我想为Transactions集合创建meteorreact聚合。交易有日期，所以我想按月汇总数据。代码是:ReactiveAggregate(this,Transactions,[{$match:{'date':{$gte:newDate(startDate),$lt:newDate(endDate)}}},{'$group':{'_id':{month:{$month:"$date"}},'totalProfit':{$sum:"$totalProfit"},'totalSales':{$sum:"$totalSales"},'totalExpenses':{$sum:"$tota