swc: Cannot access before initialization error in NestJs

Describe the bug

I’m using swc in a NestJs project and i’m facing the following issue when i run my unit test with jest:

ReferenceError: Cannot access 'DocumentEntity' before initialization

      10 |
      11 | @Entity('documents')
    > 12 | export class DocumentEntity extends EntityObj {
         |              ^
      13 |   @PrimaryGeneratedColumn()
      14 |   id: string;
      15 |

      at Object.DocumentEntity (features/documents/document.entity.ts:12:14)
      at Object.<anonymous> (features/documents/data/document-data.entity.ts:16:14)
      at Object.<anonymous> (features/documents/document.entity.ts:12:29)
      at Object.<anonymous> (features/resources/resource.entity.ts:13:25)
      at Object.<anonymous> (features/resources/resources-db.store.ts:10:25)
      at Object.<anonymous> (features/resources/resources-db.store.spec.ts:5:27)

I think the error is caused by the automapper library which i use in the document-data.entity.ts:

Input code

@Entity('documents-data')
export class DocumentDataEntity {
  @PrimaryColumn()
  @AutoMap()
  key: string;

  @PrimaryColumn({ nullable: false })
  documentId?: string;

  @AutoMap(() => DocumentEntity) // Think error comes from here
  document?: DocumentEntity;
}

Config

{
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": false,
      "decorators": true,
      "dynamicImport": true
    },
    "target": "es2021",
    "transform": {
      "legacyDecorator": true,
      "decoratorMetadata": true
    }
  },
  "module": {
    "type": "commonjs",
    "noInterop": false
  }
}

FYI, it works with the swc config "target": "es5" but then i’ve got code coverage issues

Playground link

No response

Expected behavior

I’m expecting the test to run correctly

Actual behavior

No response

Version

1.13.19

Additional context

No response

About this issue

Original URL
State: closed
Created 2 years ago
Reactions: 10
Comments: 15 (1 by maintainers)

Most upvoted comments

I am getting the same error after upgrading swc. I am using ts-node with swc, via my tsconfig.json

  "ts-node": {
    "swc": true
  },

This error is happening pretty much everywhere there is a typescript reference to a class type. For example, in my entity class, the fields will reference typescript types of other entity classes.

It seems to be a problem with the loader not understanding that these are merely type references and not instances of the class object. I can remove the error by the following, but I have to do it all throughout my code base!

Create a trivial typescript type

type Type<T> = T;

Then change all my class type references from Foo to Type<Foo>. For example, if I have a field such as

todos: Todo[];

then it becomes

todos: Type<Todo>[];

When I do this, the circular dependency is resolved. It seems to force the class reference to be treated as just a type, rather than an actual class object instance. Very strange,

dustin-rcg on Dec 2, 2022

This issue has been automatically closed because it received no activity for a month and had no reproduction to investigate. If you think this was closed by accident, please leave a comment. If you are running into a similar issue, please open a new issue with a reproduction. Thank you.

swc-bot on Apr 1, 2023