猫鼬的预钩子：从数组中删除_id

Question

我有两个模式：技能专长：var mongoose = require("mongoose");var SkillSchema = new mongoose.Schema({    skill: { type: String },    tally: { type: Number, default: 0 },    associatedUsers: { type: Array },});module.exports = mongoose.model("Skills", SkillSchema);轮廓：var mongoose = require("mongoose");var passportLocalMongoose = require("passport-local-mongoose");var profileSchema = new mongoose.Schema({     username: String,    password: String,    skills: { type: Array }    });profileSchema.plugin(passportLocalMongoose);module.exports = mongoose.model("Profile", profileSchema);该Skills文档包含与各种users（Skills. Skills.associatedUsers）相关的技能：{    "_id" : ObjectId("5cab5c8788368eafb68b75a4"),    "skill" : "cooking",    "__v" : 0,    "associatedUsers" : [        ObjectId("5cab5c7d88368eafb68b75a0"),        ObjectId("5cab546a7fb2b3a71c0404fa")    ],    "tally" : 0}该Profile文档包含一系列技能：{    "_id" : ObjectId("5cab546a7fb2b3a71c0404fa"),    "skills" : [        "cooking", "cleaning"    ],    "__v" : 0,    "username" : "deleteMe"}我正在尝试在Profile架构中实现预挂钩，以便在删除用户时，也删除user._idin的任何实例Skills.associatedUsers。我尝试了以下操作，但实际上删除了该技能的整个条目：const Skills = require("./skills");profileSchema.pre('remove', async function(){    console.log("clearing user ID from skills model");    await Skills.remove({associatedUsers: { $in: this._id } });});module.exports = mongoose.model("Profile", profileSchema);我怎样才能pull在._id从待删除的用户associatedUsers的数组Skills文件？

Answer 1

您需要update使用$ pull运算符，并指定multi: true从profile集合中的所有文档中删除该值：

profileSchema.pre('remove', async function(){

    console.log("clearing user ID from skills model");

    await Skills.update({}, { $pull: { associatedUsers: { $in: this._id } } }, { multi: true });

});