flake8-datetime-import

flake8-datetime-import is an opinionated plugin which aims to reduce confusing or inconsistent usage of Python's datetime module. It checks that datetime and time are imported as modules and aliased like:

import datetime as dt
import time as tm

Installation

pip install flake8-datetime-import

flake8 codes

Code	Description
DTI100	from datetime import ... is not allowed. datetime must be imported as a module.
DTI101	datetime imported without aliasing as dt. Expected import datetime as dt.
DTI200	from time import ... is not allowed. time must be imported as a module.
DTI201	time imported without aliasing as tm. Expected import time as tm.

Rationale

datetime and time are confusing when encountered in code. Are they modules? Are they classes or functions?

# Bad
import datetime
from datetime import datetime, time, timezone

import time
from time import time, timezone

Consistently importing and aliasing the datetime and time modules helps prevent this ambiguity.

# Good
import datetime as dt
import time as tm

dt.datetime.now()
tm.time()

Importing and namespacing datetime prevents other naming collisions, such as Django's django.utils.timezone:

import datetime as dt

from django.utils import timezone

dt.timezone.utc
timezone.now()

This plugin was inspired by:

• A talk by @brandon-rhodes at PyCon Canada in which he mentioned this importing strategy
• Code review fatigue

Other notable mentions of this importing strategy:

• https://adamj.eu/tech/2019/09/12/how-i-import-pythons-datetime-module/

pre-commit

To use with pre-commit, add flake8-datetime-import as an additional dependency to flake8.

# .pre-commit-config.yml

-   repo: https://github.com/pycqa/flake8
    rev: 7.3.0
    hooks:
    -   id: flake8
        additional_dependencies: [
          flake8-datetime-import,
        ]

Using ruff instead

If you use ruff, you can enforce the same convention without this plugin via flake8-import-conventions. Ban from datetime import ... / from time import ... and require the dt and tm aliases:

# pyproject.toml

[tool.ruff.lint]
select = ["ICN"]

[tool.ruff.lint.flake8-import-conventions]
banned-from = [
  "datetime",  # Use `import datetime as dt`, not `from datetime import ...`
  "time",      # Use `import time as tm`, not `from time import ...`
]

[tool.ruff.lint.flake8-import-conventions.extend-aliases]
datetime = "dt"
time = "tm"