Lerna with Yarn, TypeScript and React Native: Cannot find module '@project/common' or its corresponding type declarations.ts(2307)

Question

The project uses Yarn, React Native, Lerna and Typescript. It is structured as a monorepo

Here is the structure:

project
|- packages
   | - mobile
       | - src
       | - packages.json
       | - tsconfig.json
   | - cloud-functions
       | - src
       | - packages.json
       | - tsconfig.json
   | - common1
       | - lib
       | - src
       | - packages.json
       | - tsconfig.json
   | - common2
       | - lib
       | - src
       | - packages.json
       | - tsconfig.json
| - packages.json
| - tsconfig.json
| - lerna.json

lerna.json looks like this:

{
  "packages": [
    "packages/*"
  ],
  "npmClient": "yarn",
  "version": "0.0.7",
}

The root packages.json looks like this:

{
  "name": "project",
  "private": true,
  "scripts": {
    ...
  },
  "devDependencies": {
    "@types/node": "^14.0.27",
    "lerna": "^3.22.1",
    "ts-node": "^8.10.2",
    "typescript": "^3.9.7"
  }
}

The root tsconfig.json looks like this:

{
  "compilerOptions": {
    "noImplicitAny": true,
    "noUnusedLocals": true,
    "removeComments": true,
    "noLib": false,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "sourceMap": true,
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "resolveJsonModule": true,
    "baseUrl": "./",
    "paths": {
      "@project/common1": ["packages/common1/lib"],
      "@project/common2": ["packages/common2/lib"],
      "@project/mobile": ["packages/mobile/src"],
      "@project/cloud-functions": ["packages/cloud-functions/src"],
    }
  },
  "exclude": ["node_modules", "**/*.spec.ts", "**/__tests__/*", "babel.config.js", "metro.config.js", "jest.config.js"]
}

The typical packages/common/packages.json looks like this:

{
  "name": "@project/common1",
  "version": "0.0.7",
  "main": "lib/index.js",
  "types": "lib/index.d.ts",
  "files": [
    "lib/**/*"
  ],
  "private": true,
  "devDependencies": {
    "@project/common2": "latest", //for common1 only
    "@types/node": "^14.0.27",
    "ts-node": "^8.10.2",
    "typescript": "^3.9.7"
  },
  "dependencies": {
    ...
  }
}

The typical packages/common/tsconfig.json looks like this:

{
  "extends": "../../tsconfig.json",
  "compilerOptions": {
    "module": "commonjs",
    "outDir": "lib",
    "strict": true,
    "target": "es6"
  },
  "compileOnSave": true,
  "include": ["src"]
}

The React Native file packages/mobile/packages.json looks like this:

{
    "name": "@project/mobile",
    "version": "0.0.7",
    "private": true,
    "dependencies": {
        "@project/common1": "latest",
        "@project/common2": "latest",
        ...
    },
    "devDependencies": {
        ...
        "ts-node": "^8.10.2",
        "typescript": "^3.8.3"
    },
}

I first ran into:

lerna ERR! yarn install --mutex network:42424 --non-interactive stderr:
warning Waiting for the other yarn instance to finish (19560)
warning Waiting for the other yarn instance to finish (21568)
error An unexpected error occurred: "https://registry.yarnpkg.com/@project%2fcommon1: Not found".

Obviously Yarn is trying to pull the dependencies from its packages registery. This fails.

Then I tried to remove the references to @project/common1 and @project/common2 in the dependencies of the packages.

In the source, VS Code underline the imports in red and prints:

Cannot find module '@project/common1' or its corresponding type declarations.ts(2307)

I also tried to use Yarn Workspace, yet I ran into modules hoisting issues with React Native. I did not want create a list of all possibly incompatible package, since it seems to be difficult to maintain.

"workspaces": {
  "nohoist": ["react-native", "react-native/**", "@react-native-community/checkbox", "@react-navigation/native"]
}

Is there a simple solution?

Or is it simpler for this use case to abandon Lerna and use GitHub based common repositories?

Answer 1

I don't know if this is the most simple approach but I could get it working by adding Yarn workspaces.

In the main packages.json I added:

  "workspaces": {
    "packages": [
      "packages/*"
    ],
    "nohoist": [
      "**mobile**",
      "**react**",
      "**react-native**",
      ...
    ]
  },

In Lerna.json I added:

  "useWorkspaces": true,

From the root tsconfig.json I deleted:

    "baseUrl": "./",
    "paths": {
      "@project/common1": ["packages/common1/lib"],
      "@project/common2": ["packages/common2/lib"],
      "@project/mobile": ["packages/mobile/src"],
      "@project/cloud-functions": ["packages/cloud-functions/src"],
    }