🐛 Fix support for `UnionType` (e.g. `str | None`) with Python 3.11 by jonaslb · Pull Request #548 · fastapi/typer

jonaslb · 2023-02-04T02:11:17Z

Potential solution for #533, which already had good details and a proposal for a solution, based on using get_args and get_origin from the typing module instead of the __args__ and __origin__ attributes. So I went and did that.

We also needed to actually handle the UnionType in addition to the Union from before.

Now there was a bit of a headache in terms of writing this in a backwards compatible way. What I've done is place the compatibility code into _compat_utils.py. But let me know if you'd prefer to keep it in main.py.

I also added a single test, just an adapted copy of another one with the x | None syntax. It is conditioned on Python >= 3.10, so it shouldn't fail on older Pythons.

github-actions · 2023-02-04T02:12:27Z

📝 Docs preview for commit 1f9dd82 at: https://63ddbef8955c2d354bae0bbd--typertiangolo.netlify.app

jonaslb · 2023-02-04T02:26:21Z

It looks like mypy behaves differently in the different tests across versions. 3.6, 3.10 and 3.11 are ok, but 3.7, 3.8 and 3.9 are not. That seems confusing. I can maybe look at it another day again, otherwise if someone can see why it happens let me know.

github-actions · 2023-02-06T20:51:22Z

📝 Docs preview for commit 84ad04c at: https://63e1682403f85605237e7c38--typertiangolo.netlify.app

jonaslb · 2023-02-06T20:55:31Z

Failures are down to mypy version I think, it works fine here with latest. I see some errors in other places though (unrelated to my changes).

Also realized there is already another PR for this issue (just references other issue numbers, so I hadn't seen it): #522

Regardless, hope to see either PR merged. Ping @tiangolo

austin-silk · 2023-10-02T15:05:58Z

@tiangolo - can we merge this please?

jonaslb · 2023-10-03T15:32:28Z

Rebased on master and now all is green 👍

Still happy to make adaptations or answer questions.

jonaslb · 2024-03-29T20:35:35Z

@svlandeg I gather that #676 is the preferred solution to the UnionType situation? Should I just close this? Will we ever get anything on the topic merged - ie. what's blocking?

svlandeg · 2024-03-29T23:07:54Z

Hi @jonaslb, we've been going through the backlog of PRs to label them and connect related ones. We've already reviewed, adapted and merged a bunch for last week's releases 0.9.1 through 0.11.0. Open-source maintenance costs time and effort as I hope you can appreciate ;-) Thanks for your contributions (and patience) so far, we'll definitely get to this! It's fine to keep this one open in the meantime.

jonaslb · 2024-03-29T23:42:50Z

Open-source maintenance costs time and effort as I hope you can appreciate ;-)

Of course, and it's great to see that time is now being spent on typer also from the maintainer side ;-) I'm looking forward to engaging about details here if this PR turns out to be the preferred one out of the many submitted on the topic.

…ontype

svlandeg

I confirmed that this behaviour works in 3.10 but broke in 3.11, and the unit test introduced in this PR captures the bug nicely.

I updated this PR so that the changes would be more minimal, using the variables from _typing that were introduced precisely for this type of usage.

This PR now closely resembles #676, though this one captures a few additional cases where __args__ and __origin__ are called directly in the main code. I think it's a good idea to rewrite all of these cases.

As such, I recommend to merge this PR and close #676 (and #739), but I'll leave the final decision with Tiangolo.

lachaib · 2024-06-03T10:09:26Z

Ruff tries to automatically fix these Optional[str] in my parameters and I had to disable it, so I'm really looking forward to seeing this merged and released.

luispsantos · 2024-07-11T11:29:34Z

@tiangolo I understand you have other time commitments and it must be overwhelming, but I would like to have this PR merged whenever possible. I use Ruff with pyupgrade rules like @lachaib and I find the lack of the modern union support a considerable hindrance when using Typer and Ruff together.

tiangolo · 2024-08-17T02:22:35Z

Great! Thank you for your contribution @jonaslb! 🍰

And in particular, thank you for your patience and your kindness. 🤗

Thank you @svlandeg for the great job as always investigating, reviewing, and reporting everything. 🙇

This will be available in Typer 0.12.4, released in the next hours. 🎉

NikosAlexandris · 2024-10-09T12:34:51Z

Does this "fix" not include support for X | Y | Z ?

jonaslb · 2024-10-09T17:33:33Z

This was always a fix for X | None only, i.e. #533. It looks like an error that it was not closed yet (likely because I didn't use the magic words in the description..). #461 looks like the issue for what you seek.

## Description See #163. Typer now supports union types post fastapi/typer#548. It turns out that we have a lower bound on `typer`, i.e., we already support `typer>0.13`, so this PR just fixes the type annotations.

