快递+猫鼬+聚合+计算可用库存

问题描述

我正在使用 express js 和 mongoose，而且我是这些平台的新手。如果有人可以帮助我，那就太好了。请参考以下数据，我正在寻找如下输出：

itemsizeId: 609578ca23033e55886e7590,AvailableQuantity: 112

itemsizeId: 609578ca23033e55886e758f,AvailableQuantity: 495

注意：按移动类型（向内/向外）分组。

可用库存：向内 - 向外

[
  {
    _id: '609fb1a1a7ed990f30d6cae2',refId: 'Purchase-1',itemsizeId: '609578ca23033e55886e7590',itemId: '609578ca23033e55886e758e',sizeId: '60950c0ba4982390f8dfed79',movementdate: '2021-05-15T11:33:52.894Z',movementtype: 'inward',movementcategory: 'purchase',quantity: 100,id: '609fb1a1a7ed990f30d6cae2',},{
    _id: '609fb1cba7ed990f30d6cae3',refId: 'Purchase-2',movementdate: '2021-05-15T11:34:35.118Z',quantity: 20,id: '609fb1cba7ed990f30d6cae3',{
    _id: '609fb1fda7ed990f30d6cae4',refId: 'Sale-1',movementdate: '2021-05-15T11:35:25.068Z',movementtype: 'outward',movementcategory: 'sales',quantity: 5,id: '609fb1fda7ed990f30d6cae4',{
    _id: '609fb255a7ed990f30d6cae5',refId: 'Purchase-3',itemsizeId: '609578ca23033e55886e758f',sizeId: '60950be9a4982390f8dfed78',movementdate: '2021-05-15T11:36:53.835Z',quantity: 500,id: '609fb255a7ed990f30d6cae5',{
    _id: '609fb27ea7ed990f30d6cae6',refId: 'Sale-2',movementdate: '2021-05-15T11:37:34.066Z',quantity: 8,id: '609fb27ea7ed990f30d6cae6',]

我一直尝试到下面的代码，我很高兴完成它：

const itemStock = await itemStockMovementModel.aggregate([
  {
    $match: { movementtype: 'inward' },{
    $group: {
      _id: {
        itemsizeId: '$itemsizeId',quantity: { $sum: '$quantity' },])

解决方法

• $group by itemsizeId 并按条件获取 inward 和 outward 的数量总和
• $subtract 到 inward - outward

const itemStock = await itemStockMovementModel.aggregate([
  {
    $group: {
      _id: "$itemsizeId",inward: {
        $sum: { $cond: [{ $eq: ["$movementtype","inward"] },"$quantity",0] }
      },outward: {
        $sum: { $cond: [{ $eq: ["$movementtype","outward"] },0] }
      }
    }
  },{
    $project: {
      quantity: {
        $subtract: ["$inward","$outward"]
      }
    }
  }
])

Playground

---

如果 movementtype 中没有第三种类型，您也可以使用第二个公式，

• $group by itemsizeId
• 如果 movementtype 为 inward，则检查条件，则求和 quantity 否则求和为负 quantity

const itemStock = await itemStockMovementModel.aggregate([
  {
    $group: {
      _id: "$itemsizeId",quantity: {
        $sum: {
          $cond: [
            { $eq: ["$movementtype",{ $subtract: [0,"$quantity"] }
          ]
        }
      }
    }
  }
])

Playground