Controller loading doesn't work in compiled apps

[ben-ryder]

Package Information: kangojs, all versions

Describe the bug
When passing a controllerFilesGlob to KangoJS it will be a glob of typescript files, for example src/modules/**/*.controller.ts.
When the app is compiled to JS this reference stays the same and so the compiled app fails to import the controllers as Typescript files can't be imported into the compiled JS.

To Reproduce
Steps to reproduce the behaviour:

1. Setup KangoJS with a controller files glob that points to typescript files (such as src/modules/**/*.controller.ts).
2. When running via ts-node this will work fine.
3. When attempting to run the compiled JS app an error will occur.

In my application the error is as follows:

err: {
  "type": "SyntaxError",
  "message": "Cannot use import statement outside a module",
  "stack":
      /home/<path>/api/src/modules/albums/album.controller.ts:1
      import { NextFunction, Response } from 'express';
      ^^^^^^
      
      SyntaxError: Cannot use import statement outside a module
          at wrapSafe (internal/modules/cjs/loader.js:984:16)
          at Module._compile (internal/modules/cjs/loader.js:1032:27)
          at Object.Module._extensions..js (internal/modules/cjs/loader.js:1097:10)
          at Module.load (internal/modules/cjs/loader.js:933:32)
          at Function.Module._load (internal/modules/cjs/loader.js:774:14)
          at Module.require (internal/modules/cjs/loader.js:957:19)
          at require (internal/modules/cjs/helpers.js:88:18)
}
             

Expected behaviour
I'm unsure at the moment. Ideally the solution should not require any changes from a user perspective.
Can KangoJS somehow hook into the typescript build to change that string?
When loading could KangoJS use tsconfig.json to transform the path if it detects it's running with JS not TS?

Additional context
This could just be a fundamental problem with typescript & builds. It will probably be a good idea to see if this is an
issue other frameworks or libraries have needed to solve.

[ben-ryder]

Temporary Workaround (NOW OLD, SEE BELOW)

A temporary workaround is to check if the current file being executed is a .js or .ts file and then pass a different controllerFilesGlob to KangoJS depending on the answer.

For example:

const TYPESCRIPT_ACTIVE = __filename.endsWith('ts');
const controllerFilesGlob = TYPESCRIPT_ACTIVE 
  ? 'src/modules/**/*.controller.ts' 
  : 'dist/src/modules/**/*.controller.js'; // set glob to compiled files if running JS

const kangoJS = new KangoJS({
    globalPrefix: "/api/v2",
    controllerFilesGlob,
});
await kangoJS.boostrap(app);

I'm calling this a "temporary" workaround as I'm hoping there will be a solution that doesn't involve extra code from a user's perspective

[ben-ryder]

A possible solution could be something like https://stackoverflow.com/a/59607836:

join(__dirname, '**', '*.entity.{ts,js}')

Using __dirname it would be possible to automatically get either the src or build directory, then {ts,js} will cause the correct files to load.
While this doesn't completely hide this gotcha from a user, it helps reduce the code required to overcome it.

An example could look something like this:

const kangoJS = new KangoJS({
    globalPrefix: "/api/v2",
    controllerFilesGlob: join(__dirname, 'src/modules/**/*.controller.{ts,js}'),
});

Initial testing suggest this approach works fine.

[ben-ryder]

If a solution like one of the two above is always going to be required to overcome this issue, I would rather keep this as something the user can choose to manage how they wish.
I fear that any implementation I build into KangoJS will be so dependent on certain tsconfig and Typescript build settings that attempting to support a one-size-fits-all solution would cause even more issues.

[ben-ryder]

TODO

• update code examples to include the second solution
• update docs to explicitly highlight this issue