So I have my module written as such

import mongoose from 'mongoose';

export class MyModule {
   constructor(){
       //do
   }

   create(str){
      mongoose.connect(str); //cannot find property 'connect' of undefined
   }

}

When using the import syntax, I get the cannot find property 'connect' of undefined error; it works as intended when using require.

Weirdly enough, importing individual properties via import syntax works as intended,

import { connect } from 'mongoose'

but I need access to the entire ORM for some other reasons.

Why is it like so? Am I doing something wrong? To be fair, I don't have much experience in ES6 module system, TypeScript and Node.js so I might be missing something here.

I'm running this on Node.js with NestJS, on a typescript file.

So I have my module written as such

import mongoose from 'mongoose';

export class MyModule {
   constructor(){
       //do
   }

   create(str){
      mongoose.connect(str); //cannot find property 'connect' of undefined
   }

}

When using the import syntax, I get the cannot find property 'connect' of undefined error; it works as intended when using require.

Weirdly enough, importing individual properties via import syntax works as intended,

import { connect } from 'mongoose'

but I need access to the entire ORM for some other reasons.

Why is it like so? Am I doing something wrong? To be fair, I don't have much experience in ES6 module system, TypeScript and Node.js so I might be missing something here.

I'm running this on Node.js with NestJS, on a typescript file.

• javascript
• typescript
• mongoose
• ecmascript-6
• nestjs

• Has it installed mongoose in the node_modules? was there any error in npm installation? – nivendha Commented Aug 7, 2019 at 6:24
• 1 To be clear, when you replace the first line of your code example with const mongoose = require('mongoose'); it works? Are you executing this code with Node.js? – Patrick Hund Commented Aug 7, 2019 at 6:25
• @nivendha Yea, I have it in my package.json already and it's also existing in the node_modules folder – Potato Salad Commented Aug 7, 2019 at 6:25
• @PatrickHund Yes and yes, and I'm using NestJS as a framework – Potato Salad Commented Aug 7, 2019 at 6:26
• 2 import * as mongoose from 'mongoose'; try this – Binit Ghetiya Commented Aug 7, 2019 at 6:34

4 Answers 4

There are total 2 syntex we can use here.

ES15 (NodeJS)

const mongoose = require('mongoose');

then use mongoose.connect

ES16 (import/export)

import * as mongoose from `mongoose`;

then use mongoose.connect

or

import {connect} from `mongoose`;

then use connect directly

In your tsconfig.json file, you can set

"allowSyntheticDefaultImports": true,
"esModuleInterop": true

This will allow you to use the syntax

import mongoose from 'mongoose';

After installing @types/mongoose, VS Code reports that mongoose does not have a default export (all being named exports) that being the case, doing

import mongoose from `mongoose`

will not work. This also explains why getting individual properties instead works:

import { connect } from `mongoose`

As a workaround, thanks to @Binit Ghetiya who first mentioned it in this thread, you should do this instead:

import * as mongoose from `mongoose`

Which piles every named export from Mongoose into the variable mongoose.

Just change the import as follows:

import * as mongoose from 'mongoose';

Here is an example:

import * as mongoose from 'mongoose';

export class MyModule {

   constructor(){
       //do
   }

   create(str){
      mongoose.connect(str);
   }
}