Python reading JSON value, error

Question

I have simple JSON and after for I am reading values inside it.

this is a code:

 for row in returned_data['devices']:
     print (row['version'])

script print all "version" values and in the end

Traceback (most recent call last):
  File "api.py", line 370, in <module>
    main(sys.argv[1:])
  File "api.py", line 71, in main
    print (row['version'])
KeyError: 'version'

Why?

This indicates, that the key 'version' does not exist in a row. If you don't care if there are rows with missing version, you can prevent the error by using get function: row.get('version') — Igl3
– Igl3, Commented Jul 24, 2017 at 12:31
What's the input JSON? It looks like you have there a record inside returned_data['devices'] which doesn't have key version. — Qeek
– Qeek, Commented Jul 24, 2017 at 12:32
script print all "version" -s and in the end fails, I checked once all json-s arrays has "version" — Armen Arzumanyan
– Armen Arzumanyan, Commented Jul 24, 2017 at 12:43
Can you post the json please? Just censor sensitive data if you need to. — Igl3
– Igl3, Commented Jul 24, 2017 at 12:47

Igl3 · Accepted Answer · 2017-07-24 12:38:58Z

2

If you need every row to contain the key version, you have a mistake in your dictionary, because the exception is indicating, that there is a row, which is missing this key.

In this case you have to check why your dictionary is wrong.

Otherwise, if only some of the rows contain version and you don't need every row to have this key, you can get around the error by using .get() function like this:

for row in returned_data['devices']:
    print (row.get('version'))

This prints the version for every row, containing the key and None for the ones without version.

Another thing you could do is using a try...except...:

for row in returned_data['devices']:
    try:
        print (row['version'])
    except KeyError:
        print ("row does not contain 'version'")

answered Jul 24, 2017 at 12:38

Igl3

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1 Comment

Armen Arzumanyan Over a year ago

Thanks, I has error handling, but especially not check version is exist or not. Seems during json for/each some dirty data coming runtime.

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