lerna yarn workspaces and typescript project reference

[jaimesangcap]

I have this sample repo branch tsconfig-paths-issue https://github.com/jaimesangcap/lerna-ts-monorepo/tree/tsconfig-paths-issue
using lerna, yarn workspaces and typescript project references but it does not seem to work.

It cannot resolve the relative path of the module with error:

module.js:545
    throw err;
    ^

Error: Cannot find module '@elts/common/testing/seed'
    at Function.Module._resolveFilename (module.js:543:15)
    at Function.Module._resolveFilename (/Users/jaime/sanay/lerna-ts-monorepo/node_modules/tsconfig-paths/lib/register.js:75:40)
    at Function.Module._load (module.js:470:25)
    at Module.require (module.js:593:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/Users/jaime/sanay/lerna-ts-monorepo/packages/api/lib/index.js:3:14)
    at Module._compile (module.js:649:30)
    at Object.Module._extensions..js (module.js:660:10)
    at Module.load (module.js:561:32)
    at tryModuleLoad (module.js:501:12)

to reproduce:

npx lerna bootstrap at project root
tsc -b
TS_NODE_PROJECT=tsconfig.settings.json node -r tsconfig-paths/register packages/api/lib/index.js

then error above should show

[jonaskello]

You may want to take a look at this example.

[jaimesangcap]

@jonaskello Actually that's the one I'm following along 😄
I've got it working in this branch tsconfig-paths-solved https://github.com/jaimesangcap/lerna-ts-monorepo/tree/tsconfig-paths-solved

the only difference is that in the tsconfig.json, I'm pointing the path to the transpiled path and not the source.

NOT working:
tsconfig.json

"paths": {
      "@elts/common/*": ["./common/src/*"]
    }

WORKING:

"paths": {
      "@elts/common/*": ["./common/lib/*"]
    }

Do you have idea why is that?

[flash1293]

You are mixing js and ts execution contexts here.

If you are executing node -r tsconfig-paths/register packages/api/lib/index.js, you are using solely the js files - the only thing typescript-related are the path-resolutions, but node is always looking for js files. Since there are no js files in common/src, only ts files, node doesn't know what to do.

If you are executing ts-node -r tsconfig-paths/register, you can use either js files or ts files, ts-node knows how to deal with both of them (ts-node -r tsconfig-paths/register packages/api/lib/index.js or ts-node -r tsconfig-paths/register packages/api/src/index.ts).

If you don't need the compiled js files and using ts-node is fine for you, just skip the compilation step completely and map everything to the src folders -

"paths": {
      "@elts/common/*": ["./common/src/*"]
    }

and
ts-node -r tsconfig-paths/register packages/api/src/index.ts

[jaimesangcap]

That makes sense, thank you for explaining. For now I guess I will just use ts-node