Python3 parsing json returns KeyError:

Question

I'm trying to parse a json file to extract key values to be used for objectives later. I can print some keys fine, but others don't return every key value in the json. Instead it returns a few then throws an error.

code example:

import json
import wget

#grab = wget.download('https://example.org/p/thread/3714047.json')

with open('3714047.json') as file:
    data = json.load(file)
    for i in data['posts']:
        print(i['now'])
        print(i['tim'])

json file example:

{
   "posts":[
      {
         "no":3714047,
         "now":"08\/24\/20(Mon)00:45:48",
         "name":"",
         "sub":"Cameras",
         "com":"so this is text.",
         "filename":"fujifilm_16589199_x_t3_mirrorless_digital_camera_1536757624_1433842",
         "ext":".jpg",
         "w":500,
         "h":500,
         "tn_w":250,
         "tn_h":250,
         "tim":1598244348346,
         "time":1598244348,
         "md5":"rqVskH5ul+hexgq5Vl3x8Q==",
         "fsize":47138,
         "resto":0,
         "bumplimit":1,
         "imagelimit":0,
         "semantic_url":"camera-recommendations",
         "replies":326,
         "images":21,
         "unique_ips":68
      },
  {
         "no":3714058,
         "now":"08\/24\/20(Mon)01:32:51",
         "name":"",
         "com":"some different text.",
         "time":1598247171,
         "resto":3714047
        },

the json file when hand counting has over 20+ 'tim': values. Not all entries has the tim key. here is my print output:

──(c4㉿ib)-[~/Desktop/test]
└─$ python3 a.py                                                                                         08/24/20(Mon)00:45:48
1598244348346
08/24/20(Mon)00:50:56
1598244656454
08/24/20(Mon)00:56:48
Traceback (most recent call last):
  File "a.py", line 11, in <module>
    print(i['tim'])
KeyError: 'tim'
                                                                                                             
┌──(c4㉿ib)-[~/Desktop/test]
└─$

Can anyone see what I am doing wrong? I've tried various ways with this being the closest I've gotten to get the values from the json I want.

When I use only 'now' everything works fine or 'now' with 'name' and so on. guessing it has something to do with tim being a number?

print(i['now'], i['name']):

  ┌──(c4㉿ib)-[~/Desktop/test]
└─$ python3 a.py                                                                                         1 ⨯
08/24/20(Mon)00:45:48 Anonymous
08/24/20(Mon)00:50:56 Anonymous
08/24/20(Mon)00:56:48 Anonymous
08/24/20(Mon)01:01:57 Anonymous
08/24/20(Mon)01:22:36 Anonymous
08/24/20(Mon)01:32:51 Anonymous
08/24/20(Mon)01:34:21 Anonymous
08/24/20(Mon)01:35:26 Anonymous
  ┌──(c4㉿ib)-[~/Desktop/test]
└─$

paul41 · Accepted Answer · 2020-09-02 19:58:58Z

1

If you use get it will not thrown an error if the key is not found and instead return None.

import json
import wget

#grab = wget.download('https://example.org/p/thread/3714047.json')

with open('3714047.json') as file:
    data = json.load(file)
    for i in data['posts']:
        print(i['now'])
        print(i.get('tim'))

This will print None for the ones missing tim, or you could check first to see if tim is None and only print it if there is a value.

answered Sep 2, 2020 at 19:58

paul41

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slurm · Accepted Answer · 2020-09-02 19:56:05Z

0

I figured out my problem. Still learning here.

What happen was in the json file not all lists contained the key 'tim' therefore during my loop when it came to a list with no value 'tim' it would error. I had to check if 'tim' was there.

with open('3714047.json') as file:
    data = json.load(file)
    test = []
    for i in data['posts']:
        test = i.get('tim')
        if test == None:
            pass
        else:
            #print(i['now'], i['name'])
            print(test)

answered Sep 2, 2020 at 19:56

slurm

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1 Comment

rici Over a year ago

You can do that test more simply: if 'tim' in i: print(i['tim']). (Or you could use `try ... catch KeyError: pass`` to skip processing if you get a KeyError.)

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