React Native - Build config access from JS

Module to expose build config variables set in Gradle to your javascript code in React Native.

iOS version greatly contributed by maddijoyce

Install

npm i react-native-build-config

⚠️ For React Native < 0.60, use version 0.1.0 and use manual linking (see below)

Usage

Declare config variables in Gradle, under android/app/build.gradle:

android {
    defaultConfig {
        buildConfigField "String",  "API_URL",     '"https://myapi.com"'
        buildConfigField "Boolean", "SHOW_ERRORS", "true"
        ...

Or declare them in your info.plist file in your ios project.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
	<dict>
  <key>API_URL</key>
	<string>https://myapi.com</string>
  <key>SHOW_ERRORS</key>
  <true />
  ...

Then access those from javascript:

const BuildConfig = require('react-native-build-config')

BuildConfig.API_URL // "https://myapi.com"
BuildConfig.SHOW_ERRORS // true

Gradle sets some variables by default:

• VERSION_NAME and VERSION_CODE, both coming from the build settings. Keep in mind the code is a number
• APPLICATION_ID: Your package name, eg: com.Example
• DEBUG: set to true when running the app locally
• BUILD_TYPE and FLAVOR: more build settings

ProGuard/R8

ProGuard/R8 by default removes BuildConfig class from release Android build. JavaScript BuildConfig object will be undefined.

To keep it add the following line to proguard-rules.pro file

-keep class **.BuildConfig { *; }

You can replace ** with your.package.name.

Linking on React Native < 0.60

Native modules are auto-linked since v0.60. If you have a lower version, you need this:

1. Include this module in android/settings.gradle:

include ':react-native-build-config'
include ':app'

project(':react-native-build-config').projectDir = new File(rootProject.projectDir,
  '../node_modules/react-native-build-config/android')

2. Add a dependency to your app build in android/app/build.gradle:

dependencies {
    ...
    compile project(':react-native-build-config')
}

3. Change your main activity to add a new package, in android/app/src/main/.../MainActivity.java:

import com.ismaeld.RNBuildConfig.RNBuildConfigPackage; // add import

public class MainApplication extends Application implements ReactApplication {

  private final ReactNativeHost mReactNativeHost = new ReactNativeHost(this) {

      /* ... */

      @Override
      protected List<ReactPackage> getPackages() {
          return Arrays.<ReactPackage>asList(
                  new MainReactPackage(),
                  new RNBuildConfigPackage(BuildConfig.class), // add the package here
          );
      }
  };