我目前有一个产品架构，其中包含一个包含不同数量对象的属性数组。一个对象看起来像这样:

[{ property: 'Color', value: 'Black' }, { property: 'Length', value: '1 inch' }]

每个产品都有随机数量的属性。问题是我无法查找产品并使用其标识符获取其属性。

下面是产品架构。

const mongoose = require('mongoose');

let product = new mongoose.Schema({
    id: { type: mongoose.Schema.Types.ObjectId },
    created_at: { type: Date, default: new Date()},
    language: { type: String, required: true },
    category: { type: String },
    articlenumber: { type: String },
    name: { type: String },
    properties: { type: [{}] }
});

module.exports = product;

我的属性集合中还有一个带有标识符的属性模式。

const mongoose = require('mongoose');

let property = new mongoose.Schema({
    id: { type: mongoose.Schema.Types.ObjectId },
    categoryPropertyId: { type: String },
    language: { type: String },
    name: { type: String, unique: true }
});

module.exports = property;

{ id: ObjectID, categoryPropertyId: '317', language: 'US', name: 'Color' }

我想获取一个产品并根据其名称和语言加入并获取 categoryPropertyId。

Mongoose 可以吗？我可以使用 javascript 循环来完成，但更喜欢加入之类的东西。

我查看了 $lookup 和 populate，但我对 mongoose 不是很熟练。感谢您的帮助!

一个产品

{
    _id: 5b3f18d93098293c4ab0ca4a,
    created_at: ‘2018-07-06 09:22:45.377’,
    language: ‘US’,
    category: ‘Phones’,
    articlenumber: ‘6700’,
    name: ‘Sony Phone’
    properties: [
    {
        property: ‘Version’,
        helptext: ‘’,
        value: ’8.0’    
    },
    {
        property: ‘Operating System’,
        helptext: ‘’,
        value: ‘Android’
    }]
}

属性数据集

[
    {
        id: ‘5b3603a56a14e1072ba6f4ef’,
        categoryPropertyId: ’429’,
        language: ‘US’,
        name: ‘Android’
    },
    {
        id: ‘5b3603a56a14e1072ba6f4ef’,
        categoryPropertyId: ’977’,
        language: ‘US’,
        name: ‘Version’
    },
    {
        id: ‘5b3603a56a14e1072ba6f4ef’,
        categoryPropertyId: ’1033’,
        language: ‘US’,
        name: ‘Weight’
    }
]

预期输出

{
    _id: 5b3f18d93098293c4ab0ca4a,
    created_at: ‘2018-07-06 09:22:45.377’,
    language: ‘US’,
    category: ‘Phones’,
    articlenumber: ‘6700’,
    name: ‘Sony Phone’
    properties: [
        {
            property: ‘Version’,
            helptext: ‘’,
            value: ’8.0’,
            categoryPropertyId: ’977’
        },
        {
            property: ‘Operating System’,
            helptext: ‘’,
            value: ‘Android’,
            categoryPropertyId: ’429’
        }
    ]
}

最佳答案

您可以尝试以下聚合

基本上你需要先$unwind "properties" 数组与外国“名称”相匹配... let让你 将字段从根文档(产品)保留到内部文档(属性)，最后使用 $group 您可以将拆分后的“属性”再次回滚到“属性”数组。

如果你有 mongodb 版本 3.6

db.product.aggregate([
  { "$unwind": "$properties" },
  { "$lookup": {
    "from": Properties.collection.name,
    "let": { "property": "$properties.property" },
    "pipeline": [
      { "$match": { "$expr": { "$eq": [ "$name", "$$property" ] } } },
      { "$project": { "categoryPropertyId": 1 }}
    ],
    "as": "properties.prop"
  }},
  { "$unwind": "$properties.prop" },
  { "$addFields": { 
    "properties.categoryPropertyId": "$properties.prop.categoryPropertyId" 
  }},
  { "$project": { "properties.prop": 0 }},
  { "$group": {
    "_id": "$_id",
    "created_at": { "$first": "$created_at" },
    "language": { "$first": "$language" },
    "category": { "$first": "$category" },
    "articlenumber": { "$first": "$articlenumber" },
    "name": { "$first": "$name" },
    "properties": { "$push": "$properties" }
  }}
])

如果你的 mongodb 版本低于 3.6

db.product.aggregate([
  { "$unwind": "$properties" },
  { "$lookup": {
    "from": Properties.collection.name,
    "localField": "properties.property",
    "foreignField": "name",
    "as": "properties.prop"
  }},
  { "$unwind": "$properties.prop" },
  { "$addFields": { 
    "properties.categoryPropertyId": "$properties.prop.categoryPropertyId" 
  }},
  { "$project": { "properties.prop": 0 }},
  { "$group": {
    "_id": "$_id",
    "created_at": { "$first": "$created_at" },
    "language": { "$first": "$language" },
    "category": { "$first": "$category" },
    "articlenumber": { "$first": "$articlenumber" },
    "name": { "$first": "$name" },
    "properties": { "$push": "$properties" }
  }}
])

关于node.js - 基于名称的 MongoDB/Mongoose 连接，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51538456/