Python3: JSON to CSV

Question

I have a JSON dict in Python which I would like to parse into a CSV, my data and code looks like this:

import csv
import json

x = {
"success": 1,
"return": {
    "variable_id": {
        "var1": "val1",
        "var2": "val2"
    }...

f = csv.writer(open("foo.csv", "w", newline=''))
for x in x:
    f.writerow([x["success"],
                '--variable value--',
                x["return"]["variable_id"]["var1"],
                x["return"]["variable_id"]["var2"])

However, since variable_id's value is going to change I don't know how to refer to in the code. Apologies if this is trivial but I guess I lack the terminology to find the solution.

x is not a JSON object, it's just a dict

C8H10N4O2
– C8H10N4O2

2017-08-10 13:05:07 +00:00
Commented Aug 10, 2017 at 13:05 — C8H10N4O2
– C8H10N4O2, Commented Aug 10, 2017 at 13:05

Unatiel · Accepted Answer · 2017-08-10 13:44:41Z

3

You can use the * (unpack) operator to do this, assuming only the values in your variable_id matter :

f.writerow([x["success"],
           '--variable value--',
           *[val for variable_id in x['return'].values() for val in variable_id.values()])

The unpack operator essentially takes everything in x["return"]["variable_id"].values() and appends it in the list you're creating as input for writerow.

EDIT this should now work if you don't know how to referencevariable_id. This will work best if you have several variable_ids in x['return'].

If you only have one variable_id, then you can also try this :

f.writerow([x["success"],
           '--variable value--',
           *list(x['return'].values())[0].values()])

Or

f.writerow([x["success"],
           '--variable value--',
           *next(iter(x['return'].values())).values()])

edited Aug 10, 2017 at 13:44

answered Aug 10, 2017 at 13:08

Unatiel

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4 Comments

Zach Cleary Over a year ago

Sorry, perhaps I was unclear but the issue is that I cannot use "variable_id", as it is not a constant, it will change for each x["return"], hence I don't know how to reference it. Perhaps there is a kind of placeholder/variable syntax I'm unaware of?

Unatiel Over a year ago

I've updated my answer so it would work if the key(s) in x['return'] is(are) not constant(s). Something better may exist, but it should work. Of course, you can (should) use a generator instead of a list comprehension.

Zach Cleary Over a year ago

Thank you, this now works, except for it writes everything to the same row, any idea how to make it write each variable_id on separate ones?

Unatiel Over a year ago

You could probably do this in a single line : f.writerows([[x['success'], '--variable value--', *vals] for vals in x['return'].values()]) or something like that.

Ray Wang · Accepted Answer · 2017-08-10 12:45:25Z

1

You can get variable_id's value using x['success']['return'].keys[0].

answered Aug 10, 2017 at 12:45

Ray Wang

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