forum-app/backend/forum.py

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Post:
    """Post is a single forum post or reply"""
    id: int
    thread_id: int
    author: str
    title: str
    content: str

    def __init__(self, id, thread_id, author, title, content):
        self.id = id
        self.thread_id = thread_id
        self.author = author
        self.title = title
        self.content = content


class PostCreate(BaseModel):
    """Used when creating posts and replies"""
    author: str = 'anon'
    title: str
    content: str


class Thread:
    """Thread is a collection of a post and its replies"""
    id: int
    author: str
    title: str
    closed: bool

    def __init__(self, id, author, title, closed=False):
        self.id = id
        self.author = author
        self.title = title
        self.closed = closed


POSTS = []
THREADS = []


@app.get("/")
async def get_threads():
    return THREADS


@app.post("/post")
async def create_post(data: PostCreate):
    id = len(POSTS) + 1
    author = data.author
    title = data.title
    content = data.content

    # Create thread
    thread = Thread(
        id=id,
        author=author,
        title=title
    )
    THREADS.append(thread)

    # Create post
    post = Post(
        id=id,
        thread_id=id,
        author=author,
        title=title,
        content=content
    )
    POSTS.append(post)

    return post


@app.get("/{thread_id}")
async def get_thread(thread_id: int):
    result = []
    for post in POSTS:
        if post.thread_id == thread_id:
            result.append(post)

    if len(result) == 0:
        return {'error': 'could not find parent thread'}

    return result


@app.post("/{thread_id}/post")
async def reply_to_post(thread_id: int, data: PostCreate):
    parent = None
    for thread in THREADS:
        if thread.id == thread_id:
            parent = thread

    if parent is None:
        return {'error': 'could not find parent thread'}

    id = len(POSTS) + 1
    author = data.author
    title = data.title
    content = data.content

    # Create post
    post = Post(
        id=id,
        thread_id=parent.id,
        author=author,
        title=title,
        content=content
    )
    POSTS.append(post)

    return post