Express Js + 猫鼬 + 加入

Question

我有两个 collection。尺寸和物品。 size在items中引用，查询items时需要加上size title

尺码collection

size:[{
_id: 123
title: S
},{
_id: 456
title:M
}]

项目collection

items:[{
title: item1,
    sizes:[{
     _id: object I'd
     sizeid: 123
     Price: 100
     },{
       _id: object I'd
       sizeid: 456,
       Price: 150
      }]
   }]

如何执行连接以获得低于输出

items:[{
title: item1,
    sizes:[{
     _id: object I'd
     sizeid: 123
     size: S ----> from size collection
     Price: 100
     },{
       _id: object I'd
       sizeid: 456,
       size: M -----;> from size collection
       Price: 150
      }]
   }]

Answer 1

您需要设计一个属性大小的 Items Schema 作为 ObjectID 数组，它将引用 Sizes Schema。

const ItemSchema = new Schema(
  {
    ...
    sizes: [{ type: Schema.Types.ObjectId, ref: 'Sizes' }]
  }
);

然后当你需要调整尺码的时候

const result = await Items.findOne(_id: itemId).populate('sizes');

Answer 2

我已经添加为虚拟字段。我是 MERN 堆栈的初学者。

itemSchema.virtual("sizemaster", {
  ref: "size",
  localField: "sizes.sizeId",
  foreignField: "_id",
});

itemSchema.virtual("itemsize").get(function (this: any) {
  const sizemaster = this.sizemaster;
  const itemsize = this.sizes.map(
    (s: {
      _id: any;
      sizeId: any;
      purchaseprice: any;
      mrp: any;
      salesprice: any;
      availablequantity: any;
    }) => {
      const sizeIndex = sizemaster.findIndex(
        (sm: { _id: { equals: (arg0: any) => any } }) => sm._id.equals(s.sizeId)
      );
      if (sizeIndex !== -1) {
        let itemsize = {
          itemsizeId: s._id,
          sizeId: s.sizeId,
          sizeTitle: sizemaster[sizeIndex].title,
          mrp: s.mrp,
          salesprice: s.salesprice,
          availablequantity: s.availablequantity,
        };

        return itemsize;
      }
    }
  );
  return itemsize;
});

Express Js + 猫鼬 + 加入

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