复杂的 MongoDB 连接查询

Question

我想获取特定用户正在关注他们的用户的食谱

当 target_user_id in following schema 等于 user_id in recipe schema

遵循架构

user_id:{type:mongoose.ObjectId, require:true},
target_user_id:{type:mongoose.ObjectId, require:true}

配方架构

user_id:{type:mongoose.Schema.ObjectId, require:true},
username:{type: String, require: true},
type: { type: String, require: true },
title: { type: String, require: true },
description: { type: String, require: false },
ingredients: { type: Array, require: true },
directions: { type: Array, require: true },
cook_note: { type: String, require: false },
reviews_score: { type: Array, require: false, default:[0,0,0,0,0]}

Answer 1

已解决

const {_id:user_id} = req.user    
const recipes = await recipe_model.aggregate([
                { $lookup:{
                    from:'follows',
                    localField: "user_id",
                    foreignField: "target_user_id",
                    as: "followers"
                }},
                { $match : {followers: {$elemMatch:{ user_id: { $eq: user_id } } }}}
            ])