models/index.js doesn't work with ES6 modules

[ngustavo]

What you are doing?

Trying to load models with models/index.js doesn't work with ES6 modules activated with "type": "module"

const basename = path.basename(__filename);
// {...}
const model = require(path.join(__dirname, file))(sequelize, Sequelize.DataTypes);

Variables like __filename and __dirname don't work anymore with modules.

What do you expect to happen?

There should be an option to choose between Modules or CommonJS.

What is actually happening?

There's only CommonJS support.

[Kulwch]

Hi,
Having the same problem. Tried a long list of things to fix the problem, can't solve it. I'm stuck in a project i'm supposed to deliver in 2 weeks... Is there any chance someone has an idea of what to do? I searched for hours on the web, didn't find a useful thing.

[ngustavo]

For now, I created this temporary solution.

[Kulwch]

As a matter of fact, i occured this error since i didn't delete a model i created manually before using sequelize-cli... Thanks anyway for your answer, i'll keep it in mind !

[NixonAzeredo]

This is my solution for the moment

import { readdirSync } from "fs";
import { basename, dirname } from "path";
import { Sequelize, DataTypes } from "sequelize";
import { fileURLToPath } from 'url';
import database from "../config/database.js";

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

const db = {};
const sequelize = new Sequelize(database.development);

export default (async () => {
  const files = readdirSync(__dirname)
    .filter(
      (file) => file.indexOf('.') !== 0
      && file !== basename(__filename)
      && file.slice(-3) === '.js',
    );

  for await (const file of files) {
    const model = await import(`./${file}`);
    const namedModel = model.default(sequelize, DataTypes);
    db[namedModel.name] = namedModel;
  }

  Object.keys(db).forEach((modelName) => {
    if (db[modelName].associate) {
      db[modelName].associate(db);
    }
  });

  db.sequelize = sequelize;
  db.Sequelize = Sequelize;
	
  return db;
})();

[WikiRik]

@ephys can you look into this?

[ephys]

I'm not sure how to go about fixing this.

If we generate CJS code, it's not going to work for users that use ESM.
If we generate ESM, it's not going to work for users that use CJS.

I suppose we could prompt during generation which module system to use

[ngustavo]

I guess it's possible to use *.mjs, since it's a standard, just to differentiate. Then, at generation time, only copy those with the corresponding extension.
There's also the package.json option, "type": "module". This would imply having premade packages, as CRA does.
The last option is doing weird string interpolation.

[ephys]

If we were to generate .mjs, users using commonjs would not be able to require those files
But I think we could just maintain both a mjs & cjs version and prompt the user to choose one (with the default being guessed from package.json)

[ngustavo]

That's what I meant by "differentiate" and "corresponding extension". It's the easiest way to go.
I'm not sure if Node can figure it out on its own though when given duplicate files.

[ephys]

Well import requires specifying the file extension and require is unable to load esm so it should, but it would be cleaner to emit only one of them by asking the user the choose
It shouldn't be a difficult to implement but I'm mostly focused on the main library right now - if someone wants to give a shot at a PR

(The CLI code is also in dire need of an update and I'd like to migrate it to ESM before doing anything else too)

[mirzagirl]

model.default ......error saying TypeError: model.default is not a function please help