[FIXED] Get key name from Python KeyError exception

Issue

I would like to get the key name from the Python KeyError exception:

For example:

myDict = {'key1':'value1'}
try:
    x1 = myDict['key1']
    x2 = myDict['key2'] 
except KeyError as e:
    # here i want to use the name of the key that was missing which is 'key2' in this example
    print error_msg[missing_key]

i have already tried this

print e
print e.args
print e.message

my code is inside django view !

if i use ipython for example and try e.arg or e.message it works fine. but then i try it while inside a django view i get this results:

"Key 'key2' not found in <QueryDict: {u'key1': [u'value']}>" 
("Key 'key2' not found in <QueryDict: {u'key1': [u'value']}>",) 
Key 'key2' not found in <QueryDict: {u'key1': [u'value']}>

while i just want the 'key2'

Solution

As your dictionary is actually a QueryDict, and therefore returns a different error message, you will need to parse the exception message to return the first word in single quotes:

import re
#...
except KeyError as e:
    m = re.search("'([^']*)'", e.message)
    key = m.group(1)

Answered By - Jon Cairns