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Takuya Matsuyama

Posted on Sep 29, 2022

How to specify pre-processor flags to the JSI-based React Native libraries

#reactnative #ios #android #sqlite

Hi, it's Takuya.
I'm building a note-taking app called Inkdrop for mobile using React Native.

The app uses react-native-quick-sqlite, a fast wrapper of SQLite:

ospfranco / react-native-quick-sqlite

Fast SQLite for react-native.

    yarn add react-native-quick-sqlite
    npx pod-install

Quick SQLite embeds the latest version of SQLite and provides a low-level JSI-backed API to execute SQL queries. By using an embedded SQLite you get access the latest security patches and latest features.

Performance metrics are intentionally not posted, anecdotic testimonies suggest anywhere between 2x and 5x speed improvement.

Gotchas

Javascript cannot represent integers larger than 53 bits, be careful when loading data if it came from other systems. Read more.
It's not possible to use a browser to debug a JSI app, use Flipper (for android Flipper also has SQLite Database explorer).

API

/**
 * All SQLite command results will have at least this status definition:
 * Specific statements or actions can bring more data, relative to its context
 * status: 0 or undefined for correct execution, 1 for error
 *  message: if status === 1, here you will find error

…

View on GitHub

It embeds the latest version of SQLite in C/C++.
That means that you build SQLite from source in your RN project on Xcode and Android Studio (CMake).

It doesn't enable any compile-time options by default, and I needed to enable FTS5 for full-text search in my app.
It can be enabled by specifying a SQLITE_ENABLE_FTS5 pre-processor flag when compiling.

I've managed to enable FTS5 and I'd like to share how to do that in your project.
For Android, the library needs to make some changes. So, it'd be helpful for library maintainers who would support accepting custom build flags.

iOS

Fortunately, CocoaPods allows you to customize the pods project settings via Podfile:

https://guides.cocoapods.org/syntax/podfile.html

Add a post_install block to your <PROJECT_ROOT>/ios/Podfile like so:

post_install do |installer|
  installer.pods_project.targets.each do |target|
    if target.name == "react-native-quick-sqlite" then
      target.build_configurations.each do |config|
        config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] ||= ['$(inherited)', '<SQLITE_FLAGS>']
      end
    end
  end
end

Replace the <SQLITE_FLAGS> part with flags you want to add.
For example, you could add SQLITE_ENABLE_FTS5=1 to GCC_PREPROCESSOR_DEFINITIONS to enable FTS5 in the iOS project.

Android

The native modules are compiled with CMake that reads CMakeLists.txt.

CMake supports adding flags with add_definitions command.

Add the following lines in the library's CMakeLists.txt:

add_definitions(
  ${SQLITE_FLAGS}
)

It specifies flags via the variable SQLITE_FLAGS, which needs to be specified in react-native-quick-sqlite/android/build.gradle like so:

def SQLITE_FLAGS = rootProject.properties['quickSqliteFlags']

android {
  defaultConfig {
    externalNativeBuild {
        cmake {
            arguments '-DANDROID_STL=c++_shared',
              "-DREACT_NATIVE_VERSION=${REACT_NATIVE_VERSION}",
              "-DNODE_MODULES_DIR=${nodeModules}",
              "-DSQLITE_FLAGS='${SQLITE_FLAGS ? SQLITE_FLAGS : ''}'"
        }
    }