Illuminate\Database\Eloquent\Model::resolveConnection PHP Method

    public static function resolveConnection($connection = null)
    {
        return static::$resolver->connection($connection);
    }

 /**
  *
  */
 private function addSelect()
 {
     $rawSelect = [];
     foreach ($this->columns as $index => $column) {
         if (isset($this->rawColumns[$index])) {
             $rawSelect[] = $this->rawColumns[$index] . ' as ' . Model::resolveConnection()->getQueryGrammar()->wrap($this->columnNames[$index]);
         }
     }
     $this->builder = $this->builder->select(new raw(implode(', ', $rawSelect)));
 }