process.env 变量给我 undefined in node/typescript

Question

My folder structure is like this:

backend/src/index.ts

backend/.env

backend/environment.d.ts

the 3 files have the following contents:

//index.ts
import express, {Application} from 'express';
import {config} from 'dotenv';
import {set, connect} from 'mongoose';

config({path: __dirname + '../.env'});

const MONGO_KEY = process.env.MONGO_KEY;
const PORT = 5000;
const HOST = 'localhost';

const app: Application = express();

const initDB = (key: string): void => {
  set('useCreateIndex', true);
  set('useFindAndModify', false);
  connect(key, {useNewUrlParser: true, useUnifiedTopology: true})
    .then(() => console.log('MongoDB connected!'))
    .catch((err: Error) => console.log(err));
};

console.log(MONGO_KEY);
if (MONGO_KEY) {
  initDB(MONGO_KEY);
}

app.listen(PORT, HOST, () =>
  console.log(`App running at http://${HOST}:${PORT}`)
);

---

//.env
MONGO_KEY="some_string"

---

// environments.d.ts
declare global {
  namespace NodeJS {
    interface ProcessEnv {
      MONGO_KEY: string;
    }
  }
}

export {};

The console.log of MONGO_KEY gives me undefined. I tried most of the solutions I found here and nothing worked so far. I have @types/node installed.

A second problem is the if check (I want to get rid of that). In the environment.d.ts file, I said that MONGO_KEY is a string, but ts thinks it's a string or undefined. I feel like I have to import the file somewhere.

EDIT: changing

config({path: __dirname + '../.env'});

to

config();

seemed to solve my problem. however, I changed it to that because it stopped working in the first place, so it's still weird.

EDIT 2: In case someone faces the same problem: I had routes imported from other files that had process.env variables in them and the dotenv.config() import was placed below those routes, so of course those variables were undefined.

Answer 1

If your js file is /home/alex/foo.js , then your __dirname is /home/alex .

This means that:

config({path: __dirname + '../.env'});

will become:

config({path: '/home/alex../.env'});

My general advice is: don't concatenate paths manually, use path.join() for consistent cross-platform behavior that adds/removes the exact correct amount of slashes.

Answer 2

use this command in your scripts: node -r dotenv/config your_main-file_name.js

for more details check out: https://www.npmjs.com/package/dotenv