handling exception KeyError - Python

Question

I am getting a "KeyError" for a non-existing key in following code:

c.execute("SELECT * FROM table1 where col1 = 'test'")
res = c.fetchall()
sum = 0
for x in res:
    print "res: ",res

    d = {"num1"     : [  str(testVal[x[2]]['num1']) for x in res ],
         "num2"     : [ str(testVal[x[2]]['num2']) for x in res ],
         }
    conn.close()

This is the error:

    "num1": [  str(testVal[x[2]]['num1']) for x in res ],
KeyError: u'13'

How can I check to see if that key has value then assign it to "num1", "num2".

Could you edit your code? the quotes are pretty messy.. Also, it would be helpful to know on which line the error occurs. — unddoch, Jul 14 '15 at 21:43

score 0 · Accepted Answer · edited May 23 '17 at 11:43

0

Something like that:

"num1": [ str(ch_id[x[2]]['num1']) for x in res if x[2] in ch_id]

Since the execution is greedy, Python will not evaluate str(ch_id[x[2]]['num1']) if the condition is False, so you get no errors. It will just skip the missing keys. If you don't know this syntax, you can read here.

edited May 23 '17 at 11:43

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answered Jul 14 '15 at 21:50

unddoch

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handling exception KeyError - Python

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