How to specify version in only one place when using pyproject.toml?

Question

My package version is defined in two places:

__version__ = 1.2.3 in mypackage/__init__.py
version = "1.2.3" in pyproject.toml (I am using Poetry)

I have to update both whenever I bump the version which is annoying and not DRY. Is there a way to make Python read the version from the TOML, or to make the TOML read the version from Python?

You sniffed something fishy and you were right. Why would you need another place to track your project's metadata if you already use `pyproject.toml`? — z33k, Dec 01 '21 at 14:31

finswimmer · Accepted Answer · 2022-01-27T18:46:08.973

50

After you have installed your project - either in editable mode by poetry install or from the wheel - you can access several metadata via importlib.metadata (importlib_metadata for python < 3.8).

So keep the version only in the pyproject.toml and use this in your python code:

import importlib.metadata

__version__ = importlib.metadata.version("mypackage")

edited Jan 27 '22 at 18:46

answered Apr 14 '21 at 18:19

finswimmer

10,896
3
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1

Thanks! Out of curiosity, where would I find this information in the docs? https://python-poetry.org/docs/pyproject/#version is quite terse. – Haterind Apr 14 '21 at 19:02
1

This works quite well until it runs in a GitLab pipeline. Any clues on how to do this *without* the ability to install the package? – Jonathan Belden Mar 07 '23 at 16:48

Alwin · Answer 2 · 2022-09-08T14:26:40.300

12

This code worked for me:

import importlib.metadata

__version__ = importlib_metadata.version(__package__ or __name__)

However, this only works if the package is already installed using pip or poetry.

On newer version (dot instead of underscore):

__version__ = importlib.metadata.version(__package__ or __name__)

edited Sep 08 '22 at 14:26

answered Feb 15 '22 at 12:56

Alwin

786
9
19

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would this work for editable installs? from what i am seeing when editable install and change version in pyproject.toml wouldnt be reflected? – kamster Nov 15 '22 at 19:42

score 5 · Answer 3 · edited Jul 06 '23 at 13:04

Maybe overly complicated, but in order to not confuse an installed version of a package with an instance lingering around locally I use this code:


from contextlib import suppress
import importlib.metadata
from pathlib import Path


def extract_version() -> str:
    """Returns either the version of installed package or the one
    found in nearby pyproject.toml"""
    with suppress(FileNotFoundError, StopIteration):
        with open((root_dir := Path(__file__).parent.parent)
                  / "pyproject.toml", encoding="utf-8") as pyproject_toml:
            version = (
                next(line for line in pyproject_toml if line.startswith("version"))
                .split("=")[1]
                .strip("'\"\n ")
            )
            return f"{version}-dev (at {root_dir})"
    return importlib.metadata.version(__package__
                                      or __name__.split(".", maxsplit=1)[0])

__version__ = extract_version()

Giving me either 1.2.23 for installed packages or something like 1.3.42-dev (at /project/location)

This needs something `import`ed right? – Mausy5043 Jun 07 '23 at 07:05 — Mausy5043, Jun 07 '23 at 07:05
`from contexlib import suppress` and `importlib` – frans Jun 08 '23 at 10:39 — frans, Jun 08 '23 at 10:39

score 1 · Answer 4 · answered Jul 14 '23 at 23:05

All of the current answers address the issue of getting the version after install. However, as Jonathan Belden points out in a comment on @finswimmer's answer, these methods break in CI pipelines and the like when the package isn't installed. In keeping with @z33k's comment on the question, one solution would be to read the value from pyproject.toml.

With poetry as your package manager, another solution would be to use the poetry-bumpversion plugin to manage version bumps using poetry's version command. For example, say you have a package called widget, with __version__ defined in widget/__init__.py, with the same value as pyproject.toml has for version. With the poetry-bumpversion plugin, you would add

[tool.poetry_bumpversion.file."widget/__init__.py"]

to pyproject.toml, then

% poetry version patch
Bumping version from 0.7.9 to 0.7.10
poetry_bumpversion: processed file widget/__init__.py

% git diff -U0
diff --git a/widget/__init__.py b/widget/__init__.py
index 18c7cbf..9ff9982 100644
--- a/widget/__init__.py
+++ b/widget/__init__.py
@@ -1 +1 @@
-__version__ = "0.7.9"
+__version__ = "0.7.10"
diff --git a/pyproject.toml b/pyproject.toml
index 1b86c6e..5de1ce1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3 +3 @@ name = "widget"
-version = "0.7.9"
+version = "0.7.10"
@@ -55,0 +56,2 @@ tox = "^4.6.4"
+[tool.poetry_bumpversion.file."widget/__init__.py"]
+

How to specify version in only one place when using pyproject.toml?

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