_sum = $user->scores()->sum('score');
}
$users = collect($users)->sortByDesc('score_sum');
return view('homepage', [
'users' => $users->values()->all()
]);
Hope my example above make sense. My code does work, but I thought there must be an Eloquent and elegant way to do this without foreach?

Answer 1

There are 2 options for doing this in an Eloquent way.
Option 1
The first way is to do this to add the score_sum as an attribute that is always included when querying the users model. This is only a good idea if you will be using the score_sum the majority of the time when querying the users table. If you only need the score_sum on very specific view or for specific business logic then I would use the second option below.
To do this you will add the attribute to the users model, you can look here for documentation: https://laravel.com/docs/5.6/eloquent-mutators#defining-an-accessor
Here is an example for your use case:
/app/User.php
class User extends Model
{
.
.
.
public function getScoreSumAttribute($value)
{
return $this->scores()->sum('score');
}
}
Option 2
If you just want to do this for a single use case, then the easiest solution is just to use the sum() function in the eventual foreach loop you will be using (most likely in the view).
For example in a view:
#foreach($users as $user)
<div>Username: {{$user->username}}</div>
<div>Sex: {{$user->sex}}</div>
<div>Score Sum: {{$user->scores()->sum('price')}}</div>
#endforeach
Additionally, if you do not want to do this in a foreach loop you can use a raw query in the Eloquent call in your Controller gets the `score_sum'. Here is an example of how that can be done:
$users = User::select('score_sum',DB::raw(SUM(score) FROM 'scores'))->get();
I did not have a quick environment to test this, you might need a WHERE clause in the DB::raw query
Hope this helps!

Answer 2

This is as nice as it gets:
User::selectRaw('*, (SELECT SUM(score) FROM scores WHERE user_id = users.id) as score_sum')
->orderBy('score_sum', 'DESC')
->get();