React Native Dotenv Using environment variables in React Native

The base set of variables will be .env and the environment-specific variables will overwrite them. Notice the moduleName value is “@env” so we’ll use this to import our key/value pair.

• I used the __DEV__ polyfill that is built into react-native in order to solve this problem.
• An environment variable is a variable who’s value is set from outside the program.
• And this is in babel-ecosystem, so I should learn how to write a babel plugin…
• What I did was put a configuration files within S3 with my different environments.
• By default, defining the APP_ENV variable can be used to set your preferred environment, separate from NODE_ENV.
• It is possible to access the variables with process.env.blabla instead of process.env[‘blabla’].

For nextjs, you must set moduleName to react-native-dotenv. In general, Release is production and Debug is development. Learn how to use react-native-dotenv by viewing and forking example apps that make use of react-native-dotenv on CodeSandbox.

Building a custom Flutter ScrollView

Then just import from ‘../vars’and you’ll always get the correct one. Unfortunately, this wont work if you want more than two environments, but its easy and doesn’t involve adding more dependencies to your project. I used the __DEV__ polyfill that is built into react-native in order to solve this problem. It is automatically set to true so long as you are not building react native for production. In each method, we first checked the environment, then dynamically called the corresponding env variable.

• To answer how to expose your environment to react-native, I suggest using Babel’s babel-plugin-transform-inline-environment-variables.
• It can often take away the friction of using Xcode and Android studio as it allows you to test your app directly on your phone.
• It is automatically set to true so long as you are not building react native for production.
• We could also switch to the staging environment to make sure everything is okay and nothing breaks before we push to production.
• @DamonYuan that depends entirely on how you’re setting up your packages.
• This is due to the fact that babel-loader computes a cacheIdentifier that does not take your environment into account.

Environment variables are essentially values that will be set outside your code. They will be set at runtime by the environment that your app is running on, such as your production server or your computer. As you can see above, we defined our custom env variables using the REACT_APP_ prefix. Next, let’s create our .env file in our root folder. The .env file is a text file we will use to define our variables, as shown below.

Files

All referenced imported members are replaced as the values specified in the .env file. The variables will automatically be pulled from the appropriate environment and development is the default. One thing that we’ve noticed is that metro overwrites the test environment variable even if you specify a config, so we’ve added a way to fix this. By default, defining the APP_ENV variable can be used to set your preferred environment, separate from NODE_ENV. Expo is a very useful environment that can help you create and distribute your React Native apps. It can often take away the friction of using Xcode and Android studio as it allows you to test your app directly on your phone.

Let’s say we already have a live version of our application, but we want to add a new feature or make some other change. We do not want to make this change in the production environment because we might break the application.

Using env variables to switch between API endpoints in different environments

React native does not have the concept of global variables. It enforces modular scope strictly, in order to promote component modularity and reusability. In case of Android, variables are available also in Java classes, gradle, AndroidManifest.xml etc. In case of iOS, variables are available also in Obj-C classes, Info.plist. Now we need to configure the package to work with Babel.

Some of its downsides are that it does hide plenty of configurations from you and there isn’t as much help with error handling out there as I would like. Install babel-plugin-transform-inline-environment-variables by running npm i babel-plugin-transform-inline-environment-variables –save-dev. Using Constants.manifest we can access the object inside extra. So if your environment variable was development, this code should console.log “dogs are cool”. I used react-native-config to set up multiple environments for my project.

React Native Dotenv – Using environment variables in React Native

I created a small Expo typescript template repo so you can check. Purely for the sake of reproducibility, I also added the .env file with a dummy entry. The specific method used to set environment variables will vary by CI service, build approach, platform and tools you’re using. You have to clear bundler’s cache by running react-native start –reset-cache every time you change the environment variables. If you need to keep a value private, it’s best to store these on your backend.

Variables are one of the fundamental components of programming languages. In JavaScript, a variable stores the value of data types such as integers, strings, and more. The value or data type of a variable can be changed later. The tests that use require(‘@env’) are also not passing.

Checking the environment and dynamically calling the env variable

It both describes the keys required to run the app, as well as the filename expected once copied and renamed. The pattern is common in Ruby apps using the dotenv gem, which is where I lifted the pattern from. React Native Dotenv is a Babel plugin that allows you to use dotenv values in your React Native project. It takes the enviroment variables we set and replaces the variable with the value when our app builds. Instead, we will have to switch to the development environment, make the necessary changes, and test. We could also switch to the staging environment to make sure everything is okay and nothing breaks before we push to production.