React native boolean values from .env are loaded as strings

[cervebar]

I have boolean value in my .env file written like this:

IS_DEVELOPMENT=true

And declared my env.d.ts like this:

declare module '@env' {
 ...
  export const IS_DEVELOPMENT: boolean
}

but when I use it in code:

import {IS_DEVELOPMENT} from '@env'
...
  console.log('IS_DEVELOPMENT', IS_DEVELOPMENT)
  console.log('IS_DEVELOPMENT', typeof IS_DEVELOPMENT)
  if (IS_DEVELOPMENT) {
    console.log('true value')
  } else {
    console.log('false value')
  }

not expected output is:

IS_DEVELOPMENT false
 LOG  IS_DEVELOPMENT string
 LOG  true value

In the previous version (2.6.2) we did the patch with dotenv-parse-variables for this (but I generally don't prefer patched solutions).

diff --git a/node_modules/react-native-dotenv/index.js b/node_modules/react-native-dotenv/index.js
index 7210d37..2d63eca 100644
--- a/node_modules/react-native-dotenv/index.js
+++ b/node_modules/react-native-dotenv/index.js
@@ -1,5 +1,6 @@
 const {readFileSync} = require('fs')
 const dotenv = require('dotenv')
+const dotenvParseVariables = require('dotenv-parse-variables');
 
 function parseDotenvFile(path, verbose = false) {
   let content
@@ -54,6 +55,7 @@ module.exports = ({types: t}) => ({
       })
       this.env = process.env
     }
+    this.env = dotenvParseVariables(this.env)
   },
 
   visitor: {

How do you solve this?
Can we somewhere say to the library that we actually want load env variables as booleans?
What are yours tips&tricks?

[goatandsheep]

My tips here would be to have a constants object and import from there

App.tsx

import {IS_DEVELOPMENT} from './constants'

constants.tsx

const constants = {
IS_DEVELOPMENT: process.env.IS_DEVELOPMENT === 'true' ? true : false
};
export default constants;

The counterintuitive part here is that the value you are checking for is not the default. i.e. if no value is set, it will take the default. So if you don't put a value, the above will default to false. if you do === 'false' ? false : true, then the code will default to true.

I will be covering this in my course I'll be launching this weekend.