Using MongoDB with Mongoose — Pre Middleware Errors and Post Middlewares

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To make MongoDB database manipulation easy, we can use the Mongoose NPM package to make working with MongoDB databases easier.

In this article, we’ll look at how to use Mongoose to manipulate our MongoDB database.

Errors in Pre Hooks

We can raise errors in pre hooks in various ways.

For example, we can write:

async function run() {
  const { createConnection, Schema } = require('mongoose');
  const connection = createConnection('mongodb://localhost:27017/test');
  const schema  = new Schema({
    name: { type: String, required: true },
    age: Number
  });
  schema.pre('save', (next) => {
    const err = new Error('error');
    next(err);
  });
  const Kitten = connection.model('Kitten', kittenSchema);
}
run();

to pass an Error instance in the next method.

Also, we can return a promise:

async function run() {
  const { createConnection, Schema } = require('mongoose');
  const connection = createConnection('mongodb://localhost:27017/test');
  const kittenSchema = new Schema({
    name: { type: String, required: true },
    age: Number
  });
  schema.pre('save', (next) => {
    const err = new Error('error');
    return…