Hono•3w ago

I can't use tsconfig `paths` when using Hono RPC in monorepo

I have monorepo with 2 packages, client & server (Hono).

.
├── bun.lockb
├── package.json
└── packages
    ├── client
    │   ├── package.json
    │   ├── src
    │   └── tsconfig.json
    └── server
        ├── package.json
        ├── src
        └── tsconfig.json

.
├── bun.lockb
├── package.json
└── packages
    ├── client
    │   ├── package.json
    │   ├── src
    │   └── tsconfig.json
    └── server
        ├── package.json
        ├── src
        └── tsconfig.json

I'm using Hono RPC for communication between client and server. It works perfectly, but when I define paths in tsconfig of server and rewrite import paths to use them, the Hono client does not infer the type correctly. This is my minimum reproducer: https://github.com/kota65535/hono-test And I've attached the screenshot when the type error occurs. This is likely due to my own misconfiguration, but any help or advice would be appreciated.

GitHub

GitHub - kota65535/hono-test

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8 Replies

ambergristle•3w ago

i haven't done a monorepo before, but this looks sort of funky to me: https://github.com/kota65535/hono-test/blob/7f1381ec2e8255fc5c758fd4247e054329a18dac/packages/client/package.json#L8 this might be helpful: https://leticia-mirelly.medium.com/a-comprehensive-guide-to-npm-workspaces-and-monorepos-ce0cdfe1c625

kota65535OP•3w ago

Hi @ambergristle , this is bun workspace. https://bun.sh/docs/install/workspaces

Bun

Workspaces – Package manager | Bun Docs

Bun's package manager supports workspaces and monorepo development workflows.

ambergristle•3w ago

@kota65535 i managed to get your example working by generating types for the server i.e., importing AppType from the d.ts file created during build unfortunately, it looks like bun's build process doesn't support that at this time. looks like there are some plugins that might help, but i'd recommend using tsc with emitDeclarationOnly to generate the types i'd also recommend taking a look at this: https://hono.dev/docs/guides/rpc#compile-your-code-before-using-it-recommended i did have a question about your project setup though. your actual client is an SPA or something, not a hono app serving html, right?

kota65535OP•3w ago

Thank you @ambergristle. Compiling and generating the type file is a bit tedious, but looks better than relying on the entire server code base.

your actual client is an SPA or something, not a hono app serving html, right?

Yes, the actual frontend is assumed to be SPA.

ambergristle•3w ago

my sense is that this is just part of working w monorepos all of the third-party packages you'd import are built, so it stands to reason that any internal dependencies would be as well definitely agree that it seems like a pain

kota65535OP•3w ago

Do you have any insight why it only works when the type file is shared? Types are too complex and TypeScript give up type inference?

ambergristle•3w ago

i'm not sure. that makes sense to me though it may just not be able to infer between projects like that by default there might be ways to work around it, but tbh it feels more like a feature than a flaw while it might be cumbersome to need to build your backend types, it feels good to have that firewall between client + server code

kota65535OP•3w ago

Thank you. It was frustrating that I couldn't figure out why the paths were not working, but I guess I shouldn't worry about it too much.

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I can't use tsconfig `paths` when using Hono RPC in monorepo

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