Tutorial - User Guide - Intro - FastAPI

• fastAPI refers to HTTP methods as operations. This is because the OpenAPI documentation and schema refer to HTTP methods as operations, so they match the way they call HTTP methods. So, HTTP methods = Operations

• decorators and path decorators

  • That @something syntax in Python is called a "decorator".
  • You put it on top of a function. Like a pretty decorative hat (I guess that's where the term came from).
  • A "decorator" takes the function below and does something with it.
  • In our case, this decorator tells FastAPI that the function below corresponds to the path / with an operation get.
  • It is the "path operation decorator".

• Path decorators:

  • You can also use the other operations:
    • @app.post()
    • @app.put()
    • @app.delete()
  • And the more exotic ones:
    • @app.options()
    • @app.head()
    • @app.patch()
    • @app.trace()

• Define the path operation function

  • This is our "path operation function":
  • path: is /.
  • operation: is get.
  • function: is the function below the "decorator" (below @app.get("/")).

  from fastapi import FastAPI
  
  app = FastAPI()
  
  @app.get("/")
  async def root():
      return {"message": "Hello World"}
  

• This is a Python function.

• It will be called by FastAPI whenever it receives a request to the URL "/" using a GET operation.

• In this case, it is an async function.