Nest: Incorrect Controller initialization when using "import as" on same controller type from different folders

[Masterrg]

I'm submitting a...

[ ] Regression 
[X] Bug report
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

I've got two controllers with the same name (i.e. MainController) in two different folders:
Controller 1: sectionOne/MainController
Controller 2: sectionTwo/MainController

When I am trying to initialize both controllers within a module by using "import as", only one controller gets loaded.

Expected behavior

Both controllers should get initialized.

Minimal reproduction of the problem with instructions

nestjs-bug.zip

npm install
npm start
Result: Only one controller gets initialized.

What is the motivation / use case for changing the behavior?

Wouldn't be that bad to be able to reuse controllernames/types from different paths.

Environment

Nest version: ^5.0.1


For Tooling issues:
- Node version: 8.9.4
- Platform:  Windows

Others:

[kamilmysliwiec]

Why would you like to use the exact same controller twice in a single module?

[natqe]

@kamilmysliwiec his meaning is the exact same name, not the controller himself.

[kamilmysliwiec]

Isn't is quite confusing when you have two classes with the same name?

[Masterrg]

Not really, especially if you take the whole import path / namespace into consideration.

For example the controller of webhooksgithubmain.controller.ts could do something different like webhooksbitbucketmain.controller.ts - as they are two different things (especially in terms of inheritance) and possibly do different things.

Long story short: Just taking the name of a class/controller into consideration doesn't feel like the correct way in terms of oop. Maybe I am a bit too spoiled by Java or C# or even PHP but overall... it's a bit smelly if "duplicate" class names in different paths/namespaces result in such a conflict.

[kamilmysliwiec]

Anyway, as far as I know, the same name may cause issues only inside the same module. And putting the classes with the same name into one module is definitely considered as a bad practice. In your ^ example, you could split github and bitbucket directories into two different modules and it'll work fine.

[Masterrg]

I wouldn't agree that it's a bad practice as it's clear in terms of the import path of the specific class and by using import as - using a class A\B\C\MainClass and D\E\F\MainClass doesn't mean that both "MainClasses" got the same type.

It's a similar situation with the github and bitbucket example from above: I would have a webhooks module which references to the specific controllers, as creating a module just for i.e. 2 routes per controller without a lot business logic is not really worth it and may seems to be a bit overloaded.

Nevertheless, I totally got your point.

Suggestion in case the behaviour won't change in future:

• Maybe extend the documentation and add a part that you only use a "controllername" once in a module
• Maybe throw an exception in such a case as it's hard to debug if a controller fails silently/doesn't get initialized without any extra information

We experienced this issue after a bigger refactoring session, and all out of sudden some routes weren't available anymore. Luckily we found the issue in a relatively short amount of time - nevertheless you get a small heart attack if things stop working out of sudden without proper information.

[kamilmysliwiec]

Maybe throw an exception in such a case as it's hard to debug if a controller fails silently/doesn't get initialized without any extra information

We shall at least show a proper warning message. Thanks for reporting, it will be available soon 🙂

[xavi-dev]

You said that this is not a problem when using different modules https://github.com/nestjs/nest/issues/789#issuecomment-398290390 but is still happening to me.

https://github.com/nestjs/nest/files/3060552/same.zip

[imagine10255]

Does this problem still exist? This problem is the same as currently using 7.0.7.
Is there a way to use namespaces like php laravel?

[xxstop]

I met, relationship (in services):

A -> B -> B (parent)
B

Parent B cannot inject child B,
What is the current quick solution?

[stevenhair]

@xxstop There are two quick fix solutions that I can think of:

1. If you control one of the classes, just rename it
2. If you don't control the classes (if they come from third-party libraries, for example), you can extend them and then use your subclass (note that you will need to use the subclass everywhere) - e.g.:
   ```typescript
   import { Client } from 'some-package';

export class MyWrappedClient extends Client {}
```

Neither are really ideal, although it's probably a bad idea to have two classes with the same name in a single project. I inherited a non-Nest project like that and it makes working on the project a bit more difficult - I find myself opening the wrong file a lot.