# Fast API CRUD

```python
from typing import Optional
from fastapi import Body, FastAPI, Response, status, HTTPException
from pydantic import BaseModel
from random import randrange
import psycopg2
from psycopg2.extras import RealDictCursor
import time

app = FastAPI()


class Post(BaseModel):
    title: str
    content: str
    published: bool = True
    rating: Optional[int] = None


while True:
    try:
        conn = psycopg2.connect(host="localhost", database="fastapi",
                                user="postgres", password="admin", cursor_factory=RealDictCursor)
        cursor = conn.cursor()
        print("Database connection successful")
        break
    except Exception as error:
        print("Connection failed")
        print("Error: ", error)
        time.sleep(2)


@app.get("/")
async def root():
    return {"message": "Hello World"}


@app.get("/posts")
def post():
    cursor.execute("SELECT * from posts")
    posts = cursor.fetchall()
    return {"data": posts}


@app.post("/posts", status_code=status.HTTP_201_CREATED)
def create_posts(post: Post):
    cursor.execute("""INSERT INTO posts (title, content, published) VALUES
                   (%s, %s, %s) RETURNING * """,
                   (post.title, post.content, post.published))
    new_post = cursor.fetchone()
    conn.commit()
    return {"data": new_post}


@app.get("/posts/{id}")
def get_post(id: int):
    cursor.execute("""SELECT * from posts WHERE id = %s""", (str(id)))
    post = cursor.fetchone()
    if not post:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND, detail="Post not found")
    return {
        "post_details": post
    }


@app.delete("/posts/{id}", status_code=status.HTTP_204_NO_CONTENT)
def delete_post(id: int):
    cursor.execute("DELETE FROM posts WHERE id = %s RETURNING *", (str(id),))
    deleted_post = cursor.fetchone()
    conn.commit()
    if deleted_post == None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND, detail=f"{id} not found")
    return Response(status_code=status.HTTP_204_NO_CONTENT)


@app.put("/posts/{id}", status_code=status.HTTP_201_CREATED)
def update_post(id: int, post: Post):
    cursor.execute("""UPDATE posts SET title = %s, content = %s, published = %s
                   WHERE id = %s RETURNING *""", (post.title, post.content,
                                                  post.published, str(id)))
    updated_post = cursor.fetchone()
    conn.commit()
    if updated_post == None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND, detail=f"{id} not found")
    return {"data": updated_post}

```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://gautamnaik1994.gitbook.io/snippets/backend/fast-api-crud.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.