Type safety between resolver decorator and resolver return value

[miloofcroton]

I'm relatively new to decorators and type-graphql, but not typescript or graphql in general.

Correct code:

  @Query(
    () => [Post],
    { description: "Get all the posts" }
  )
  async getPosts(): Promise<Post[]> {
    return await this.items;
  }

No type error #1:

  @Query(
    () => Post,
    { description: "Get all the posts" }
  )
  async getPosts(): Promise<Post[]> {
    return await this.items;
  }

No type error #2:

  @Query(
    () => [Post],
    { description: "Get all the posts" }
  )
  async getPosts(): Promise<Post> {
    return await this.items.pop(); // I had to modify this code so it behaves with the asserted type Promise<Post> , which is expected
  }

This is a field in a class for all Post resolvers. It seems there's no connection between the @Query decorator's first param (a function with a [Post] return) and the return value of the function async getPosts(), which is Promise<Post[]>. If I change the value from Post[] to Post, no type error pops up.

I'm not sure if I'm using the library incorrectly or if the library just doesn't support fully type-safe resolvers with one source of truth. Can anyone shed light on this?

[MichalLytek]

See https://github.com/borremosch/eslint-plugin-type-graphql