How to Resolve Inability to Reference Internal Packages from Turborepo NestJS

When utilizing internal packages in a Turborepo project, frontend projects like Next.js function smoothly and can utilize internal packages without issues thanks to the transpilePackages configuration option.

However, backend projects like NestJS encounter errors when attempting to import internal packages directly.

e.g. error

"C:\Program Files\nodejs\npm.cmd" run start
 
> nest@0.0.1 start
> nest start               
 
Error: Cannot find module '@repo/database'
Require stack:

This issue can be circumvented by compiling internal packages to JavaScript before importing.

Solution

1. Install tsup in the Internal Package

npm i -D tsup -w <workspace>

e.g. For an internal package named data-access-db (assuming it uses PrismaClient):

npm i -D tsup -w packages/data-access-db

2. Modify the Internal Package's package.json

Configure the build command to export JavaScript files to the dist folder.

package.json

  "main": "./dist/index.js",
  "module": "./dist/index.mjs",
  "types": "./dist/index.d.ts",
  "scripts": {
    "build": "tsup src/index.ts --format cjs,esm --dts",
    "dev": "npm run build -- --watch"
  },

3. Build & Install the Internal Package Before Starting NestJS Project

npm run build -w <workspace>
npm i

e.g.

npm run build -w packages/data-access-db

As rebuilding the internal package every time you start NestJS is cumbersome, it's advisable to prepare a script in the top-level package.json to build and install internal packages before starting the NestJS project.