Resolver instance (this) is not available in subscription filter/resolver methods

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 have:

(...)
export class CommentResolver {
  constructor(
    private readonly commentsDataLoader: CommentsDataLoader, // request-scoped
    private readonly commentService: CommentService,
    private readonly pubSub: PubSubService,
    (...)
  ) {}

  (...)

  @Subscription(returns => CommentType, {
    filter(this: CommentResolver, payload, variables) {
      // filter by the correct parent
      return this.commentService.belongsToParent({
        commentId: payload.newComment,
        parentId: variables.parentId,
      });
    },
    resolve(this: CommentResolver, payload) {
      return this.commentService.findOneById(payload.newComment);
    },
  })
  async newComment(
    @Args('parentId') parentId: string,
  ): Promise<AsyncIterator<CommentType>> {
    return this.pubSub.asyncIterator<CommentEntity>('newComment');
  }

 (...)

(newComment is only an ID string in the pubSub payload)

I am getting this response from the subscription:

{
  "error": {
    "name": "TypeError",
    "message": "Cannot read property 'belongsToParent' of undefined"
  }
}

Expected behavior

commentService should be instantiated inside the filter method of the @Subscriptiondecorator. It is when used in a resolver method.

Minimal reproduction of the problem with instructions

ˆˆˆ

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

It’s not working as described in the docs.

Environment

Nest version: 6.8.2
"@nestjs/common": "6.8.2",
"@nestjs/core": "6.8.2",
"@nestjs/graphql": "^6.5.3",
"@nestjs/jwt": "^6.1.1",
"@nestjs/passport": "^6.1.0",
"@nestjs/platform-express": "6.8.2",
"@nestjs/typeorm": "^6.2.0",

 
For Tooling issues:
- Node version: 10.15.0  
- Platform:  Mac 

[kamilmysliwiec]

Please, provide a minimal repository which reproduces your issue.

[lock[bot]]

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