Hello world to Backend

API Execution:

To run the API file, use the following command:

    uvicorn <file_name>:app --reload

Request Methods:

GET: /books/ {path parameter}
QUERY: /books/?category=science (query parameter)
POST: Create new data
PUT: Update existing data
DELETE: Remove data

Note: When using the GET method, the query parameter should follow the endpoint.

Validation Values:

Using in atribute:

class BookRequest(BaseModel):
  id: Optional[int] = Field(title='id is not needed')
  title: str = Field(min_length=3)
  author: str = Field(min_length=1)
  description: str = Field(min_length=1, max_length=100)
  rating: int = Field(gt=0, lt=6)
  published_date: int = Field(gt=2000)

GET: Path method

async def get_validation(param: int = Path(lt=2)):

QUERY: Query method

async def get_validation(param: int = Query(lt=2)):

Status Codes:

2xx series - Standard Response of a Successful Request:

200 - OK: Commonly used for GET requests when data is returned.
202 - Created: Successful request for creating new data. Commonly used for POST requests.
204 - No Content: Successful request, but no content is returned (null). Example: PUT request.

4xx series - Client Errors:

400 - Bad Request: Unable to process the request due to a client error. Commonly used for invalid methods, such as an incorrect HTTP method.
401 - Unauthorized: Authentication failed or the user does not have permission to access.
404 - Not Found: The requested resource or endpoint cannot be found.
422 - Unprocessable Entity: Invalid constraints from the client.

5xx series - Server Status Codes:

500 - Internal Server Error: Occurs when an unexpected issue happens on the server.

Raise exeption

from fastapi imort HTTPExeption

@app.get(....)
async def somethint():
  # your code
  ...
  raise HTTPExeption(status_code="404", detail="your warn")

Explicit Status code

from starlette import status

@app.get("/books", status_code=status.HTPP_200_OK) 
@app.get("/books/create_book", status_code=status.HTPP_202_CREATED) 
@app.get("/books", status_code=status.HTPP_204_NO_CONTENT)

Database with API

SQL Alchemy

This a modul in python helping us for connect and control with database easily through a injection code. This following code for create a simple setup for sqlalchemy

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base

SQLALCHEMY_DATABASE_URL = "sqlite:///./todos.db" #

engine = create_engine(SQLALCHEMY_DATABASE_URL, connect_args={'check_same_thread': False}) # connect with database through URL


SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine) # UI to interact with Database

Base = declarative_base() # class stand for table

In another file, just import Base and it's will create a file with ext == .db, after this run commandline:

sqlite3 todos.db

khoa16122004/FastAPI-Practice