python3 file open write exception handling

Question

Does the code below provide correct exception handling. My goal is, to not attempt the file.write() unless the file was successfully opened and ensure the file is closed. I am not concerned with the exact errors of why the file did not open or why the file did not write.

Python version 3.6.9. OS Linux.

data = "Some data"
filename = "test.txt"

try:
    file = open(filename, 'w+')
except:
    print("Error opening file")
else:
    try:
        file.write(data)
    except:
        print("Error writing to file")
finally:
    file.close()

Look at [What is a good way to handle exceptions when trying to read a file in python?](https://stackoverflow.com/questions/5627425/what-is-a-good-way-to-handle-exceptions-when-trying-to-read-a-file-in-python) — Nilesh Bhave, Apr 12 '22 at 04:22
A context handler (`with open`) would simplify this. You should basically never use a blanket `except`; always spell out which exception(s) exactly you want to handle. — tripleee, Apr 12 '22 at 04:50
I have updated my question to make the requirements of the code clearer. — user264427, Apr 12 '22 at 04:52
@tripleee I removed the code from the comments. Given the requirements of the code can you supply the correct code using with open ? — user264427, Apr 12 '22 at 05:50

score 1 · Accepted Answer · answered Apr 12 '22 at 05:56

You should basically never use a blanket except; always spell out which exception(s) exactly you want to handle.

Here is a refactoring using a context handler, so you can avoid the explicit finally: close

data = "Some data"
filename = "test.txt"

try:
    with open(filename, 'w+') as file:
        try:
            file.write(data)
        except (IOError, OSError):
            print("Error writing to file")
except (FileNotFoundError, PermissionError, OSError):
    print("Error opening file")

There may be more exceptions you should enumerate; I rattled these off off the top of my head.

python3 file open write exception handling

1 Answers1