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/******************************************

The Base Model

******************************************/
<?php

namespace App;

use Illuminate\Support\Facades\DB;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Query\Builder;

class BaseModel extends Model {

/**
     * query scope nPerGroup
     *
     * @return void
     */
    public function scopeNPerGroup($query, $group, $n = 10)
    {
        // queried table
        $table = ($this->getTable());

// initialize MySQL variables inline
        $query->from( DB::raw("(SELECT @rank:=0, @group:=0) as vars, {$table}") );

// if no columns already selected, let's select *
        if ( ! $query->getQuery()->columns)
        {
            $query->select("{$table}.*");
        }

// make sure column aliases are unique
        $groupAlias = 'group_'.md5(time());
        $rankAlias  = 'rank_'.md5(time());

// apply mysql variables
        $query->addSelect(DB::raw(
            "@rank := IF(@group = {$group}, @rank+1, 1) as {$rankAlias}, @group := {$group} as {$groupAlias}"
        ));

// make sure first order clause is the group order
        $query->getQuery()->orders = (array) $query->getQuery()->orders;
        array_unshift($query->getQuery()->orders, ['column' => $group, 'direction' => 'asc']);

// prepare subquery
        $subQuery = $query->toSql();

// prepare new main base Query\Builder
        $newBase = $this->newQuery()
            ->from(DB::raw("({$subQuery}) as {$table}"))
            ->mergeBindings($query->getQuery())
            ->where($rankAlias, '<=', $n)
            ->getQuery();

// replace underlying builder to get rid of previous clauses
        $query->setQuery($newBase);
    }

}

/***********************************************************

The Board Model extending it

***********************************************************/
<?php

namespace App;

use App\BaseModel;

class Board extends BaseModel
{

public function pins()
    {
        return $this->hasMany('App\Pin');
    }

public function recentPins()
    {
        return $this->pins()->latest()->nPerGroup('board_id', 5);
    }
}

/***********************************************************

Calling the method in Tinker

***********************************************************/

App\Board::with('latestComments')->get();