Path mappings to files resolve incorrectly

[jneuendorf-i4h]

Hi,

thanks for your package. It's a shame tsc doesn't compile its resolution behavior.

Scenario

In my scenario, I generated JSON files from my TypeScript code (JSON schema from types).
In order to avoid import errors, I configured my path mappings so that JSON are preferred over source files:

{
  "compilerOptions": {
    "rootDir": "src/",
    "baseUrl": "src/",
    "outDir": "dist/",
    "paths": {
      "~/*": ["./*"],
      "@schema/*": ["./schema/*.json", "./schema/*"],
    },
  }
}

The files are structured like this:

src/schema/
├── a.json
└── a.ts

and an import like this: import { definitions } from "@schema/a".

Expected behavior

This setup works fine with TypeScript. Since I think this package aims to mimic TypeScript's resolution mechanism, just at compile time, I think, this setup should also work with your package.

Actual behavior

The JSON file is not resolved. Instead the compiled JS file is resolved.

At first I thought, the reason is that I used --ext incorrectly. But after some debugging, I found that the import is resolved to .../src/schema/*.json/a and then disregarded. This result is produced by https://github.com/benyap/resolve-tspaths/blob/main/src/steps/generateChanges.ts#L143

resolve(aliasPath, importSpecifier.replace(prefix, ""))

In my understand, this code assumes that all aliasPaths are pointing to directories, which is not necessarily true (as described above). I guess replacing "*" in the path instead of appending to it (in case the alias is not a directory), could solve this issue.

(aliasPath) => isDirectory(aliasPath)
    ? resolve(aliasPath, importSpecifier.replace(prefix, ""))
    : aliasPath.replace("*", importSpecifier.replace(prefix, ""))

Let me know what you think. 😉

[benyap]

Hi @jneuendorf-i4h, thanks for your issue and presenting it very clearly!

Normally, I would import a JSON file using the .json to differentiate it from a module:

import { ... } from "@schema/a.json";
// vs
import { ... } from "@schema/a";

I wasn't even aware that you could import a JSON file without using a .json extension 😂 but I tested it and you are right, the Typescript language server seems to be happy with importing a JSON file without .json if you have "./schema/*.json" as a path mapping.

I will note that if you don't have "...*.json" in the path mapping, you cannot import a JSON file without the .json extension. As you pointed out, it looks like Typescript uses * as a wildcard to match directories and files.

I can take a deeper look into your suggestion when I have time - or feel free to open a PR. Initial thoughts are that it looks like it could work, though it will need to be tested thoroughly.

In the interim, is there a reason why you can't import the file with a .json extension? resolve-tspaths will map your paths correctly if you simply do that 😉

[jneuendorf-i4h]

Hey @benyap, thanks for the quick reply.

I actually ended up, importing the JSON files explicitly (so like import ... from "./a.json"). Therefore, I am not relying on the requested behavior anymore.

You mentioned that such a feature would need to be well tested and I agree. So if the requested behavior is a bit exotic (and most users don't need it), it may not be worth increasing the complexity of the project. However, it would be helpful to state this caveat¹ in the README so people know what they're up to.

---

¹ meaning that only file paths can be correctly resolved

[github-actions]

This issue is stale because it has been open for 30 days with no activity.

[benyap]

Thanks @jneuendorf-i4h for the suggestion, will update the README!

[benyap]

@all-contributors add @jneuendorf-i4h for documentation

[allcontributors]

@benyap

I've put up a pull request to add @jneuendorf-i4h! 🎉