CODEWITHSUNDEEP
pythonpython-2.7exceptionerror-handling
Ryflex
Ryflex

Reputation: 5769

Saving an error exceptions to file erroring out

I'm having some issues with a simple bit of code not working correctly and I'm totally baffled as to why...

errors = open('ERROR(S).txt', 'w')

try: 
    execfile("AEAPER.py")
except Exception as e:
    errors.write(e)

errors.close()

I get the following error:

Traceback (most recent call last):
  File "C:\Sator.py", line 45, in <module>
    periodically(2, -1, +1, callscripts)
  File "C:\Sator.py", line 27, in periodically
    s.run()
  File "C:\Python27\lib\sched.py", line 117, in run
    action(*argument)
  File "C:\Sator.py", line 36, in callscripts
    errors.write(e)
TypeError: expected a character buffer object

What is so wrong with my code and why is it doing that?

Upvotes: 0

Views: 56

Answers (3)

epochiero
epochiero

Reputation: 81

The write() method expects a string as an argument. You need to convert the exception object to a string:

try: 
    execfile("AEAPER.py")
except Exception as e:
    errors.write(str(e))

See here: http://docs.python.org/2/library/stdtypes.html#file.write

Upvotes: 1

abarnert
abarnert

Reputation: 365697

Unlike the print statement, the file.write function only takes strings. So, you just need to convert to string explicitly:

errors.write(str(e))

Of course in real-life code, you often want to do some formatting, so you often forget about this this. For example:

errors.write('Failed to exec {} with {}'.format(filename, e))

Here, we're passing the result of format to write, which is fine, and we're passing e as an argument to format, which is also fine… the fact that we've done an implicit conversion to string in the middle is easy to miss.

There are actually two different ways to represent a value as a string, str and repr, but str is the one that print uses, so it's probably what you wanted here.

Upvotes: 1

user2357112
user2357112

Reputation: 280335

e isn't a string. write needs a string. Make a string out of it with

repr(e)

or

str(e)

depending on what kind of output you want.

Upvotes: 1

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