gh-138005: Document that CSV `skipinitialspace=True` and `delimiter=' '` require quotation for empty fields #138006

maurycy · 2025-08-20T19:04:20Z

Please see for the code:

Lines 1253 to 1267 in 7dc42b6

    
           if (!field_len && dialect->delimiter == ' ' && dialect->skipinitialspace) { 
        
               if (dialect->quoting == QUOTE_NONE || 
        
                   (field == NULL && 
        
                    (dialect->quoting == QUOTE_STRINGS || 
        
                     dialect->quoting == QUOTE_NOTNULL))) 
        
               { 
        
                   PyErr_Format(self->error_obj, 
        
                                "empty field must be quoted if delimiter is a space " 
        
                                "and skipinitialspace is true"); 
        
                   return 0; 
        
               } 
        
               quoted = 1; 
        
           } 
        
           rec_len = join_append_data(self, field_kind, field_data, field_len, 
        
                                      &quoted, 0);

Please see the test:

https://github.com/python/cpython/pull/115721/files#diff-dd5e5efc1566b1c1dc988769a04cc403d2416c8af5bf4785bec235d02a780813R352-R354

The behavior is intentional since gh-115721, so the only sensible route is to update the docs.

Issue: Document that CSV skipinitialspace=True and delimiter=' ' require quotation for empty fields #138005

📚 Documentation preview 📚: https://cpython-previews--138006.org.readthedocs.build/

serhiy-storchaka

I think this is too verbose. The note takes up a lot of space and attracts a disproportionate amount of attention. Most users will never encounter this, and if they do, this behavior is expected and therefore does not require any special explanation.

Could you please limit yourself to one short sentence? That such CSV files cannot contain empty fields.

maurycy · 2025-08-21T10:54:10Z

I think this is too verbose. The note takes up a lot of space and attracts a disproportionate amount of attention. Most users will never encounter this, and if they do, this behavior is expected and therefore does not require any special explanation.

Could you please limit yourself to one short sentence? That such CSV files cannot contain empty fields.

Thank you for taking a look. Made it much shorter:

https://github.com/python/cpython/pull/138006/files#diff-863b8cdc270a710deec9ffcf11f82fe2547cd96e8d935e37361b431a5accd3f3R470-R471

serhiy-storchaka

LGTM. 👍

sharktide

LGTM
And thanks for fixing the typo :)

miss-islington-app · 2025-09-11T15:11:37Z

Thanks @maurycy for the PR, and @hugovk for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

…iter=' '` require quotation for empty fields (pythonGH-138006) (cherry picked from commit e0f54a6) Co-authored-by: Maurycy Pawłowski-Wieroński <[email protected]>

bedevere-app · 2025-09-11T15:11:51Z

GH-138798 is a backport of this pull request to the 3.14 branch.

bedevere-app · 2025-09-11T15:11:58Z

GH-138799 is a backport of this pull request to the 3.13 branch.

…miter=' '` require quotation for empty fields (GH-138006) (#138798) Co-authored-by: Maurycy Pawłowski-Wieroński <[email protected]>

…miter=' '` require quotation for empty fields (GH-138006) (#138799) Co-authored-by: Maurycy Pawłowski-Wieroński <[email protected]>

maurycy added 2 commits August 20, 2025 20:44

typo

0df5388

describe the behavior

6e4b9a5

bedevere-app bot added awaiting review docs Documentation in the Doc dir skip news labels Aug 20, 2025

github-project-automation bot added this to Docs PRs Aug 20, 2025

github-project-automation bot moved this to Todo in Docs PRs Aug 20, 2025

bedevere-app bot mentioned this pull request Aug 20, 2025

Document that CSV skipinitialspace=True and delimiter=' ' require quotation for empty fields #138005

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serhiy-storchaka reviewed Aug 21, 2025

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maurycy added 2 commits August 21, 2025 12:52

just one sentence

3bf1d88

bring back trailing space

eb5ea6a

maurycy requested a review from serhiy-storchaka August 21, 2025 10:53

serhiy-storchaka approved these changes Aug 22, 2025

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bedevere-app bot added awaiting merge and removed awaiting review labels Aug 22, 2025

serhiy-storchaka added needs backport to 3.13 bugs and security fixes needs backport to 3.14 bugs and security fixes labels Aug 22, 2025

sharktide approved these changes Aug 23, 2025

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hugovk merged commit e0f54a6 into python:main Sep 11, 2025
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bedevere-app bot removed the needs backport to 3.14 bugs and security fixes label Sep 11, 2025

bedevere-app bot removed the needs backport to 3.13 bugs and security fixes label Sep 11, 2025

hugovk pushed a commit that referenced this pull request Sep 11, 2025

[3.14] gh-138005: Document that CSV skipinitialspace=True and `deli…

5210e30

…miter=' '` require quotation for empty fields (GH-138006) (#138798) Co-authored-by: Maurycy Pawłowski-Wieroński <[email protected]>

hugovk pushed a commit that referenced this pull request Sep 11, 2025

[3.13] gh-138005: Document that CSV skipinitialspace=True and `deli…

a5f7e02

…miter=' '` require quotation for empty fields (GH-138006) (#138799) Co-authored-by: Maurycy Pawłowski-Wieroński <[email protected]>

maurycy deleted the csv-rst-typo branch September 13, 2025 08:39

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gh-138005: Document that CSV `skipinitialspace=True` and `delimiter=' '` require quotation for empty fields #138006

gh-138005: Document that CSV `skipinitialspace=True` and `delimiter=' '` require quotation for empty fields #138006

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	if (!field_len && dialect->delimiter == ' ' && dialect->skipinitialspace) {
	if (dialect->quoting == QUOTE_NONE \|\|
	(field == NULL &&
	(dialect->quoting == QUOTE_STRINGS \|\|
	dialect->quoting == QUOTE_NOTNULL)))
	{
	PyErr_Format(self->error_obj,
	"empty field must be quoted if delimiter is a space "
	"and skipinitialspace is true");
	return 0;
	}
	quoted = 1;
	}
	rec_len = join_append_data(self, field_kind, field_data, field_len,
	&quoted, 0);

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gh-138005: Document that CSV skipinitialspace=True and delimiter=' ' require quotation for empty fields #138006

gh-138005: Document that CSV skipinitialspace=True and delimiter=' ' require quotation for empty fields #138006

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gh-138005: Document that CSV `skipinitialspace=True` and `delimiter=' '` require quotation for empty fields #138006

gh-138005: Document that CSV `skipinitialspace=True` and `delimiter=' '` require quotation for empty fields #138006

maurycy commented Aug 20, 2025 •

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