UnhandledPromiseRejectionWarning: ReferenceError: book is not defined - node.js

Question

I stuck with a problem, when I hit my route addBook then getting an error like book is not defined don't know where I am please try to fix my code. if you have any query on my code please let me know.
route.js
This is the route.js file where I wrote my all logics
const express = require("express");
const router = express.Router();
const Publisher = require('../model/Categary');
const Book = require('../model/Product');
// const {addCatogary} = require('../controllers/Product');
// router.get('/addcatogary',addCatogary);
router.post("/addPublisher", async (req, res) => {
try {
//validate req.body data before saving
const publisher = new Publisher(req.body);
await publisher.save();
res.status(201).json({ success: true, data: publisher });
console.log(publisher);
} catch (err) {
res.status(400).json({ success: false, message: err.message });
}
console.log(err);
});
router.post("/addBook", async (req, res) => {
try {
//validate data as required
const book = new Book(req.body);
// book.publisher = publisher._id; <=== Assign user id from signed in publisher to publisher key
await book.save();
const publisher = await Publisher.findById({ _id: book.publisher });
publisher.publishedBooks.push(book);
await publisher.save();
//return new book object, after saving it to Publisher
res.status(200).json({ success: true, data: book });
} catch (err) {
res.status(400).json({ success: false, message: err.message });
}
console.log(book);
});
router.get("/publishers", async (req, res) => {
try {
const data = await Publisher.find().populate({
path: "booksPublished",
select: "name publishYear author",
});
res.status(200).json({ success: true, data });
} catch (err) {
res.status(400).json({ success: false, message: err.message });
}
console.log(data)
});
module.exports = router;
Product.js
const mongoose= require('mongoose');
const {Schema} = require('mongoose');
const bookSchema = new Schema({
name: String,
publishYear: Number,
author: String,
publisher: {
type: Schema.Types.ObjectId,
ref: 'Publisher',
required: true
}
},
{timestamps: true});
module.exports = mongoose.model('Book', bookSchema);
Catogary.js
This is the Catogary model.
const mongoose = require('mongoose');
const {Schema} = require('mongoose');
const publisherSchema = new Schema({
name: String,
location: String
},
{timestamps: true}
);
publisherSchema.virtual('booksPublished', {
ref: 'Book', //The Model to use
localField: '_id', //Find in Model, where localField
foreignField: 'publisher', // is equal to foreignField
});
// Set Object and Json property to true. Default is set to false
publisherSchema.set('toObject', { virtuals: true });
publisherSchema.set('toJSON', { virtuals: true });
module.exports = mongoose.model('Publisher', publisherSchema);

Answer 1

router.post("/addBook", async (req, res) => {
try {
//validate data as required
const book = new Book(req.body);
// book.publisher = publisher._id; <=== Assign user id from signed in publisher to publisher key
await book.save();
const publisher = await Publisher.findById({ _id: book.publisher });
publisher.publishedBooks.push(book);
await publisher.save();
//return new book object, after saving it to Publisher
res.status(200).json({ success: true, data: book });
} catch (err) {
res.status(400).json({ success: false, message: err.message });
}
console.log(book);
});
hey brother!
you have written a nice code but you have made a small mistake after catch block you are logging book which is defined inside try block and that book variable can not be accessed outside of that box because its local variable and can be only used inside try block
if you wanted to used that variable outside of try{} catch(){} block defined it with var
just check below link
geeksforgeeks.org/global-and-local-variables-in-javascript
happy hacking :)