This repo is attempting to show a problem when attempting to utilize TypeORM CLI's migrate:generate functionality when using react-native driver.

Initial Detection of Bug

If we follow TypeORM's guide to adding ts-node to your project, then run yarn ts-migrate to execute typeorm migration:generate -n InitialProd, it will give an error that doesn't seem quite right:

Error during migration generation:
DriverPackageNotInstalledError: React-Native package has not been found installed. Try to install it: npm install react-native-sqlite-storage --sav

While this error can be a problem, even once you've installed the package properly, we still get this error.

Because of the way error handling is built in ReactNativeDriver currently, we're getting a false-positive here. If we modify the source code to add a simple console.error statement, we get this error:

$ node --require ts-node/register ./node_modules/typeorm/cli.js migration:generate -n InitialProd
C:\Users\crutchcorn\git\OceanBit\RN\External\typeorm-rn-migrate-bug-repro\node_modules\react-native\index.js:14
import typeof AccessibilityInfo from './Libraries/Components/AccessibilityInfo/AccessibilityInfo';
       ^^^^^^

SyntaxError: Unexpected token typeof
    at Module._compile (internal/modules/cjs/loader.js:703:23)
    at Module._extensions..js (internal/modules/cjs/loader.js:770:10)

If you're not wanting to deal with yarn link and the complexity of debugging that adds, you can edit the compiled source code of typeorm to see the correct error. Simply edit:

./node_modules/typeorm/driver/react-native/ReactNativeDriver.js

On Line 83, there's a try/catch. In the catch, add a console.error statement.

This error now properly contextualized, it seems that what's actually going wrong is that react-native's index.js file is written in Flow. Because ts-node doesn't know how to handle flow, it simply throws a syntax error when it reaches invalid JavaScript syntax.

Naive Attempted Solution

While ts-node is unable to detect flow properly, babel is. With the package @babel/node/babel-node, we're able to run babel over typeorm's CLI. Then, utilizing the official RN babel plugin (currently metro-react-native-babel-preset), it should be able to compile React Native for us.

While we ultimately needed more configuration to make this concept work in practice, when we finally completed it we added the new commands to the package.json:

"babel-typeorm": "babel-node -x .ts --config-file ./babel.config.js ./babel-register.js",
"babel-migrate": "yarn babel-typeorm migration:generate -n InitialProd"

Sure enough, once these changes are made, yarn babel-migrate no longer throws the error we were getting.

However, we get a new error (once we make the changes to the typeorm source code to fix the incorrect error message issue):

$ babel-node -x .ts --config-file ./babel.config.js ./babel-register.js migration:generate -n InitialProd
Invariant Violation: __fbBatchedBridgeConfig is not set, cannot invoke native modules
    at invariant (C:\Users\crutchcorn\git\OceanBit\RN\External\typeorm-rn-migrate-bug-repro\node_modules\invariant\/invariant.js:40:15)
    at Object.<anonymous> (C:\Users\crutchcorn\git\OceanBit\RN\External\typeorm-rn-migrate-bug-repro\node_modules\react-native\Libraries\BatchedBridge\/NativeModules.js:177:3)

It was then that I realized the true scope of the problem.

Deeper Explaination

While other drivers have the ability to run on the development machine natively, the react-native driver is unable to do this currently. This is because in order to do so, we'd need to spin up an instance of react-native running on their native platforms. While this might be theoretically possible for react-native-windows and react-native-macos, that would leave platforms like Linux in the dust. react-native-macos is also not well documented currently, and the performance of spinning up an app instance simply for a migration feels like a waste of resources.

Further, even if we did get that infrastructure in place, we're then limited by the platforms supported by react-native-sqlite-storage. While it seems there is windows support in the library, there doesn't appear to be the same for macOS yet.

However, we already have sqlite as a driver supported in TypeORM... Maybe we could add conditional logic to typeorm's CLI to detect if the platform is react-native and run the migration on that platform? I'm admittedly unsure if there are complications in doing so that I simply am not aware of currently.

P.S.

"If I had more time, I would have written a shorter letter"

• Unknown

This was long-winded... I guess that's what happens when you start coding at 2AM, spend hours and hours modifying CJS source code, tinkering with babel plugins, and then realize that the problem has more nuance than you originally thought.

I'm going to sleep now lol