node.js - Mongoose Middleware pre 'remove' 不起作用，Model.update 不是函数

Question

我为 Book 架构设置了一个中间件查询:

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var User= require('./user');

var schema = new Schema({

    name : {type: String, required:true},
    startDate: {type: Date},// UTC datetime
    endDate: {type: Date},// UTC datetime
    status: {type: String},
    user: {type: Schema.Types.ObjectId, ref: 'User'}
});


schema.post('remove', function(next) {

    User.update(
        { books: this._id},
        { $pull: { books: this._id } })
        .exec();
    next();
});

module.exports = mongoose.model('Book', schema);

正如您所看到的，它尝试从用户的图书列表中删除该图书。有关引用，请参阅 User 架构(顺便说一句，此查询中的帖子查询有效):

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var Book = require('./book');

var schema = new Schema({

    firstName: {type: String, required: true},
    lastName: {type: String},
    phone1: {type: String},
    phone2: {type: String},
    email: {type: String},
    address: {type: Schema.Types.ObjectId, ref: 'Address'},
    books: [{type: Schema.Types.ObjectId, ref:'Book'}]
});

schema.post('remove', function (user) {
    Book.findById({$in : user.books}, function (err, book) {
        if (err) {
            return res.status(500).json({
                title: 'An error occurred cascade delete operations for user',
                error: err
            });
        }

        if (book) {
            book.user= undefined;
            book.save();
        }

    });
});
module.exports = mongoose.model('User', schema);

我不断收到此错误，我在查询中尝试了多种变体，但无济于事:

process.nextTick(function() { throw err; });
TypeError: User.update is not a function

有人可以帮我吗？

Answer 1

我认为你应该使用 .pre() 代替。希望这样的事情对你有用:

bookSchema.pre('remove', function (next) {
var book = this;
book.model('User').update(
    { books: book._id }, 
    { $pull: { books: book._id } }, 
    { multi: true }, 
    next);

});