Bug: Hook function cannot access request-context variables

[iamdeit]

I have been working on adding an extra field (updatedBy) to every model by using a pre-findOneAndUpdate hook. The value I'm trying to assign is coming from a request-context object, where you can save global variables per request. The problem is that if I try to access the global variables via request-context object, it says undefined, and this only happens inside the pre hook for findOneAndUpdate.

I have tried to use https://www.npmjs.com/package/express-http-context and also https://www.npmjs.com/package/request-context but none of them seem to work. The weirdes part is that they work in the pre save hook.

For example:

const httpContext = require('express-http-context');

schema.pre('save', function () {
  const email = httpContext.get('email');
  console.log(email); // Prints the correct value!
  this.updatedBy = email; 
}


schema.pre('findOneAndUpdate', function () {
  const email = httpContext.get('email');
  console.log(email); // Prints undefined 
}

I also tried with post hooks but didn't work.

I'm using Mongo v3 and mongoose v5.1.5

[vkarpov15]

Thanks for reporting, we will look into this asap

[vkarpov15]

The below script seems to work fine for me in Mongoose 5.1.5 and 5.3.1, with [email protected], [email protected]. Can you try modifying the below script to demonstrate your issue?

const assert = require('assert');
const mongoose = require('mongoose');
mongoose.set('debug', true);

const httpContext = require('express-http-context');
const superagent = require('superagent');
const express = require('express');

const GITHUB_ISSUE = `gh7001`;
const connectionString = `mongodb://localhost:27017/${ GITHUB_ISSUE }`;
const { Schema } = mongoose;

run().then(() => console.log('done')).catch(error => console.error(error.stack));

async function run() {
  await mongoose.connect(connectionString);
  await mongoose.connection.dropDatabase();

  const app = express();

  app.use(httpContext.middleware);

  const userSchema = new Schema({ name: String });
  
  userSchema.pre('findOneAndUpdate', function(next) {
    console.log(httpContext.get('test'));
    next();
  });

  const User = mongoose.model('User', userSchema);

  app.get('/', function(req, res) {
    httpContext.set('test', '42');
    User.findOneAndUpdate({}, { name: 'Test' }, function() {
      res.json({ ok: 1 });
    });
  });

  await app.listen(3003);

  await superagent.get('http://localhost:3003/');

  console.log('done');
  process.exit(0);
}

[mtbnunu]

I was able to modify your script to reproduce the error, It showed up as I changed callback approach to async/await

const mongoose = require("mongoose");
mongoose.set("debug", true);

const httpContext = require("express-http-context");
const superagent = require("superagent");
const express = require("express");

const GITHUB_ISSUE = `gh7001`;
const connectionString = `mongodb://localhost:27017/${GITHUB_ISSUE}`;
const { Schema } = mongoose;

run()
	.then(() => console.log("done"))
	.catch(error => console.error(error.stack));

async function run() {
	await mongoose.connect(connectionString);
	await mongoose.connection.dropDatabase();

	const app = express();

	app.use(httpContext.middleware);

	const userSchema = new Schema({ name: String });

	userSchema.pre("find", function(next) {
		console.log(httpContext.get("test"));
		next();
	});

	const User = mongoose.model("User", userSchema);

	app.get("/", async (req, res) => {
		httpContext.set("test", "42");
		const user = await User.find({});
		res.json({ ok: 1 });
	});

	await app.listen(3003);

	await superagent.get("http://localhost:3003/");

	console.log("done");
	process.exit(0);
}