Update build.gradle

[SaeedZhiany]

fixes #25145

Summary

Adding android Gradle plugin version and react-native version to ext. By that, the library developers can automatically read and use the root project's setting in the library's gradle and so, the whole project has been built with the same android gradle plugin and its dependency libraries rely on the same version of react-native. Also, putting these properties can cause a naming convention among library developers to avoid using an arbitrary name for reading these properties from the root project. (I currently using two libraries that use different names for getting android gradle plugin version just because of the lack of convention)

Note for library developers:
change your android build.gradle like this:

buildscript {
   +ext.safeExtGet = {prop, fallback ->
   +    rootProject.ext.has(prop) ? rootProject.ext.get(prop) : fallback
   +}
    repositories {
        jcenter()
        google()
    }

    dependencies {
        -classpath 'com.android.tools.build:gradle:3.4.1'
        +classpath("com.android.tools.build:gradle:${safeExtGet('gradlePluginVersion', '3.4.1')}")
    }
}

android {
    dependencies {
       -implementation 'com.facebook.react:react-native:+'
       +implementation "com.facebook.react:react-native:${safeExtGet('reactnativeVersion', '+')}"
    }
}

Changelog

[Android] [Added] - root project's android gradle plugin version and react-native version is now accessible for use in libraries' build.gradle files.

Test Plan

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[dulmandakh]

Usually it's not recommended to re-import Android Gradle Plugin to submodule, because it's already imported into root project, or RN app. So, I think it's not a proper solution to your problem. I would like to recommend you to change a native module to not use Android Gradle Plugin directly, but from root project.

[SaeedZhiany]

@dulmandakh
It seems there is a misunderstanding here.
I don't want to re-import the tool in sub module. actually I want to prevent to import and using multiple Android Gradle plugin version in one project. If you take a look at some RN libraries, you'll see some of them strictly using Android Gradle tool version lower than 3.4.1 (some of them using 2.x!!!) because it is not actively maintained by its maintainer. with multiple Gradle tool version, CI servers have to build project with multiple tools that I think it's not proper way.
(As a workaround I already wrote a script to replace the Gradle tool versions of project dependencies with project's Gradle tool version in my current project).
By this PR we can solve the problem in long term and users don't need to handle such cases.

[dulmandakh]

I understand the purpose of this PR, but you still need to make changes to libraries to make use of above changes. Instead, I would like to recommend to fix build.gradle to not use Android Gradle Plugin.

[dulmandakh]

About a year ago, I created a PR to RN to export Android SDK tools version configurations to be used in other libraries, and it helped a lot. I strongly believe that sub-projects or modules shouldn't be using Android Gradle Plugin.

[SaeedZhiany]

@dulmandakh
sorry but your statements couldn't convince me, please re-open this PR to having more discussion about it.

[dulmandakh]

could you please list modules you use and having problem?

[dulmandakh]

I created a PR to react-native-keychain oblador/react-native-keychain#227

[SaeedZhiany]

could you please list modules you use and having problem?

react-native-restart
react-native-svg
react-native-keychain
react-native-touch-id
react-native-community/async-storage
react-native-firebase
react-native-gesture-handler

[SaeedZhiany]

Also, create-react-native-module by @brodybits and react-native-create-library by @frostney are library template boilerplates, we can apply your suggestion in there too for fixing the problem for future RN libraries.

[cpojer]

What's the status of this PR?

[SaeedZhiany]

What's the status of this PR?

Hi @cpojer, I'm still waiting for someone to review the changes, unfortunately, @dulmandakh didn't respond from our last conversation.

[dulmandakh]

IMHO, Android Gradle Plugin should be loaded only once. Please correct me if wrong. This change will allow load AGP many times easily, or hide it. So I don't like the approach. It's best to fix third-party modules instead.