Finding sum through eager loading - php

Question

I've a table schema as follows:
+----+---------------+------------+--------+
| id | crowd_fund_id | email | amount |
+----+---------------+------------+--------+
| 1 | 11 | jj#xx.com | 200 |
| 2 | 11 | sd#ff.com | 250 |
| 3 | 12 | jj#xx.com | 150 |
| 4 | 12 | abc#cc.com | 230 |
+----+---------------+------------+--------+
And a Entries table:
+----+---------+----------+------+
| id | user_id | crowd_id | name |
+----+---------+----------+------+
| 1 | 6 | 11 | Abc |
| 2 | 6 | 12 | Xyc |
| 3 | 8 | 18 | ijn |
+----+---------+----------+------+
In the Backer's Model
public function entry()
{
return $this->belongsTo('App\Entries', 'crowd_fund_id', 'crowd_id');
}
and in the Controller I've called:
$var = Backers::with('entry')->where('email', $user->email)->get();
This works fine. Now I wanted to get the sum also through the eager loading.
That means I need to call something like
Backers::with('entry')->with('sum')->where('email', $user->email)->get();
The sum will calculate the total of all the amount where crowd_fund_id is equal to the raw where email = $user->email.
That means when I call
Backers::with('entry')->with('sum')->where('email', $user->email)->get();
I should be getting :
1 raw for the backer's details with crowd_fund_id
1 raw for the corresponding entry where crowd_fund_id = crowd_id
1 sum of all amount where crowd_fund_id = crowd_fund_id from the backer's details.
How can I get this?

Answer 1

Could you try something along these lines (in your Backers model):
public function backersSum()
{
return $this->hasOne('App\Backer')
->selectRaw('crowd_fund_id, sum(amount) as aggregate')
->groupBy('crowd_fund_id');
}
Doing it this way allows you to eager load it like any relationship. Then you could do something like this to access it:
public function getBackersSumAttribute()
{
if ( ! $this->relationLoaded('backersSum'))
$this->load('backersSum');
$related = $this->getRelation('backersSum');
return ($related) ? (int) $related->aggregate : 0;
}