How to sum of all values using hasManyRelation in laravel - laravel

Question

I am using laravel query builder. i got stuck somewhere. My query is like below :-
$details = File::query();
if($ftskey=="partially"){
$details = $details->with(['partialfiles'=>function($query) use($startdate,$enddate){
$query->whereDate('partial_date', '>=', $startdate)
->whereDate('partial_date', '<=', $enddate);
}]);
}
$details = $details->get();
$response = json_decode(json_encode($details),true);
//Relationship below
public function partialfiles(){
return $this->hasMany('App\PartialFile','file_id');
}
Output is coming below:-
Array
(
[0] => Array
(
[id] => 238
[file_no] => FSC334
[partialfiles] => Array
(
[0] => Array
(
[id] => 3
[file_id] => 238
[partial_date] => 2019-09-23
[partial_amount] => 50
)
[1] => Array
(
[id] => 4
[file_id] => 238
[partial_date] => 2019-09-23
[partial_amount] => 50
)
)
)
[0] => Array
(
[id] => 239
[file_no] => FSC335
[partialfiles] => Array
(
[0] => Array
(
[id] => 3
[file_id] => 238
[partial_date] => 2019-09-23
[partial_amount] => 100
)
[1] => Array
(
[id] => 4
[file_id] => 238
[partial_date] => 2019-09-23
[partial_amount] => 100
)
)
)
)
Now i want to add sum of all partial_amount key that i used in hasMany relationship i.e is 50+50+100+100 =300 my expected output is like below:-
Array
(
[0] => Array
(
[id] => 238
[file_no] => FSC334
[total_amount] => 300
[partialfiles] => Array
(
[0] => Array
(
[id] => 3
[file_id] => 238
[partial_date] => 2019-09-23
[partial_amount] => 50
)
[1] => Array
(
[id] => 4
[file_id] => 238
[partial_date] => 2019-09-23
[partial_amount] => 50
)
)
)
[0] => Array
(
[id] => 239
[file_no] => FSC335
[total_amount] => 300
[partialfiles] => Array
(
[0] => Array
(
[id] => 3
[file_id] => 238
[partial_date] => 2019-09-23
[partial_amount] => 100
)
[1] => Array
(
[id] => 4
[file_id] => 238
[partial_date] => 2019-09-23
[partial_amount] => 100
)
)
)
)
Now see i have added the key total_amount in array. Kindly help me how can i get the sum of all amount.
note :- Please don't suggest me foreach loop to do. As i want to do at query level only.

Answer 1

You can use sum() from Collection
$details->partialfiles()->sum('partial_amount');
also read this documentation from laravel: https://laravel.com/docs/5.8/collections