我如何从猫鼬模型中的另一个模型访问字段

Question

我在这里制作了两个MongoDB模型

电影模型

import mongoose from 'mongoose';
const movieSchema = new mongoose.Schema({
title: {
type: String,
required: [true, 'Please Enter the Movie Title'],
trim: true,
minlength: 5,
maxlength: 255
},
genre: {
type: mongoose.Schema.ObjectId,
ref: 'Genre',
required: true
},
year: {
type: Number,
min: 1800,
max: 3000,
required: [true, 'Please enter the year of the movie.']
},
directors: [
{
type: String,
minlength: 5,
maxlength: 100
}
],
writers: [
{
type: String,
minlength: 5,
maxlength: 100
}
],
cast: [
{
type: String,
minlength: 5,
maxlength: 100
}
],
numberInStock: {
type: Number,
required: true,
min: 0,
max: 255
},
dailyRentalRate: {
type: Number,
required: true,
min: 0,
max: 255
}
});
export default mongoose.model('Movie', movieSchema);

租赁模型

import mongoose from 'mongoose';
import moment from 'moment';
const rentalSchema = new mongoose.Schema({
customer: {
type: mongoose.Schema.ObjectId,
ref: 'Customer',
required: true
},
movie: {
type: mongoose.Schema.ObjectId,
ref: 'Movie',
required: true
},
dateOut: {
type: Date,
required: true,
default: Date.now
},
dateReturned: {
type: Date
},
rentalFee: {
type: Number,
min: 0
}
});

rentalSchema.methods.return = function () {
this.dateReturned = new Date();
this.rentalFee =
moment().diff(this.dateOut, 'days') * this.movie.dailyRentalRate;
};
export default mongoose.model('Rental', rentalSchema);

返回控制器

import catchAsync from '../utils/catchAsync.js';
import AppError from '../utils/appError.js';
import Rental from '../models/rentalModel.js';
import Movie from '../models/movieModel.js';
const returns = catchAsync(async (req, res, next) => {
const rental = await Rental.findOne({
customer: req.body.customerID,
movie: req.body.movieID
});
// console.log(rental);
if (!rental) {
return next(new AppError('Not Found', 400));
}
if (rental.dateReturned) {
return next(new AppError('Already Returned', 400));
}
rental.return();
await rental.save();
// add movie back into stock
await Movie.updateOne(
{ _id: rental.movie._id },
{
$inc: { numberInStock: 1 }
}
);
res.status(400).json({
status: 'success',
rental
});
});
export default returns;

返回路线

import { Router } from 'express';
import { protect } from '../controllers/authController.js';
import returns from '../controllers/returnController.js';
const router = Router();
router.post('/', protect, returns);
export default router;

问题是，当我想访问Rental Model中的电影字段时，它会返回电影ID但我希望它返回包含电影数据的对象(类似于填充，但在模型逻辑中(因此，如果我试图访问this.movie.daylyRentalRate，它会返回未定义的值

Answer 1

MongoDB具有$lookupaggregation运算符。Mongoose有一个名为populate()的替代方案，它允许您引用其他集合中的文档。填充是用其他集合中的文档自动替换文档中指定的路径的过程，因此您可以使用填充来解决您的问题，如下所示：

const rental = await Rental.findOne({
customer: req.body.customerID,
movie: req.body.movieID
}).populate("movie")

它对我很有效，在methods.return中，你可以访问this.movie.dailyRentalRate