Nest: IOC resolve can't import from index.ts, but it's COPY index2.ts is ok.

[muyu66]

[x] Bug report

If code is:

import { UserDao } from './daos'; // only use daos/index.ts to export

@Injectable()
export class UserService extends BaseService {

constructor(
    private readonly dao:UserDao,
) {
    super();
}

It throw a error:

[ExceptionHandler] Nest can't resolve dependencies of the UserService (?). Please verify whether [0] argument is available in the current context.

Now we adjust code:

import { UserDao } from './daos/user.dao';

Then everything is right. It's amazing.

File /daos/index.ts

export { UserDao } from './user.dao';

Version

"@nestjs/common": "^5.0.1",
"@nestjs/core": "^5.0.1",
"typescript": "^2.9.2"

I think it's bug, IOC resolve can't import from index.ts

[adrien2p]

hey @muyu66 could you show us your module definition ?

[muyu66]

@adrien2p
I try to build minimized sample program, but i am fail. I am not able to reply this mistake in new Project.

When code "import { UserDao } from './daos/index'", it throw Error.
When code "import { UserDao } from './daos/index2'", it is just normal, index2.ts is index.ts's COPY

Under these circumstances, I think my module definition is not related to this

[adrien2p]

what are your compiler options in your tsconfig.json file ?
even if your specify './daos/index' that doesn't work ?

[BrunnerLivio]

I also experienced some really strange behaviour like @muyu66 described. Seems like a bug with the module resolution to me. Do not know if it is a bug of TS or Nest though.

[muyu66]

@adrien2p

This is my tsconfig.json

{
    "compilerOptions": {
        "module": "commonjs",
        "target": "es6",
        "noImplicitAny": false,
        "removeComments": false,
        "outDir": "build",
        "emitDecoratorMetadata": true,
        "experimentalDecorators": true,
        "pretty": true,
        "strictNullChecks": true
    },
    "include": [
        "src/**/*"
    ]
}

Yes, i try "./dao/index" and "./dao"

[muyu66]

Let us continue to observe whether there are more examples. I cannot unilaterally reproduce

[muyu66]

@adrien2p @BrunnerLivio
I often run into such problems and then found examples of stable recurring today. I wrote a minimum project (fork from typescript-starter).

This problem can be reproduced by "npm run dev"

Project is in: (branch is resolve)
https://github.com/muyu66/typescript-starter/tree/resolve

[BrunnerLivio]

@muyu66 Yup also able to reproduce it.

[muyu66]

I don't understand the internal ioc implementation mechanism of Nestjs, I try to read its source code, still can't understand.

I am currently using a solution to circular dependencies to temporarily circumvent this problem. Just use @Inject(forwardRef(() => TestService)), it's can be resolved temporarily.

[adrien2p]

I reproduce will investigate a bit

[muyu66]

Thinks, this error is very important to me because I can remove a lot of "forwardRef".

[adrien2p]

@muyu66 The thing is that actually the index.ts export Test1Service but this one import Test2Service from index.ts which is not exported yet. The only way to avoid that is to import the class from ./test2 or by reversing the order of the exportation in index.ts

export * from './test2';
export * from './test1';

Tell me if i wasn't clear enough :)

[BrunnerLivio]

@adrien2p
That makes sense. Seems to be a general TypeScript issue? Strange I’ve never ran into this problem before, until I’ve used NestJS..

But are you sure this is the problem? I know for example import sorter for VSCode which sort the imports alphabetically and ignores the dependency of each import. That would break the application, but it still seems to work?

[muyu66]

@BrunnerLivio This problem has been bothering me for a long time. My typescript is 2.9.2, Nestjs Core is 5.0.1

[muyu66]

@adrien2p I can understand what you mean, but I didn't modify the code as you suggested, because my project is too big to make this adjustment.

[adrien2p]

@BrunnerLivio i think but maybe it is another thing, the fact is i never had this issue because a never import from an index file since i am in the same directory, alway from another directory.

[muyu66]

The advantage of import from index.ts this is that when I need to change the file name, or file path, I don't need to change all the files that reference it. I just need to modify index.ts.

[adrien2p]

Yes i completely understand i do it as well. Just not in the same directory ^^ Maybe some one else will find a better way to fix that.

And if you change the path, it will not be in this index file anymore but in another one.

[muyu66]

@kamilmysliwiec i want to get your help

[muyu66]

I think of a better way to circumvent this problem. Is to create a hard linux link (ln) to the index.ts, then it's ok that import index_symbolic.ts from test.module.ts

Branch is in resolve-ok, it's passed

[kamilmysliwiec]

Honestly, it sounds like a module resolution issue, instead of anything strictly related to Nest. I saw a bunch of similar issues regarding Angular and I don't think there is a well-known solution available already.

[muyu66]

it's sad

[lock[bot]]

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