Error: Loki cannot be used as a constructor

Question

Error: Loki cannot be used as a constructor

Can anyone assist me in understanding why this code is not functioning correctly?

Here's what my index.ts file in Hapi.js looks like:

import { Server, Request, ResponseToolkit } from '@hapi/hapi';
import * as Loki from 'lokijs';

...

const db = new Loki(`${UPLOAD_PATH}/${DB_NAME}`, { persistenceMethod: 'fs' });

This code snippet is pretty straightforward and has been adapted from a well-known example

The scripts section in my package.json appears as follows:

"scripts": {
"prestart": "tsc",
"start": "node dist/index.js",
...

These scripts compile into dist/index.js. However, upon running the 'start' command, I encounter the following error:

TypeError: Loki is not a constructor

I have tried various solutions but seem to be missing the key point. I would greatly appreciate any assistance on how to properly instantiate a new Loki() object and why it works differently elsewhere.

Thank you for your support!

node.js typescript import hapi lokijs

Answer 1

Answer №1

If you're working with LokiJS, you have a couple of options:

import * as Loki from 'lokijs';
const db = new Loki.default(`${UPLOAD_PATH}/${DB_NAME}`, { persistenceMethod: 'fs' });
// Personally, I find this method unattractive.

or

import Loki from 'lokijs';
const db = new Loki(`${UPLOAD_PATH}/${DB_NAME}`, { persistenceMethod: 'fs' });

Upon exploring the internals of lokijs, it appears that the class is exported as module.exports = factory(), which is essentially the same as export default factory(), meaning the class is exported as default. This concept can be better understood by reading this informative discussion on Stack Overflow: ES6: "import * as alias" vs "import alias"

Answer 2

If you're working with LokiJS, you have a couple of options:

import * as Loki from 'lokijs';
const db = new Loki.default(`${UPLOAD_PATH}/${DB_NAME}`, { persistenceMethod: 'fs' });
// Personally, I find this method unattractive.

or

import Loki from 'lokijs';
const db = new Loki(`${UPLOAD_PATH}/${DB_NAME}`, { persistenceMethod: 'fs' });

Upon exploring the internals of lokijs, it appears that the class is exported as module.exports = factory(), which is essentially the same as export default factory(), meaning the class is exported as default. This concept can be better understood by reading this informative discussion on Stack Overflow: ES6: "import * as alias" vs "import alias"

Error: Loki cannot be used as a constructor

Answer №1

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