聚合查询上的Mongodb填充字段
我有这三个系列(产品、用户和评论) 1。产品型号聚合查询上的Mongodb填充字段,mongodb,mongoose,nosql,aggregation-framework,Mongodb,Mongoose,Nosql,Aggregation Framework,我有这三个系列(产品、用户和评论) 1。产品型号 var ProductSchema = new Schema({ title: { type: String, text: true, required: true }, description: { type: String, required: true }, category: [{ type: String, required: true }], type: [{ t
var ProductSchema = new Schema({
title: { type: String, text: true, required: true },
description: { type: String, required: true },
category: [{ type: String, required: true }],
type: [{ type: String, required: true }],
isUsed: { type: Boolean, },
manufacturer: { type: String },
price: { type: Number },
});
var UserSchema = new Schema({
firstName: { type: String, text: true, required: true },
lastName: { type: String, text: true, required: true },
country: [{ type: String, required: true }],
phoneNumber: [{ type: String, required: true }]
});
var CommentSchema = new Schema({
comment: { type: String, text: true, required: true },
commented_by: { type: Schema.Types.ObjectId, ref: 'User', required: true },
commented_on: { type: Schema.Types.ObjectId, ref: 'Product', required: true }
});
2。用户模型
var ProductSchema = new Schema({
title: { type: String, text: true, required: true },
description: { type: String, required: true },
category: [{ type: String, required: true }],
type: [{ type: String, required: true }],
isUsed: { type: Boolean, },
manufacturer: { type: String },
price: { type: Number },
});
var UserSchema = new Schema({
firstName: { type: String, text: true, required: true },
lastName: { type: String, text: true, required: true },
country: [{ type: String, required: true }],
phoneNumber: [{ type: String, required: true }]
});
var CommentSchema = new Schema({
comment: { type: String, text: true, required: true },
commented_by: { type: Schema.Types.ObjectId, ref: 'User', required: true },
commented_on: { type: Schema.Types.ObjectId, ref: 'Product', required: true }
});
3。评论模式
var ProductSchema = new Schema({
title: { type: String, text: true, required: true },
description: { type: String, required: true },
category: [{ type: String, required: true }],
type: [{ type: String, required: true }],
isUsed: { type: Boolean, },
manufacturer: { type: String },
price: { type: Number },
});
var UserSchema = new Schema({
firstName: { type: String, text: true, required: true },
lastName: { type: String, text: true, required: true },
country: [{ type: String, required: true }],
phoneNumber: [{ type: String, required: true }]
});
var CommentSchema = new Schema({
comment: { type: String, text: true, required: true },
commented_by: { type: Schema.Types.ObjectId, ref: 'User', required: true },
commented_on: { type: Schema.Types.ObjectId, ref: 'Product', required: true }
});
然后,当发送请求以获取特定的产品时,这就是后台运行的mongoose代码
var aggregate = Product.aggregate([
{ "$match": { _id: ObjectId(req.params.id) } }, /** which is the product id **/
{ "$limit": 1 },
{
$lookup: {
from: 'comments',
let: { id: "$_id" },
pipeline: [
{ $match: { $expr: { $eq: [ "$commented_on.product", "$$id" ] } } },
],
as: "comments"
}
},
{
$addFields: {
comments: "$comments",
comments_no: { $size: "$comments" },
hasCommented: { $in: [ObjectId(req.user._id), "$comments.commented_by" ] }, /** req.user._id is the user's id **/
}
},
{
$project: {
_id: 1,
title: 1,
description: 1,
category: 1,
type: 1,
price: 1,
comments: 1,
hasCommented: 1,
comments_no: 1,
}
}
]);
输出
{
"_id": "5f992b5338f5f035f35911c5",
"title": "Some title here..."
"description": Some description here ...
"price": 1000,
"category": "Clothing",
"type": "shoe",
"comments": [
{
"comment": "Nice Product",
"commented_by": "5f992b5338f5f035f35911b2",
"commented_on": "5f992b5338f5f035f35911c5"
},
{
"comment": "I like this product",
"commented_by": "5f992b5338f5f035f35911a2",
"commented_on": "5f992b5338f5f035f35911c5"
},
{
"comment": "Great, I like it!",
"commented_by": "5f992b5338f5f035f35911c8",
"commented_on": "5f992b5338f5f035f35911c5"
}
],
"hasCommented": true,
"comments_no": 3
}
{
"_id": "5f992b5338f5f035f35911c5",
"title": "Some title here..."
