Pip can't resolve dependencies

[dantownsend]

I'm having some trouble installing the following from a requirements file:

jinja2
piccolo[postgres]
piccolo_admin
xpresso
uvicorn

Pip can't resolve the dependencies and gets caught in an endless loop.

It only started today - I noticed because the CI started failing. I can't see anything in the latest Xpresso release which may have caused this.

Do you have any ideas?

[adriangb]

Weird. I have made some changes in the last week, but mostly loosening dependencies. I'll try this and report back.

[dantownsend]

@adriangb Thanks :)

[adriangb]

Worked fine in a colab notebook: https://colab.research.google.com/drive/1yojpO7dArlvlqh6GUay9NedM7AlSpH-g#scrollTo=wWX8WOo8FBzV

Could you post the Python/pip versions, and maybe point me to the failing CI runs and I can take a look at those as well?

Also I assume this works fine without Xpresso?

Edit: I do see an issue with click in the logs for the colab notebook, but xpresso doesn't require click so it looks like it's something else, plus it still installs

[dantownsend]

Here's the failing CI run: https://github.com/piccolo-orm/piccolo/runs/5512366041?check_suite_focus=true

The CI is running Python 3.10.

I tried it locally in a Docker container running Python 3.9 and Pip 21.2.4.

Yeah, it works OK without Xpresso. It could be some other package which doesn't play nice though.

[adriangb]

I was able to reproduce now. I narrowed the issue down to:

piccolo_admin
starlette>=0.19.0

As of accf69a6c6fc3201deb7da94fea2282c1bd84579 Xpresso depends on starlette>=0.19.0 so that we can use https://github.com/encode/starlette/pull/1435. I did this to avoid juggling compatibility; I thought there'd be no reason to install Xpresso along with FastAPI. But it seems like piccolo_admin depends on FastAPI.

So there's two options here:

• Do compatibility stuff in Xpresso to support Starlette >= 0.17.1 (like we did before)
• Remove the direct dependency on FastAPI from Piccolo Admin. FastAPI pins specific Starlette versions, which makes it hard to maintain compatibility with it (I plan not to do this with Xpresso, but I just happened to update to >=0.19.0)

I'll look into the former, I don't think it will be too hard.

[dantownsend]

Thanks for looking into it. I've had problems too in the past with FastAPI version pinning a specific Starlette version.

I can't easily remove FastAPI from Piccolo Admin unfortunately.

I can temporarily disable the integration test, so there's no immediate pressure to get this fixed.

[adriangb]

I think I'll have a fix up in the next 15 min, let me try that before you disable the integration tests 😄

[dantownsend]

Awesome, thanks! 🚀

[adriangb]

All set! Build should be up on PyPi in the next 5 min

[dantownsend]

@adriangb Perfect, thank you!