pick particular string from a nested string using python

Question

How to pick error message from this error string:

[42000] [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Conversion failed when converting from a character string to uniqueidentifier. (8169) (SQLExecDirectW)

I just need to give the error:

Conversion failed when converting from a character string to uniqueidentifier.

to the user. How do i do it?

mohammed wazeem · Accepted Answer · 2020-03-24 06:52:02Z

4

You can use something like

s = "[42000] [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Conversion failed when converting from a character string to uniqueidentifier. (8169) (SQLExecDirectW)"
print(s[s.rfind(']')+1: s.find('(')])

answered Mar 24, 2020 at 6:52

mohammed wazeem

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1 Comment

Patrick Artner Over a year ago

works if the error is isolated. does not work if the error is contained more then once in a string (aka finding error inside a log file): bla [something]text1(bla)\nbla [some other thing]text2(bla)\n gives you an empty slice

Patrick Artner · Accepted Answer · 2020-03-24 09:37:14Z

2

If you want to find multiple occurences of this pattern in a longer text, @mohammedwazeems's solution no longer works.

In that case, use regex:

import re

regex = r".*](.+?)[(]"   # avoid all until last ] that is followed by captured anything lazyly
                         # that is followed by an open (

log_file = """some text that is fine
[42000] [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Conversion failed when converting from a character string to uniqueidentifier. (8169) (SQLExecDirectW)
more ok text
[42000] [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Fix me error. (8169) (SQLExecDirectW)
more okish text"""

matches = re.finditer(regex, log_file, re.MULTILINE)

for match in matches:

    if len(match.groups())>0:
        print ( match.group(1))

prints :

Conversion failed when converting from a character string to uniqueidentifier. 
Fix me error.

Test it here: https://regex101.com/r/GPWs2a/1

edited Mar 24, 2020 at 9:37

answered Mar 24, 2020 at 6:59

Patrick Artner

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2 Comments

Chadee Fouad Over a year ago

Perhaps it's easier to use something like this: error[error.rfind(']')+1:error.find('(')]

Patrick Artner Over a year ago

@ShadyMBA - if you look for that occurence in text that contains it exactly ONCE - yes. Try finding two to hundred occurences of that in one longer log file ... and you can't. Regex can. In fact stackoverflow.com/a/60826166/7505395 will get you NOTHING if you feed it text that contains the error message twice because the slice will look something like [99:43] (i.e. the first ] from back and first ( from back will target two different messages alltogether and get an empty slice.

Chadee Fouad · Accepted Answer · 2020-03-24 07:02:54Z

0

Try this:

error = '[42000] [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Conversion failed when converting from a character string to uniqueidentifier. (8169) (SQLExecDirectW)'
error[error.rfind(']')+1:error.find('(')]

That should give:

'Conversion failed when converting from a character string to uniqueidentifier. '

edited Mar 24, 2020 at 7:02

answered Mar 24, 2020 at 6:50

Chadee Fouad

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2 Comments

geek Over a year ago

Its not perticular message, it could me aything for example [42000] [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]PickMe. (8169) (SQLExecDirectW)

Chadee Fouad Over a year ago

he said " this error string" so he's very specific. If he needs it to be more generic then he needs to specify so in his question.

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