7

I'm trying to write to a file but it's not working. I've gone through step-by-step with the debugger (it goes to the write command but when I open the file it's empty).

My question is either: "How do I see what the error is so I can debug?", "What can go wrong when trying to write to a file that would cause it to behave this way?".

sqlScript = open('script-file.sql', 'a')

    try:
         sqlScript.write(sqlLine)
    except IOError as (errno, strerror):
         print "I/O error({0}): {1}".format(errno, strerror)

This should be simple but I can't seem to find an answer. Also, I apologize in advance as English is a second language.

Edit: I put a print statement just before and the string is not empty.
Edit2: I'm using python 2.6 if that factors in somehow.

Edit 3: I've found a "solution" to my error. I decided to try and run my script using IDLE instead of PyCharm and it works like a charm (pun intended). I have no clue why, but there it is. Any reason why that would happen?!

Boona
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    What do you mean by "it's not working"? Does it generate the exception you're catching? Or is no exception generated? – alan Apr 04 '12 at 19:32
  • Did you close or flush the file in the Python process prior to inspecting it? – Fred Foo Apr 04 '12 at 19:32
  • Alan: It doesn't generate an error. Larsmans: I only open it to append. – Boona Apr 04 '12 at 19:44
  • Is this your actual code? Given the wrong indentation, I suspect not and that something else is affecting it. Have you tried running your code exactly as it is posted here (set sqlLine a value yourself)? It could be the problem lies elsewhere. You should also look into [the ``with`` statement](http://docs.python.org/py3k/reference/compound_stmts.html#the-with-statement) for writing files (``with open('script-file.sql', 'a') as sqlScript:``). – Gareth Latty Apr 04 '12 at 20:18
  • It's the actual code (only I changed the file name since it's a client's name.) It didn't keep my indentation when I copied it over so I put spaces myself. – Boona Apr 04 '12 at 20:29

7 Answers7

4

Building on Chris Morris' answer, maybe do something like this:

try:
    sqlScript.write(sqlLine)
except Exception as e:
    print type(e)
    print str(e)

This will catch any Exception thrown (provided it's a subclass of Exception, of course) and tell you the type and the error message.

Also, it's possible to define multiple except: cases for different possible exceptions, so maybe try doing that for each exception that might be potentially thrown/raised.

brettkelly
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2

The following code allows you to see what exception it is that is being thrown, and see a trace of where it originated from.

try:
    sqlScript.write(sqlLine)
except:
    print "Unexpected error:", sys.exc_info()[0]
    raise

See http://docs.python.org/tutorial/errors.html for more info.

Chris Morris
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1

You have to put your cursor at the beginning of the file. You can do that with seek method:

myScript.seek(0)

See this answer: https://stackoverflow.com/a/2949648/2119117

Community
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Lebugg
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0

If no exception is being tossed, I'd suspect the string variable 'sqlLine' is empty.

Did you print it before the write statement?

user590028
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0

Are the keywords in the script in lowercase? The same thing happened to me in another db and I solved it by changing words to UPPERCASE.

f p
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  • I don't even get a chance to run the script since I can't write it to the file. :P (Note: I'm not writing directly to the DB but generating a script that will be run at a later date.) – Boona Apr 04 '12 at 20:01
  • I just found the issue. When I tried running it with IDLE instead of PyCharm it worked. I have no idea why. :P – Boona Apr 04 '12 at 20:49
0

Your current working directory isn't what you expect it to be and it's successfully writing to some script-file.sql in another directory. Try printing os.getcwd() and make sure it's what you expect, and look in that directory.

kindall
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0

It happened on my linux environment but work on windows try

sqlScript = open('script-file.sql', 'a', buffering=False)

or

sqlScript = open('script-file.sql', 'a', 0)
nerdlyist
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JohnnyC
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