Access a variable or function in main.py from another file.

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Example Code

no code :(

Description

I want to get access to a variable or function which is in main.py from another file (a file which has routers). for example I create a variable (request rate limiter) in main.py and pass it to fastapi app. then I want to use it as decorator when defining routes but my routes are not in main.py so I have to pass to router file to use it while creating routes. I used this example (rate limiter) to just explain my problem and there might be better ways for setting up this and may no need for passing variable like this. Thank you in advance

Operating System

Linux

Operating System Details

No response

FastAPI Version

0.65.2

Python Version

3.8.6

Additional Context

No response

[jgould22]

If you place __init__.py files in the correct folders you can simply import your function with something like from <project_name>.main import rate_limit_decorator

[ifamirhasan]

You can do it, create an dependencies.py (or any name you want), import it in your main (imports are made on the top of the file, and you can follow what @jgould22 said or search about “python import variable from another file” on Google) and use it in the line after the import.

I will try to make a generic example: (basic from the first link I send, but mixed with first steps)

The structure of files would be like that: (init.py is a blank file)

├── app
│   ├── __init__.py
│   ├── main.py
│   └── dependencies.py

Your main file:

from fastapi import FastAPI
# I think the standard name in Python would be rate_limiter, if it's a function and RateLimiter if it a class
from ..dependencies import rateLimiter  

app = FastAPI()


# Use it where you need
@app.get("/")
@rateLimiter  # Your decorator
async def root():
    return {"message": "Hello World"}

If I understood correctly, it is what you want, but without code and directory structure, is hard to say and I’m not an expert.

Thanks for your answer and help. I understand what you are saying but the rate limiter is just an example. In my case it is different and I have to do few things with that variable before app starts and I can’t create it for each request. but fortunately I figured it out, as I said in my last comment I have to create the variable in a file (config.py) and I can import it every where and use it globally. Again thanks for your help.