[New-bugs-announce] [issue44512] csv.DictWriter: inconsistency in handling of extrasaction arg
Andrei Kulakov
report at bugs.python.org
Fri Jun 25 22:32:57 EDT 2021
New submission from Andrei Kulakov <andrei.avk at gmail.com>:
In csv.DictWriter, the arg `extrasaction` case is handled inconsistently:
- if it's misspelled, e.g. ignor instead of 'ignore', a ValueError is raised by the __init__ method.
- if it's 'Ignore', 'IGNORE', it will work properly
- if it's 'raise', it will also work properly
- BUT: if it's 'Raise' or 'RAISE', it will have the same effect as 'ignore'
The code is here: https://github.com/python/cpython/blob/main/Lib/csv.py#L135-L146
[ins] In [1]: from csv import DictWriter
[ins] In [4]: d=DictWriter(open('testcsv','w'),'abc',extrasaction='IGNORE')
[ins] In [5]: list(d._dict_to_list(dict(d=1)))
Out[6]: ['', '', '']
[ins] In [7]: d=DictWriter(open('testcsv','w'),'abc',extrasaction='RAISE')
[ins] In [8]: list( d._dict_to_list(dict(d=1)) )
Out[8]: ['', '', '']
[ins] In [9]: d=DictWriter(open('testcsv','w'),'abc',extrasaction='TEST')
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-9-953d1100c7f9> in <module>
----> 1 d=DictWriter(open('testcsv','w'),'abc',extrasaction='TEST')
/usr/local/Cellar/python at 3.9/3.9.1/Frameworks/Python.framework/Versions/3.9/lib/python3.9/csv.py in __init__(self, f, fieldnames, restval, extrasaction, dialect, *args, **kwds)
134 self.restval = restval # for writing short dicts
135 if extrasaction.lower() not in ("raise", "ignore"):
--> 136 raise ValueError("extrasaction (%s) must be 'raise' or 'ignore'"
137 % extrasaction)
138 self.extrasaction = extrasaction
ValueError: extrasaction (TEST) must be 'raise' or 'ignore'
[ins] In [10]: d=DictWriter(open('testcsv','w'),'abc',extrasaction='raise')
[ins] In [11]: list( d._dict_to_list(dict(d=1)) )
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-11-1fde207e1805> in <module>
----> 1 list( d._dict_to_list(dict(d=1)) )
/usr/local/Cellar/python at 3.9/3.9.1/Frameworks/Python.framework/Versions/3.9/lib/python3.9/csv.py in _dict_to_list(self, rowdict)
147 wrong_fields = rowdict.keys() - self.fieldnames
148 if wrong_fields:
--> 149 raise ValueError("dict contains fields not in fieldnames: "
150 + ", ".join([repr(x) for x in wrong_fields]))
151 return (rowdict.get(key, self.restval) for key in self.fieldnames)
ValueError: dict contains fields not in fieldnames: 'd'
----
I propose to accept any case of Raise, RAISE, etc, to have the effect of 'raise'.
I can put up the PR if that sounds good.
----------
components: Library (Lib)
messages: 396536
nosy: andrei.avk
priority: normal
severity: normal
status: open
title: csv.DictWriter: inconsistency in handling of extrasaction arg
versions: Python 3.10, Python 3.11, Python 3.9
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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue44512>
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