CODEWITHSUNDEEP
javascriptreact-nativenode-modulesmetro-bundler
Will
Will

Reputation: 557

Metro extraNodeModules does not work - Error: Unable to resolve module

I have an existing React native app. I would like to create another and share some code between them. I made use of Metro extraNodeModules to import the shared code into either app. In either app, I expect to be able to do for example:

// MyApp1/src\navigation\app.navigator.js
import { someUtilModule } from 'shared';

Unfortunately when the app bundle is loading on my development device, it fails with:

error: Error: Unable to resolve module `shared` from `src\navigation\app.navigator.js`: shared could not be found within the project or in these directories:
  C:\path\to\my\project

If you are sure the module exists, try these steps:
 1. Clear watchman watches: watchman watch-del-all
 2. Delete node_modules: rm -rf node_modules and run yarn install
 3. Reset Metro's cache: yarn start --reset-cache
 4. Remove the cache: rm -rf /tmp/metro-*
    at ModuleResolver.resolveDependency (C:\path\to\my\project\MyApp1\node_modules\metro\src\node-haste\DependencyGraph\ModuleResolution.js:186:15)
    at ResolutionRequest.resolveDependency (C:\path\to\my\project\MyApp1\node_modules\metro\src\node-haste\DependencyGraph\ResolutionRequest.js:52:18)
    at DependencyGraph.resolveDependency (C:\path\to\my\project\MyApp1\node_modules\metro\src\node-haste\DependencyGraph.js:287:16)
    at Object.resolve (C:\path\to\my\project\MyApp1\node_modules\metro\src\lib\transformHelpers.js:267:42)
    at C:\path\to\my\project\MyApp1\node_modules\metro\src\DeltaBundler\traverseDependencies.js:434:31
    at Array.map (<anonymous>)
    at resolveDependencies (C:\path\to\my\project\MyApp1\node_modules\metro\src\DeltaBundler\traverseDependencies.js:431:18)
    at C:\path\to\my\project\MyApp1\node_modules\metro\src\DeltaBundler\traverseDependencies.js:275:33
    at Generator.next (<anonymous>)
    at asyncGeneratorStep (C:\path\to\my\project\MyApp1\node_modules\metro\src\DeltaBundler\traverseDependencies.js:87:24)

Folder Structure (The shared folder exists - this is output from tree):

C:\path\to\my\project
├── MyApp1
│   └── src
│       ├── app
│       ├── assets
│       ├── components
│       ├── core
│       ├── navigation
│       ├── scenes
│       └── services
├── MyApp2
│   └── src
│       ├── app
│       ├── assets
│       ├── components
│       ├── core
│       ├── navigation
│       ├── scenes
│       └── services
└── shared
    ├── assets
    ├── components
    ├── navigation
    ├── scenes
    └── services

My metro configuration:

// ...
const sharedDir = path.resolve(`${__dirname}/../shared`);
const extraNodeModules = {
  shared: sharedDir,
};
const watchFolders = [sharedDir];

module.exports = {
  transformer: /*...*/,
  resolver: {
    extraNodeModules: new Proxy(extraNodeModules, {
      get: (target, name) => {
        // redirects dependencies referenced from shared/ to local node_modules
        return name in target
          ? target[name]
          : path.join(process.cwd(), `node_modules/${name.toString()}`);
      },
    }),
  },
  watchFolders,
}

Upvotes: 5

Views: 3096

Answers (1)

Will
Will

Reputation: 557

I ultimately got around this by creating a dummy package.json file in the shared/:

{
  "name": "shared",
  "version": "0.0.1"
}

At a much later date I removed that file and the project continued to work...

Right now, it might be worth completely emptying cache, temp files, etc. before resorting to a dummy package.json

Upvotes: 1

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