BUG/ENH: Translate CSS border properties for Styler.to_excel

[tehunter]

• checks an item on BUG: Styler.to_excel does not export styles and formats correctly #42276 ("Border styles bug")
• tests added / passed
• Ensure all linting tests pass, see here for how to run them
• whatsnew entry

[pep8speaks]

Hello @tehunter! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2022-02-10 13:27:41 UTC

[attack68]

can you also look to add a roundtrip test in pandas/tests/io/excel/test_style.py

[tehunter]

Any idea what could be causing the failure? It's something related to filesystems in test_arrowparquet_options, which I haven't touched.

[attack68]

Looking really good, especially the style round trip. Just one or two comments for optimisation.

[attack68]

can you show a test that exerices this at a high level as well

Its difficult to test this since you have to write to excel and then read that the file rendered correctly.

The round trip tests I requested in test_style.py now do this: explicitly they check that:

a) The styled dataframe (with a border) is different to the unstyled dataframe (without border)
b) that the excel file created is read in correctly by openpyxl and has the border styles as expected.

[tehunter]

needs a whats new 1.5.0, (maybe 1.4.1 if it can be backported).

Do I write the entry or does a maintainer do that? I propose 2 entries along the lines of:

• Bug Fix: Fixed bug in CSSToExcelConverter leading to TypeError when border color provided without border style for xlsxwriter engine (GH42276)
• Enhancement / Styler Enhancements: Added the ability to render border and border-{side} CSS properties in Excel (GH42276)

[jreback]

@tehunter u add them

[jreback]

looks fine (but before i resolved i think the doc-build was failing) so let's check that.

[jreback]

yeah these are failing: https://github.com/pandas-dev/pandas/runs/4841791532?check_suite_focus=true

[tehunter]

@github-actions pre-commit

[attack68]

@tehunter if you get a chance to merge with main, i can take a look at the CI errors you are getting

[jreback]

just put this in the I/O section

[jreback]

thanks @tehunter