"Override settings from command line" feature errors when no overrides given

[jwodder]

• I have read the Filing Issues and subsequent “How to Get Help” sections of the documentation.
• I have searched the issues (including closed ones) and believe that this is not a duplicate.
• OS version and name: macOS 10.13.6
• Python version: 3.8.3
• Pelican version: master branch, commit 74692a3
• Theme: simple
• Configuration: https://gist.github.com/jwodder/9e70dce1ba8e3a24742a8870e9067fee

Issue

After this commit was made, trying to build with the latest development version of Pelican errors out. Running pelican -s pelicanconf.py --debug outputs the following:

DEBUG: Pelican version: 4.2.0
DEBUG: Python version: 3.8.3 
CRITICAL: 'NoneType' object has no attribute 'items'
Traceback (most recent call last):
  File "/Users/jwodder/work/dev/kbits/.nox/build/bin/pelican", line 8, in <module>  
    sys.exit(main())
  File "/Users/jwodder/work/dev/kbits/.nox/build/lib/python3.8/site-packages/pelican/__init__.py", line 486, in main
    pelican, settings = get_instance(args)
  File "/Users/jwodder/work/dev/kbits/.nox/build/lib/python3.8/site-packages/pelican/__init__.py", line 395, in get_instance
    settings = read_settings(config_file, override=get_config(args))
  File "/Users/jwodder/work/dev/kbits/.nox/build/lib/python3.8/site-packages/pelican/__init__.py", line 383, in get_config
    config.update(coerce_overrides(args.overrides))
  File "/Users/jwodder/work/dev/kbits/.nox/build/lib/python3.8/site-packages/pelican/settings.py", line 667, in coerce_overrides
    for k, v in overrides.items():
AttributeError: 'NoneType' object has no attribute 'items'

I believe the problem is that args.overrides is None when no --extra-settings arguments are given on the command line. Attempting to test this theory by adding --extra-settings AUTHOR=Me made pelican fail with a different error:

DEBUG: Pelican version: 4.2.0
DEBUG: Python version: 3.8.3
CRITICAL: 'AUTHOR'
Traceback (most recent call last):
  File "/Users/jwodder/work/dev/kbits/.nox/build/bin/pelican", line 8, in <module>
    sys.exit(main())
  File "/Users/jwodder/work/dev/kbits/.nox/build/lib/python3.8/site-packages/pelican/__init__.py", line 486, in main
    pelican, settings = get_instance(args)
  File "/Users/jwodder/work/dev/kbits/.nox/build/lib/python3.8/site-packages/pelican/__init__.py", line 395, in get_instance
    settings = read_settings(config_file, override=get_config(args))
  File "/Users/jwodder/work/dev/kbits/.nox/build/lib/python3.8/site-packages/pelican/__init__.py", line 383, in get_config
    config.update(coerce_overrides(args.overrides))
  File "/Users/jwodder/work/dev/kbits/.nox/build/lib/python3.8/site-packages/pelican/settings.py", line 671, in coerce_overrides
    setting_type = type(DEFAULT_CONFIG[k])
KeyError: 'AUTHOR'

[justinmayer]

@sabaini : Any thoughts on this?

[avaris]

My bad. Missed some obvious issues in the review. After a quick look, following might be enough to fix. Here:

pelican/pelican/settings.py

Lines 664 to 665 in 74692a3

	def coerce_overrides(overrides):
	coerced = {}

this addition

def coerce_overrides(overrides):
    if overrides is None:
        return {}
    coerced = {}

And this:

pelican/pelican/settings.py

Line 668 in 74692a3

if k not in overrides:

changed to:

        if k not in DEFAULT_CONFIG:

PS: -e AUTHOR=Me will issue a warning and will be ignored, since it's not in DEFAULT_CONFIG. Unfortunately, that's the limitation of implementation.

[justinmayer]

Thanks for reporting this, @jwodder. The fix proposed by @avaris seems to resolve the problem in my (admittedly limited) testing, so I just pushed a commit including those changes: 45c5cb9 Thank you, @avaris! 👏

Another thing I noticed is that capitalized Boolean values, such as the one I provided as an example in the docs, yield this error:

CRITICAL: Expecting value: line 1 column 1 (char 0)

Lower-case Boolean values seem to work fine. For the moment, I changed the example in the docs to use a lower-case Boolean value. But it would be nice to fix this properly and help users avoid running into critical errors.

[justinmayer]

Changing from:

types_to_cast = {int, str}

… to:

types_to_cast = {int, str, bool}

… seems to fix the aforementioned error and works with both lowercase and uppercase Boolean values. Anyone see any potentially unforeseen problems with this fix?

[justinmayer]

I went ahead and made the above-mentioned Boolean-related change. Despite tests passing locally, GitHub CI is reporting some kind of internal error that I don't understand and that I suspect is unrelated to the small change in the last commit. Maybe related to parallel testing via pytest-xdist, or maybe GitHub CI is just having a bad day. Who knows.

@jwodder: Can you test latest master and see whether the first item you reported here has been resolved?

[jwodder]

@justinmayer The problem has been resolved.