Amit DavidiandFacebook Github Bot
5df204b82d
Summary: Fix `react.gradle`'s handling of the case where a configuration isn't explicitly specified by the parent project - e.g. before importing to `build.gradle` files: ```groovy apply plugin: 'com.android.application' // Nothing to define: // project.ext.react = [ // ] apply from: "../../node_modules/react-native/react.gradle" ``` This is a _ridiculously_ subtle change but it is nevertheless important, as, combined with other groovy quirks, it can result in an overall misbehaviour of the build script. ### Source of the bug Currently, when a react build config _isn't_ specified by the user, RN's `react.gradle` falls back to `[]` (i.e. in [this line](https://github.com/facebook/react-native/blob/81a6b6ed3c54498f6f2148c106846352405949bf/react.gradle#L8)). In groovy, `[]` stands for an empty _array_ (actually, an empty `ArrayList` instance). The config, however, is expected to have the nature of a `Map`. ### Effects of the bug As a bottom line, whenever a configuration isn't specified, the evaluation of [the condition](https://github.com/facebook/react-native/blob/81a6b6ed3c54498f6f2148c106846352405949bf/react.gradle#L184) as to whether the bundling task in question should be enabled, results in the following build-time exception: ``` FAILURE: Build failed with an exception. * Where: Script '/Users/...../node_modules/react-native/react.gradle' line: 179 * What went wrong: A problem occurred configuring project ':app'. > Could not create task ':app:bundleDebugJsAndAssets'. > Could not find method enabled() for arguments [[]] on task ':app:bundleDebugJsAndAssets' of type org.gradle.api.tasks.Exec. * Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights. * Get more help at https://help.gradle.org BUILD FAILED in 9s ``` I'm not much of a Groovy person, but while digging in, I've learned that it has the following odd attribute to it: When accessing a non-existing property of an empty `ArrayList` in a bean-like fashion (i.e. as `array.property1` rather than `array.getProperty('property1')`), a new empty array is returned. This only holds true for _empty_ arrays, as illustrated by the following snippet: ```groovy def emptyArr = [] def arr = [40, 2] def result1 = (emptyArr.uninitializedProp == null) println "$result1, ${emptyArr.uninitializedProp}" // ==> false, []" def result2 = (arr.uninitializedProp == null) // ==> MissingPropertyException println result2 // Never reached ``` While this whole scheme could be a bug, it's nonetheless effective in both the latest 2.x.x groovy version and in 2.1.0 (which is the oldest one that seems to be available for download nowadays). The point being is that its a behavior that's sticked. Note that other evaluations of `config` properties (e.g. [lines 10-19](https://github.com/facebook/react-native/blob/81a6b6ed3c54498f6f2148c106846352405949bf/react.gradle#L10)) in the script are not effected by this as they are initially only examined in a boolean form, rather than using a null comparison; "Lucky" for us, empty arrays evaluate to `false`. ### Fix Simply fallback to a groovy map rather than an array whenever `config` hasn't been specified. Namely, initialize it to `[:]`, which results in a new `HashMap` instance, rather than `[]`. ### Workaround Until effectively fixed, can be worked-around by explicitly setting config to an empty map before the react gradle script is imported by the user: ```groovy apply plugin: 'com.android.application' project.ext.react = [:] apply from: "../../node_modules/react-native/react.gradle" ``` ## Changelog [Android] [Fixed] - Fix 'Could not create task ':app:bundleDebugJsAndAssets'.' error in project with no react config Pull Request resolved: https://github.com/facebook/react-native/pull/27101 Test Plan: Mostly regression is required here. I've myself ran this over a project with an empty config and the app has launched successfully in both `release` and `debug` flavors. Differential Revision: D18298542 Pulled By: cpojer fbshipit-source-id: 88b4715b75f190003c4813e5324a5094a7779f67
React Native
Learn once, write anywhere:
Build mobile apps with React.
Getting Started · Learn the Basics · Showcase · Contribute · Community · Support
React Native brings React's declarative UI framework to iOS and Android. With React Native, you use native UI controls and have full access to the native platform.
- Declarative. React makes it painless to create interactive UIs. Declarative views make your code more predictable and easier to debug.
- Component-Based. Build encapsulated components that manage their state, then compose them to make complex UIs.
- Developer Velocity. See local changes in seconds. Changes to JavaScript code can be live reloaded without rebuilding the native app.
- Portability. Reuse code across iOS, Android, and other platforms.
React Native is developed and supported by many companies and individual core contributors. Find out more in our ecosystem overview.
Contents
- Requirements
- Building your first React Native app
- Documentation
- Upgrading
- How to Contribute
- Code of Conduct
- License
📋 Requirements
React Native apps may target iOS 9.0 and Android 4.1 (API 16) or newer. You may use Windows, macOS, or Linux as your development operating system, though building and running iOS apps is limited to macOS. Tools like Expo can be used to work around this.
🎉 Building your first React Native app
Follow the Getting Started guide. The recommended way to install React Native depends on your project. Here you can find short guides for the most common scenarios:
📖 Documentation
The full documentation for React Native can be found on our website.
The React Native documentation discusses components, APIs, and topics that are specific to React Native. For further documentation on the React API that is shared between React Native and React DOM, refer to the React documentation.
The source for the React Native documentation and website is hosted on a separate repo, @facebook/react-native-website.
🚀 Upgrading
Upgrading to new versions of React Native may give you access to more APIs, views, developer tools, and other goodies. See the Upgrading Guide for instructions.
React Native releases are discussed in the React Native Community, @react-native-community/react-native-releases.
👏 How to Contribute
The main purpose of this repository is to continue evolving React Native core. We want to make contributing to this project as easy and transparent as possible, and we are grateful to the community for contributing bug fixes and improvements. Read below to learn how you can take part in improving React Native.
Code of Conduct
Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.
Contributing Guide
Read our Contributing Guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to React Native.
Open Source Roadmap
You can learn more about our vision for React Native in the Roadmap.
Good First Issues
We have a list of good first issues that contain bugs which have a relatively limited scope. This is a great place to get started, gain experience, and get familiar with our contribution process.
Discussions
Larger discussions and proposals are discussed in @react-native-community/discussions-and-proposals.
📄 License
React Native is MIT licensed, as found in the LICENSE file.
React Native documentation is Creative Commons licensed, as found in the LICENSE-docs file.