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modified version of https://gist.github.com/juavidn/80a8b5cc755330120b690a82469fbfe2
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<?php | |
namespace App\Traits; | |
use DB; | |
use Illuminate\Database\Eloquent\Builder; | |
use Illuminate\Database\Query\JoinClause; | |
use phpDocumentor\Reflection\Types\Mixed_; | |
trait LimitPerGroupable | |
{ | |
/** | |
* @param Builder $query | |
* @param int $limit | |
* @return mixed | |
*/ | |
public function scopeLimitPerGroup(Builder $query, $limit = 15) | |
{ | |
$judgement = !$query->getQuery()->wheres ?: $query->getQuery()->wheres[0]; | |
// check if query is actual eager load | |
if (!$judgement || | |
(!strpos($judgement['column'], '.') && !isset($judgement['values'])) | |
) { | |
$query->limit((int)$limit); | |
$query->getModel()->setPerPage((int)$limit); | |
return $query; | |
} | |
/** @var JoinClause $join */ | |
$join = $query->getQuery()->joins[0]; | |
$table = $this->getTable(); | |
$eagerLoadFullColumn = $judgement['column']; | |
$bindings = $query->getBindings(); | |
// make sure column aliases are unique | |
$numAlias = "{$table}_rn_" . uniqid(); | |
$groupAlias = "{$table}_grp_" . uniqid(); | |
/** @var Builder $newBaseQuery */ | |
$newBaseQuery = $this->newQueryWithoutScopes()->getQuery(); | |
$subQuery = clone $query; | |
$subQuery->select("{$table}.*"); | |
// initialize MySQL variables inline | |
$subQuery->from(DB::raw("(select @num:=0, @group:=0) as vars, {$table}")); | |
// apply mysql variables | |
$subQuery->selectRaw("@num := if(@group = {$eagerLoadFullColumn}, @num + 1, 1) AS {$numAlias}"); | |
$subQuery->selectRaw("@group := {$eagerLoadFullColumn} AS {$groupAlias}"); | |
// make sure first order clause is the group order | |
$subQuery->getQuery()->orders = (array)$subQuery->getQuery()->orders; | |
array_unshift($subQuery->getQuery()->orders, [ | |
'column' => $eagerLoadFullColumn, | |
'direction' => 'asc' | |
]); | |
// for many to many table relationship | |
if ($join) { | |
$subQuery->addSelect($eagerLoadFullColumn); | |
$newBaseQuery->joins = $subQuery->getQuery()->joins; | |
$eagerLoadColumn = explode('.', $eagerLoadFullColumn)[1]; | |
$inspectColumn = "{$table}.{$eagerLoadColumn}"; | |
$newBaseQuery->whereRaw("{$inspectColumn} = {$eagerLoadFullColumn}"); | |
} | |
$query->setQuery($newBaseQuery); | |
$query->from(DB::raw("({$subQuery->toSql()}) as {$table}")); | |
$query->setBindings($bindings); | |
$query->where($numAlias, '<=', (int)$limit); | |
} | |
} |
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