python print error

Question

sample.json

{
"datalist": [{
        "element1": "content",
        "element2": "content",
        "element3": "content"
    }, {
        "element1": "content",
        "element2": "content",
        "element3": "content"
    }, {
        "element1": "content",
        "element2": "content",
        "element3": "content"
    }

  ]
}

Python Code

import json

file = "/home/sample.json"

with open(file) as f:
  data = json.load(f)

for elem in data["datalist"]:
  print(elem["element1"] + ' \\ ' + elem["element2"] + ' \\ ' + elem["element3"])

Good Work Print Result : element1 \ element2 \ element3

But, another sample.json

{
"datalist": [{
        "element1": "content",
        "element2": "content",
        "element3": "content"
    }, {
        "element1": "content",
        "element3": "content"
    }, {
        "element1": "content",
        "element2": "content",
        "element3": "content"
    }

  ]
}

here in second section ; element2 does not exist

if element2 does not exist, it gives KeyError: 'element2'

for elem in data["datalist"]:
  print(elem["element1"] + ' \\ ' + elem["element2"] + ' \\ ' + elem["element3"])

printing first section but when it comes second section stop and KeyError: 'element2'

how can fix it ? thx.

You can use some if statement checking the length. If the length is 2, you can print element one and element 3. Else print all three elements — Sheldore
– Sheldore, Commented Aug 23, 2018 at 22:08
thx, how to? @Bazingaa i want result : 1.line element1 \ element2 \ element3 2.line element1 \ (space or blabla) \ element3 3.line element1 \ element2 \ element3 — tioma
– tioma, Commented Aug 23, 2018 at 22:10

Kevin He · Accepted Answer · 2018-08-23 22:10:53Z

2

Python dictionaries have a get method that allows you to return a default value if the key is not found. For example, if d = { 1: 2, 3: 4 }; v = 10, d.get(1, v) gives 2, d.get(5, v) gives 10.

So this case you can just give a default value to your code such as elem.get('element2', '[element2 missing]') to signify a missing element in the print outputs and the code will run error-free.

answered Aug 23, 2018 at 22:10

Kevin He

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Comments

danuker · Accepted Answer · 2018-08-23 21:30:58Z

0

There are multiple options:

Fix the program, to tolerate missing data
Fix the data, to be parse-able by the program

Fixing the program

Instead of:

print(elem["element1"] + ' \\ ' + elem["element2"] + ' \\ ' + elem["element3"])

you need to check whether the elements are there:

if "element1" in elem.keys() and "element2" in elem.keys() and  "element3" in 
elem.keys():
    print(elem["element1"] + ' \\ ' ...

Fixing the data

Of course, this is easiest: add a key and a value for "element2" in the second dictionary from datalist.

answered Aug 23, 2018 at 21:30

danuker

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2 Comments

tioma Over a year ago

I worked but it was incomplete and not what I wanted :( ignoring all element2 ? if there is no element2, i want to leave it space (" ") instead or write "blabla"

tioma Over a year ago

i want result : element1 \ element2 \ element3 element1 \ (space or blabla) \ element3 element1 \ element2 \ element3

SF12 Study · Accepted Answer · 2019-06-24 05:21:57Z

0

The Try & Except Statement Can Be Used:

import json

file = 'home/sample.json'

with open(file) as f:
    data = json.load(f)


try:
    for elem in data["datalist"]:
        print(elem["element1"] + ' \\ ' + elem["element2"] + ' \\ ' + elem["element3"])

except KeyError as e:
    print(e, "Does Not Exist")

And There Was Some Errors In Your Code

edited Jun 24, 2019 at 5:21

answered Jun 24, 2019 at 5:14

SF12 Study

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