Express + Mongoose + 聚合 + 计算可用库存

Posted 2023-03-11

【中文标题】Express + Mongoose + 聚合 + 计算可用库存

【英文标题】：Express + Mongoose + Aggregation + Calculate Available Stock

【发布时间】：2021-08-05 09:31:48

【问题描述】：

我正在使用 express js 和 mongoose，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：按运动类型（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',
    itemsizeId: '609578ca23033e55886e7590',
    itemId: '609578ca23033e55886e758e',
    sizeId: '60950c0ba4982390f8dfed79',
    movementdate: '2021-05-15T11:34:35.118Z',
    movementtype: 'inward',
    movementcategory: 'purchase',
    quantity: 20,
    id: '609fb1cba7ed990f30d6cae3',
  ,
  
    _id: '609fb1fda7ed990f30d6cae4',
    refId: 'Sale-1',
    itemsizeId: '609578ca23033e55886e7590',
    itemId: '609578ca23033e55886e758e',
    sizeId: '60950c0ba4982390f8dfed79',
    movementdate: '2021-05-15T11:35:25.068Z',
    movementtype: 'outward',
    movementcategory: 'sales',
    quantity: 5,
    id: '609fb1fda7ed990f30d6cae4',
  ,
  
    _id: '609fb255a7ed990f30d6cae5',
    refId: 'Purchase-3',
    itemsizeId: '609578ca23033e55886e758f',
    itemId: '609578ca23033e55886e758e',
    sizeId: '60950be9a4982390f8dfed78',
    movementdate: '2021-05-15T11:36:53.835Z',
    movementtype: 'inward',
    movementcategory: 'purchase',
    quantity: 500,
    id: '609fb255a7ed990f30d6cae5',
  ,
  
    _id: '609fb27ea7ed990f30d6cae6',
    refId: 'Sale-2',
    itemsizeId: '609578ca23033e55886e758f',
    itemId: '609578ca23033e55886e758e',
    sizeId: '60950be9a4982390f8dfed78',
    movementdate: '2021-05-15T11:37:34.066Z',
    movementtype: 'outward',
    movementcategory: 'sales',
    quantity: 8,
    id: '609fb27ea7ed990f30d6cae6',
  ,
]

我已经尝试了下面的代码，我很高兴完成它：

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

【参考方案1】：

$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"] , "$quantity", 0] 
      
    
  ,
  
    $project: 
      quantity: 
        $subtract: ["$inward", "$outward"]
      
    
  
])

Playground

---

如果您在movementtype 中没有第三个类型，您也可以使用第二个公式，

$groupitemsizeId 检查条件如果movementtype 是inward 然后求和quantity 否则求和为负quantity

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

Playground