def get_article(article_id: int, repo: AbstractRepository):
article = repo.get_article(article_id)
if article is None:
raise NonExistentArticleException
return article_to_dict(article)
def get_comments_for_article(article_id, repo: AbstractRepository):
article = repo.get_article(article_id)
if article is None:
raise NonExistentArticleException
return comments_to_dict(article.comments)
def add_comment(article_id: int, comment_text: str, username: str,
repo: AbstractRepository):
# Check that the article exists.
article = repo.get_article(article_id)
if article is None:
raise NonExistentArticleException
user = repo.get_user(username)
if user is None:
raise UnknownUserException
# Create comment.
comment = make_comment(comment_text, user, article)
# Update the repository.
repo.add_comment(comment)
