CODEWITHSUNDEEP
javascriptnode.js
ebyte
ebyte

Reputation: 1517

How nodejs reads and writes .env files？

How to read and write env files?

Original file：

# I am a note ...
key1=value1

key2=value2
   # I am a note ...

I need a function setEnv(key, value).

run setEnv('key1', 'value2')， Let it become：

# I am a note ...
key1=value2

key2=value2
   # I am a note ...

How can I achieve it?

Upvotes: 0

Views: 4583

Answers (3)

Gribesh Dhakal
Gribesh Dhakal

Reputation: 1454

Lets start by creating new project.

mkdir folder_name
cd folder_name
npm init

Then in your project directory install 'envfile' and 'dotenv'. Command for installing envfile is

npm install envfile --save

Similarly install dotenv

npm install dotenv --save

package dotenv directly reads .env file package envfile is used to parse and stringify the file as required. Create .env file in the project directory with your details.

# I am a note ...
key1=value1

key2=value2
   # I am a note ...

Create a new file with filename.js

After that for getting and setting env variables you can use following code.

const fs = require('fs');
require('dotenv').config()
const {
    parse,
    stringify
} = require('envfile');
const pathToenvFile = '.env';

/**
 * 
 * @param {string} key 
 * //Function to get value from env
 */
function getEnv(key) {
    console.log("Getting value of " + key);
    console.log(process.env[key]);
}
//Calling the function getEnv
getEnv("key1");


/**
 * 
 * @param {string} key 
 * @param {string} value 
 * //Function to set environment variables.
 */
function setEnv(key, value) {
    fs.readFile(pathToenvFile, 'utf8', function (err, data) {
        if (err) {
            return console.log(err);
        }
        var result = parse(data);
        result[key] = value;
        console.log(result);
        fs.writeFile(pathToenvFile, stringify(result), function (err) {
            if (err) {
                return console.log(err);
            }
            console.log("File Saved"); // Can be commented or deleted
        })

    });
}
//Calling the function setEnv
setEnv('key1', 'value2');

After this run your file using

node filename.js

You can get your desired output.

Initial .env file

# I am a note ...
key1=value1

key2=value2
   # I am a note ...

After running program

key1=value2
key2=value2

Yes your comments gets deleted.

Upvotes: 3

plc-dev
plc-dev

Reputation: 55

You can use the envfile module as described here.

const fs = require('fs');
const envfile = require('envfile');
const envPath = 'pathToEnvFile/.env';
let parsedFile = envfile.parseFileSync(envPath);
parsedFile.NEW_VAR = 'newVariableValue';
fs.writeFileSync(envPath, envfile.stringifySync(parsedFile));

Upvotes: 1

ebyte
ebyte

Reputation: 1517

Something like this：

function setEnv(envText, key, value) {
  if (!envText) {
    return;
  }
  const rp = new RegExp(`${key}=(.*?)\\s`);
  let result = envText.replace(rp, (m, $1) => {
    return m.replace($1, value);
  });
  if (!rp.test(result)) {
    result += `\n${key}=${value}`;
  }
  return result;
}

console.log(
  setEnv(
    `# I am a note ...
  key1=value1
  
  key2=value2
     # I am a note ...`,
    'key1',
    'value2',
  ),
);

But this doesn't work:

setEnv(
    `# I am a note ...
  key1=value1
  
  key2=value2`,
    'key2',
    'value1',
  )

setEnv(
    `# I am a note ...
  key1key2=value1
  
  key2=value2`,
    'key2',
    '2222',
  )

Upvotes: 0

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