[Question] Access app instance from Router files

In the router files I need access to the app instance to be able to use methods like url_path_for. However, since in main.py the routers are imported before the app is created, I cannot import the app there (circular import). Also in the validators for the models I would like to have access to the app.

I see two solutions:

• import the app within the router function (during request handling)
• Add a reference to the router objects to the app To avoid problems with linting the __import__ function could be used instead of the import statement.

Are there better (standard) solutions to solve this issue?

[falkben]

One thing you can do is access the app on the request object.

request.app.url_path_for("logout")

This works fine in a simple case at least with the following structure:

├── __init__.py
├── main.py
├── routerA.py
└── routerB.py

Where main.py is:

from fastapi import FastAPI

from experiments.multi_file_app.routerA import router as routerA
from experiments.multi_file_app.routerB import router as routerB

app = FastAPI()

app.include_router(routerB)
app.include_router(routerA)

if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app)

I know this piece isn’t covered in the “Bigger Applications” but still worth going through: https://fastapi.tiangolo.com/tutorial/bigger-applications/

[github-actions[bot]]

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