PR Comfy-Org#349 changed type hints from Optional[bool] to bool | None syntax, but typer < 0.12.4 doesn't support PEP 604 union types (X | None). This caused RuntimeError when running comfy CLI with older typer. Changes: - Update typer dependency from >=0.9 to >=0.12.4 - Remove deprecated is_flag parameter from typer.Option() calls (is_flag was deprecated in typer 0.15.0 and never worked properly) Fixes Comfy-Org#355 References: - Typer PEP 604 support: fastapi/typer#548 - is_flag deprecation: fastapi/typer#986

PR Comfy-Org#349 changed type hints from Optional[bool] to bool | None syntax, but typer < 0.12.4 doesn't support PEP 604 union types (X | None). This caused RuntimeError when running comfy CLI with older typer. Changes: - Update typer dependency from >=0.9 to >=0.12.4 - Remove deprecated is_flag parameter from typer.Option() calls (is_flag was deprecated in typer 0.15.0 and never worked properly) Fixes Comfy-Org#355 References: - Typer PEP 604 support: fastapi/typer#548 - is_flag deprecation: fastapi/typer#986 Amp-Thread-ID: https://ampcode.com/threads/T-019bdd23-62ea-732f-9443-5705ebe27a3b Co-authored-by: Amp <amp@ampcode.com>

jonaslb force-pushed the uniontype branch from 1f9dd82 to 84ad04c Compare February 6, 2023 20:49

jonaslb mentioned this pull request Feb 17, 2023

Bump mypy to 1.0.1 & remove Python 3.6 support #556

Closed

jonaslb force-pushed the uniontype branch from 84ad04c to 8fc8d64 Compare October 3, 2023 15:00

Fix UnionType handling as with Union for Optional values

0ddd20c

jonaslb force-pushed the uniontype branch from 8fc8d64 to 0ddd20c Compare October 3, 2023 15:10

svlandeg mentioned this pull request Feb 29, 2024

🐛 Fix support for UnionType with Python 3.11 #676

Closed

svlandeg added feature New feature, enhancement or request types Type hints and type checking p3 labels Mar 1, 2024

svlandeg and others added 6 commits April 11, 2024 13:34

Merge branch 'master' into uniontype (WIP)

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include information from previous compat module into _typing

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🎨 [pre-commit.ci] Auto format from pre-commit.com hooks

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delete file (leftover from merge)

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Merge branch 'uniontype' of https://github.com/jonaslb/typer into uni…

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…ontype

use is_union

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svlandeg approved these changes Apr 11, 2024

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svlandeg added bug Something isn't working p2 and removed feature New feature, enhancement or request p3 labels Apr 11, 2024

svlandeg changed the title ~~Fix #533: UnionType handling as with Union for Optional values~~ 🐛 Fix support for UnionType with Python 3.11 Apr 11, 2024

svlandeg linked an issue Apr 11, 2024 that may be closed by this pull request

PEP 604 Support #348

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7 tasks

This was referenced Apr 11, 2024

PEP 604 Support #348

Closed

TypeError: unsupported operand type(s) for |: 'type' and 'NoneType' #371

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svlandeg linked an issue Apr 11, 2024 that may be closed by this pull request

TypeError: unsupported operand type(s) for |: 'type' and 'NoneType' #371

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7 tasks

svlandeg mentioned this pull request Apr 30, 2024

🔥 Remove unused functionality from _typing.py file #805

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svlandeg mentioned this pull request May 21, 2024

Support for optional as UnionType (Python >= 3.10) #739

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jonaslb mentioned this pull request Jul 12, 2024

🚀 Roadmap #678

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patrick91 approved these changes Jul 18, 2024

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Merge branch 'master' into uniontype

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tiangolo changed the title ~~🐛 Fix support for UnionType with Python 3.11~~ 🐛 Fix support for UnionType (e.g. str | None) with Python 3.11 Aug 17, 2024

tiangolo merged commit 218bf89 into fastapi:master Aug 17, 2024

tiangolo mentioned this pull request Aug 17, 2024

Using some_type | None syntax for type annotations causes error in python 3.11 #533

Closed

7 tasks

cfernhout mentioned this pull request Nov 2, 2024

Support Typer>=0.12.4 to enable support for str | None type hints jeeves-sh/jeeves-shell#55

Merged

iFreilicht mentioned this pull request Apr 1, 2025

"Type not yet supported" when running pyodide-build 0.29.3 pyodide/pyodide-build#163

Closed

agriyakhetarpal mentioned this pull request Apr 1, 2025

Typer>=0.12.4 supports Union types pyodide/pyodide-build#164

Merged

valliu mentioned this pull request Nov 10, 2025

⬆️ Upgrade minimum Typer version to fix CLI commands strawberry-graphql/strawberry#4049

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11 tasks

christian-byrne mentioned this pull request Jan 20, 2026

PR #349 breaks typer compatibility: RuntimeError with 'bool | None' type hints Comfy-Org/comfy-cli#355

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christian-byrne mentioned this pull request Jan 20, 2026

fix: update typer to >=0.12.4 for PEP 604 union type support Comfy-Org/comfy-cli#356

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bigcat88 mentioned this pull request Jan 24, 2026

fix: update typer to >=0.12.5 for PEP 604 union type support Comfy-Org/comfy-cli#357

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