Flask teardown request equivalent in Fastapi

Question

I am building a rest api with fastapi. I implemented the data layer separately from the fastapi application meaning I do not have direct access to the database session in my fastapi application.

I have access to the storage object which have method like close_session which allow me to close the current session.

Is there a equivalent of flask teardown_request in fastapi?

Flask Implementation

from models import storage
.....
.....

@app.teardown_request
def close_session(exception=None):
    storage.close_session()

I have looked at fastapi on_event('shutdown') and on_event('startup'). These two only runs when the application is shutting down or starting up.

Asked By: coolboimax

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Source

Answer 1

use fastapi middleware

A "middleware" is a function that works with every request before it is processed by any specific path operation. And also with every response before returning it.

It takes each request that comes to your application.
It can then do something to that request or run any needed code.
Then it passes the request to be processed by the rest of the application (by some path operation).
It then takes the response generated by the application (by some path operation).
It can do something to that response or run any needed code.
Then it returns the response.

Example:

import time

from fastapi import FastAPI, Request

app = FastAPI()


@app.middleware("http")
async def add_process_time_header(request: Request, call_next):
    # do things before the request
    response = await call_next(request)
    # do things after the request
    return response

Answered By: anjaneyulubatta505

Answer 2

We can do this by using dependency.

credit to williamjemir: Click here to read the github discussion

from fastapi import FastAPI, Depends                           
from models import storage
                                                                                                                   
async def close_session() -> None:  
  """Close current after every request."""
  print('Closing current session')
  yield                         
  storage.close()  
  print('db session closed.')

app = FastAPI(dependencies=[Depends(close_session)])                        
                                                                                                                                          
@app.get('/')                                                        
def home():                                                          
   return "Hello World"                                             
                                                                    
if __name__ == '__main__':                                           
  import uvicorn  
  uvicorn.run(app)

Answered By: Maxwell D. Dorliea

Flask teardown request equivalent in Fastapi

Question:

Answers:

use fastapi middleware