问题描述
我想计算利润,我需要获取项目 JsonArray,它是其他嵌套 JsonArray 订单的一部分
var mapProfit=function(){for(var i in this.order)emit(this.order[i],1)}
var redProfit=function(k,v){return Array.sum(v)}
db.OnlineGrocery.mapReduce(mapProfit,redProfit,{out:"Result"}).find()
{
"_id" : ObjectId("605ac4dcf77f914c2aab81b0"),"customer_id" : NumberInt(1),"customer_firstName" : "Lannie","customer_lastName" : "Chazerand","customer_email" : "lchazerand0@usnews.com","customer_phoneNumber" : "3862602788","address" : [
{
"street" : "00523 Helena Plaza","city" : "Cincinnati","province" : "Ohio"
}
],"order" : [
{
"order_id" : "98-037-3943","order_date" : "6/22/2020","item" : [
{
"item_id" : NumberInt(1),"item_name" : "Appetizer - Mango Chevre","item_desc" : "Nondisp fx of pisiform,unsp wrist,init for clos fx","item_qty" : NumberInt(5),"item_actual_price" : "$2.78","item_selling_price" : "$8.23"
},{
"item_id" : NumberInt(2),"item_name" : "Pork - Bacon,back Peameal","item_desc" : "Other cervical disc disorders at C6-C7 level","item_qty" : NumberInt(2),"item_actual_price" : "$1.53","item_selling_price" : "$6.71"
}
]
}]
}
解决方法
您可以使用点或括号表示法访问 JSON 对象,但由于 order 属性包含一个对象数组,因此您必须先访问数组索引,然后才能访问数组内的对象属性。在这种情况下,它看起来像 order[index0].item[selectedItemIndex].item_qty/anyOtherItemProperty
希望这会有所帮助,否则请提供有关您的问题的更多详细信息。
,MapReduce 可能不是您计算利润所需的工具。
为了获得整体利润,您可以简单地将订单和商品平仓,然后总结一下:
db.collection.aggregate([
{$unwind: "$order"},{$unwind: "$order.item"},{$group: {
_id: null,profit: {
$sum: {
$subtract: [
{$toDecimal: {
$trim: {
chars: {$literal: "$"},input: "$order.item.item_selling_price",}
}},{$toDecimal: {
$ltrim: {
input: "$order.item.item_actual_price",chars: {$literal: "$"}
}
}}
]
}
}
}}
])
或者,如果您需要每件商品或每笔订单的利润,则需要几个小组阶段:
db.collection.aggregate([
{$unwind: "$order"},{$addFields: {
"order.item.profit": {
$subtract: [
{$toDecimal: {
$trim: {
chars: {$literal: "$"},{$toDecimal: {
$ltrim: {
input: "$order.item.item_actual_price",chars: {$literal: "$"}
}
}}
]
}
}},{$group: {
_id: {
_id: "$_id",order: "$order.order_id"
},root: {$first: "$$ROOT"},items: {$push: "$order.item"},profit: {$sum: "$order.item.profit"}
}},{$addFields: {
"root.order.item": "$items","root.order.profit": "$profit"
}},{$replaceRoot: {newRoot: "$root"}},{$group: {
_id: "$_id",orders: {$push: "$order"}
}},{$addFields: {"root.order": "$orders"}},{$replaceRoot: {newRoot: "$root"}}
])