ERR_REQUIRE_ESM error when importing module in Nestjs project

[rvalle]

I am getting into trouble just trying to use geolite2-redist from nestjs

I am not completely sure who is at fault if the module metadata or nestjs compilation process.

Since nestjs is a very widespread nodejs appolication framework I deceded to notify it here.

Looks like nestjs is assuming this library is CJS but it looks ESM to me. I would assume that something in project.json is triggering this situation.

Any idea why this is happening?

It can be reproduced by creating an empty NestJS project and using geolite2-redist from the controller or service.

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: .../node_modules/geolite2-redist/dist/index.js
require() of ES modules is not supported.
require() of .../node_modules/geolite2-redist/dist/index.js from .../dist/geolite.service.js is an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which defines all .js files in that package scope as ES modules.
Instead rename index.js to end in .cjs, change the requiring code to use import(), or remove "type": "module" from .../node_modules/geolite2-redist/package.json.

[GitSquared]

You'll find helpful information here on how to use modern ESM packages

[rvalle]

As a module user, I think I am using it correctly:

import geolite2, {GeoIpDbName} from 'geolite2-redist';
import maxmind from 'maxmind';

from my typescript service.

[rvalle]

I am also using other ESM modules (all nestjs distribution), but those look similar to geolite2-redist....

so, I am not sure what exactly is causing the trouble.

[rvalle]

the issue can easily be reproduced by creating a new nestjs project, and replacing the controller with this code, which would inject the databases as a dependency into the controller after they have been downloaded:

import { Controller, Get } from '@nestjs/common';
import { Inject, Injectable, Logger } from '@nestjs/common';

import { AppService } from './app.service';

import geolite2, { GeoIpDbName } from 'geolite2-redist';
import maxmind from 'maxmind';

@Controller()
export class AppController {
  constructor(
    private readonly appService: AppService,
    @Inject('GEOLITE_DB') private readonly geolite,
  ) {
    // nothing
  }

  @Get()
  getHello(): string {
    return this.appService.getHello();
  }
}

export const GeoliteDBService = {
  provide: 'GEOLITE_DB',
  useFactory: async () => {
    const logger = new Logger('GEOLITE_DB');
    await geolite2.downloadDbs();
    logger.log('Geolite2 Databases Downloaded');
    return {
      asn: await geolite2.open(GeoIpDbName.ASN, (path) => maxmind.open(path)),
      country: await geolite2.open(GeoIpDbName.Country, (path) =>
        maxmind.open(path),
      ),
    };
  },
};

[rvalle]

this seems to be related https://github.com/nestjs/nest/issues/7021

[rvalle]

this is very strange.... anyway, the only workaround I can find is to downgrade to version 2.x

[GitSquared]

Hmm, indeed, your usage is correct.

I'm not familiar with Nest.js, but this comment in the issue you linked seems to indicate that you could work around the issue by adding a bundler like Rollup to your build step?

Also, are you using node 12 or later?

[rvalle]

I am testing against node 14 and 16, both display the issue.

I think, generally speaking, this issue is related to the "transition" to ESM, everybody seems to be taking steps towards it, but steps may be conflicting.

I am not familiar with Rollup, but I will certainly review it.

[notimobi]

I have the same issue with 3.0. I tried the sample code from the README, using both nodejs 14 and16. All result in the same error. The only solution to me is to downgrade to 2.0. I have not found a workaround yet.

[GitSquared]

@notimobi have you looked here? Are you using nestjs as well?

[notimobi]

I think I found the cause of the issue. When using nvm, this issue arises. After bypassing the nvm command, the code works fine. Thanks @GitSquared

[rvalle]

This seems to be an issue on NestJS, for not having direct support of ESM modules. I found it easier just to use the 2.0 for now. I guess the other alternative is to use bundling. It not intuitive to be writing ESM modules and not been able to use them, at the same time.

[GitSquared]

Closing as there's nothing I can do here, but feel free to link an issue on Nest's side if they start working on this...