Writing a .CSV file in Python that works for both Python 2.7+ and Python 3.3+ in Windows

问题

EDIT: I put it in the title, but just realized I didn't mention it in the body. This seems to be specific to Windows.

I'm having a hard time writing output using the csv Python module in a script that works with both Python 2.7 and 3.3.

First try which works as expected in Python 2.7:

with open('test.csv', 'wb') as csv_file:
    writer = csv.DictWriter(csv_file, ['header1', 'header2'])
    writer.writeheader()
    for item in items:
        writer.writerow(item)

However, when that same thing is run in Python 3.3 you wind up with:

TypeError: 'str' does not support the buffer interface

So I change 'wb' to 'wt' and it runs, but now I have an extra blank row every other line in the file.

To fix that, I change:

with open('test.csv', 'wt') as csv_file:

to:

with open('test.csv', 'wt', newline='') as csv_file:

But now, it breaks Python 2.7:

TypeError: 'newline' is an invalid keyword argument for this function

I know I could just do something like:

try:
    with open('test.csv', 'wt', newline='') as csv_file:
        writer = csv.DictWriter(csv_file, ['header1', 'header2'])
        writer.writeheader()
        for item in items:
            writer.writerow(item)
except TypeError:
    with open('test.csv', 'wb') as csv_file:
        writer = csv.DictWriter(csv_file, ['header1', 'header2'])
        writer.writeheader()
        for item in items:
            writer.writerow(item)

However, that has some seriously bad duplication.

Does anyone have a cleaner way of doing this?

EDIT: The test data is simple and has no newlines or anything:

items = [{'header1': 'value', 'header2': 'value2'},
         {'header1': 'blah1', 'header2': 'blah2'}]

回答1:

I've tried a few ways. As far as I can see, simple using 'w' could be a solution:

with open('test.csv', 'w') as csv_file:
    writer = csv.DictWriter(csv_file, fieldnames=['header1', 'header2'], lineterminator='\n')
    # write something

回答2:

Here's a simpler generic way:

import sys

if sys.version_info[0] == 2:  # Not named on 2.6
    access = 'wb'
    kwargs = {}
else:
    access = 'wt'
    kwargs = {'newline':''}

with open('test.csv', access, **kwargs) as csv_file:
    writer = csv.DictWriter(csv_file, ['header1', 'header2'])
    writer.writeheader()
    for item in items:
        writer.writerow(item)

The principle here is not to try to fight the differences between Python 2 and 3 but to have conditional code. You can only go so far in writing code without this kind of test, sooner or later you will have to test the Python version.

来源：https://stackoverflow.com/questions/29840849/writing-a-csv-file-in-python-that-works-for-both-python-2-7-and-python-3-3-in