mongodb使用mongoose分組查詢

一個分組查詢的例子：model.aggregate([{$match: ops}, {$unwind: '$details'}, {$sort: {create_at: -1}}, {    $group: {        _id: {            promotion_id: "$promotion_id",            product_id: '$details.product_id',            need_pay: '$need_pay'        },        product_name: {$first:"$details.name"},        price: {$max: "$details.price"},        amount: {$sum: "$details.amount"},        packing: {$sum: "$details.packing"},        quantity: {$sum: "$details.quantity"}    }}, {$match: ops2}, {    $group: {        _id: {            promotion_id: "$_id.promotion_id",            need_pay: '$_id.need_pay'        },        details: {            $push: {                product_id: "$_id.product_id",                name: '$product_name',                price: '$price',                amount: '$amount',                packing: '$packing',                quantity: '$quantity'            }        }    }}], fn);