transformer.ts

  getPostAndAuthorData = createTransformer((postId: string) => {
    const post = this.getPost(postId);
    if (!post) return undefined;
    const author = this.getAuthor(post.authorId);
    if (!author) return undefined;
    return {
      post,
      author
    }
  });


// in component autorun
 this.content = this.postService.getPostAndAuthorData(postId)