"description": Some description here ...
"price": 1000,
"category": "Clothing",
"type": "shoe",
"comments": [
{
"comment": "Nice Product",
"commented_by": {
"_id": "5f992b5338f5f035f35911b2",
"firstName": "Jack",
"lastName": "Sparrow"
},
"commented_on": "5f992b5338f5f035f35911c5"
},
{
"comment": "I like this product",
"commented_by": {
"_id": "5f992b5338f5f035f35911a2",
"firstName": "John",
"lastName": "Doe"
},
"commented_on": "5f992b5338f5f035f35911c5"
},
{
"comment": "Great, I like it!",
"commented_by": {
"_id": "5f992b5338f5f035f35911c8",
"firstName": "Mary",
"lastName": "Jane"
},
"commented_on": "5f992b5338f5f035f35911c5"
}
],
"hasCommented": true,
"comments_no": 3
}
预期结果
{
"_id": "5f992b5338f5f035f35911c5",
"title": "Some title here..."
"description": Some description here ...
"price": 1000,
"category": "Clothing",
"type": "shoe",
"comments": [
{
"comment": "Nice Product",
"commented_by": "5f992b5338f5f035f35911b2",
"commented_on": "5f992b5338f5f035f35911c5"
},
{
"comment": "I like this product",
"commented_by": "5f992b5338f5f035f35911a2",
"commented_on": "5f992b5338f5f035f35911c5"
},
{
"comment": "Great, I like it!",
"commented_by": "5f992b5338f5f035f35911c8",
"commented_on": "5f992b5338f5f035f35911c5"
}
],
"hasCommented": true,
"comments_no": 3
}
{
"_id": "5f992b5338f5f035f35911c5",
"title": "Some title here..."
"description": Some description here ...
"price": 1000,
"category": "Clothing",
"type": "shoe",
"comments": [
{
"comment": "Nice Product",
"commented_by": {
"_id": "5f992b5338f5f035f35911b2",
"firstName": "Jack",
"lastName": "Sparrow"
},
"commented_on": "5f992b5338f5f035f35911c5"
},
{
"comment": "I like this product",
"commented_by": {
"_id": "5f992b5338f5f035f35911a2",
"firstName": "John",
"lastName": "Doe"
},
"commented_on": "5f992b5338f5f035f35911c5"
},
{
"comment": "Great, I like it!",
"commented_by": {
"_id": "5f992b5338f5f035f35911c8",
"firstName": "Mary",
"lastName": "Jane"
},
"commented_on": "5f992b5338f5f035f35911c5"
}
],
"hasCommented": true,
"comments_no": 3
}
当获得一个特定的产品时,我现在可以列出该产品的评论,但问题是在“评论人”部分列出的所有评论上,我需要用它填充它(需要名字、姓氏…)字段
你知道我该怎么做吗?你所做的是正确的。在
产品
和评论
之间进行查找后,您还需要进行另一次查找才能加入用户
您需要添加以下阶段以实现您的目标
将
展开到非结构化的
数组注释[]
加入查找
集合用户
- 由于lookup提供了一个数组,我们可以在安全操作符的帮助下使用
获取数组的第一个元素$arrayElemAt
。(如果$ifNull
为空,则脚本抛出错误。要处理此错误,我们使用注释[]
)$ifNull
- 我们已经解除了数组的结构,
帮助重新组合它group
{
$unwind: "$comments"
},
{
$lookup: {
from: "User",
let: {
id: "$comments.commented_by"
},
pipeline: [
{
$match: {
$expr: {
$eq: [
"$_id",
"$$id"
]
}
}
},
],
as: "comments.commented_by"
}
},
{
$addFields: {
"comments.commented_by": {
$ifNull: [
{
$arrayElemAt: [
"$comments.commented_by",
0
]
},
{}
]
}
}
},
{
$group: {
_id: "$_id",
title: {
$first: "$title"
},
hasCommented: {
$first: "$hasCommented"
},
comments: {
$push: "$comments"
}
}
}
工作
注意:仅供参考,变量和集合名称可能不同。这是否回答了您的问题:?