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gh-67230: add quoting rules to csv module (GH-29469)

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Add two quoting styles for csv dialects.
They will help to work with certain databases in particular.

Automerge-Triggered-By: GH:merwok
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Skip Montanaro 2023-04-12 17:32:30 -05:00 committed by GitHub
parent 2b6e877767
commit 330a942b63
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 43 additions and 3 deletions
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22
Doc/library/csv.rst
View file

@ -327,7 +327,7 @@ The :mod:`csv` module defines the following constants:
Instructs :class:`writer` objects to quote all non-numeric fields.
Instructs the reader to convert all non-quoted fields to type *float*.
Instructs :class:`reader` objects to convert all non-quoted fields to type *float*.
.. data:: QUOTE_NONE
@ -337,7 +337,25 @@ The :mod:`csv` module defines the following constants:
character. If *escapechar* is not set, the writer will raise :exc:`Error` if
any characters that require escaping are encountered.
Instructs :class:`reader` to perform no special processing of quote characters.
Instructs :class:`reader` objects to perform no special processing of quote characters.
.. data:: QUOTE_NOTNULL
Instructs :class:`writer` objects to quote all fields which are not
``None``. This is similar to :data:`QUOTE_ALL`, except that if a
field value is ``None`` an empty (unquoted) string is written.
Instructs :class:`reader` objects to interpret an empty (unquoted) field as None and
to otherwise behave as :data:`QUOTE_ALL`.
.. data:: QUOTE_STRINGS
Instructs :class:`writer` objects to always place quotes around fields
which are strings. This is similar to :data:`QUOTE_NONNUMERIC`, except that if a
field value is ``None`` an empty (unquoted) string is written.
Instructs :class:`reader` objects to interpret an empty (unquoted) string as ``None`` and
to otherwise behave as :data:`QUOTE_NONNUMERIC`.
The :mod:`csv` module defines the following exception:

2
Lib/csv.py
View file

@ -9,12 +9,14 @@
unregister_dialect, get_dialect, list_dialects, \
field_size_limit, \
QUOTE_MINIMAL, QUOTE_ALL, QUOTE_NONNUMERIC, QUOTE_NONE, \
QUOTE_STRINGS, QUOTE_NOTNULL, \
__doc__
from _csv import Dialect as _Dialect
from io import StringIO
__all__ = ["QUOTE_MINIMAL", "QUOTE_ALL", "QUOTE_NONNUMERIC", "QUOTE_NONE",
"QUOTE_STRINGS", "QUOTE_NOTNULL",
"Error", "Dialect", "__doc__", "excel", "excel_tab",
"field_size_limit", "reader", "writer",
"register_dialect", "get_dialect", "list_dialects", "Sniffer",

4
Lib/test/test_csv.py
View file

@ -187,6 +187,10 @@ def test_write_quoting(self):
quoting = csv.QUOTE_ALL)
self._write_test(['a\nb',1], '"a\nb","1"',
quoting = csv.QUOTE_ALL)
self._write_test(['a','',None,1], '"a","",,1',
quoting = csv.QUOTE_STRINGS)
self._write_test(['a','',None,1], '"a","",,"1"',
quoting = csv.QUOTE_NOTNULL)
def test_write_escape(self):
self._write_test(['a',1,'p,q'], 'a,1,"p,q"',

2
Misc/NEWS.d/next/Library/2021-11-07-15-31-25.bpo-23041.564i32.rst Normal file
View file

@ -0,0 +1,2 @@
Add :data:`~csv.QUOTE_STRINGS` and :data:`~csv.QUOTE_NOTNULL` to the suite
of :mod:`csv` module quoting styles.

16
Modules/_csv.c
View file

@ -82,7 +82,8 @@ typedef enum {
} ParserState;
typedef enum {
QUOTE_MINIMAL, QUOTE_ALL, QUOTE_NONNUMERIC, QUOTE_NONE
QUOTE_MINIMAL, QUOTE_ALL, QUOTE_NONNUMERIC, QUOTE_NONE,
QUOTE_STRINGS, QUOTE_NOTNULL
} QuoteStyle;
typedef struct {
@ -95,6 +96,8 @@ static const StyleDesc quote_styles[] = {
{ QUOTE_ALL, "QUOTE_ALL" },
{ QUOTE_NONNUMERIC, "QUOTE_NONNUMERIC" },
{ QUOTE_NONE, "QUOTE_NONE" },
{ QUOTE_STRINGS, "QUOTE_STRINGS" },
{ QUOTE_NOTNULL, "QUOTE_NOTNULL" },
{ 0 }
};
@ -1264,6 +1267,12 @@ csv_writerow(WriterObj *self, PyObject *seq)
case QUOTE_ALL:
quoted = 1;
break;
case QUOTE_STRINGS:
quoted = PyUnicode_Check(field);
break;
case QUOTE_NOTNULL:
quoted = field != Py_None;
break;
default:
quoted = 0;
break;
@ -1659,6 +1668,11 @@ PyDoc_STRVAR(csv_module_doc,
" csv.QUOTE_NONNUMERIC means that quotes are always placed around\n"
" fields which do not parse as integers or floating point\n"
" numbers.\n"
" csv.QUOTE_STRINGS means that quotes are always placed around\n"
" fields which are strings. Note that the Python value None\n"
" is not a string.\n"
" csv.QUOTE_NOTNULL means that quotes are only placed around fields\n"
" that are not the Python value None.\n"
" csv.QUOTE_NONE means that quotes are never placed around fields.\n"
" * escapechar - specifies a one-character string used to escape\n"
" the delimiter when quoting is set to QUOTE_NONE.\n"