Laravel – Get sum of a column without querying to database more than once

My table structure is like this:

id      user_id     gift
1       1           1000

but now I want to move the gift to another table since the gift can be given to the users more than once in different dates. I have used $user->gift in many places in my project and I don’t want to change the code. So I want to create a method in User model called getGiftAttribute. Inside this method I’m going to have the sum of the gifts. But now the problem is that each time that $user->gift is called in my code it queries the database, but I want it to be called once. As previously if I used $user->gift, it would query only once. So how can I get the sum of gift which is in another table without querying more than once?

Answer

If you really don’t want to change your code at all and get the sum of gifts at multiple places with only one query, you could do something like this:

class User extends Models {
    protected $sumGifts = null;

// [...]

    public function getGiftAttribute()
    {
       if($this->sumGifts == null){
           $this->sumGift = $this->gifts()->sum('gift'); 
           // or whatever you use to retrieve the sum of all gifts
       }

       return $this->sumGifts;
    }
}

Doing so, you are storing the sum of all gifts inside a property of your User model and therefore the query will be executed only once, when you first use $user->gift. All subsequent calls to $user->gift will return the sum previously stored in the sumGifts property.

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It will work, however, I think a better approach would be to wisely use relationships and eagerloading.