How to create a nested array of JSON objects using Python?

Question

Desired output:

{"MainKey": 
   [{"key01":"value01","key02":"value02"},
    {"key11":"value11","key22":"value02"}
   ]
}

The code I tried:

data = {}
data2=[{}]

data2[0]['key01'] = 'value01'
data2[0]['key02']=  'value02'

data2[1]['key11'] = 'value11'  #index out of bounds error
data2[1]['key12']=  'value12'

data['MainKey']=data2

import json 
with open('try.json", 'w') as outfile:
 json.dump(data,outfile)

But this gives index out of bounds error for the second set of values in data2. How do i solve this?

You are getting the error because you only have one dict in data2 try: data2=[{}, {}] — Rakesh
– Rakesh, Commented Jun 18, 2018 at 10:07
@Rakesh How would i make an array with n number of such items though? — Nand gopal
– Nand gopal, Commented Jun 18, 2018 at 10:10

Rakesh · Accepted Answer · 2018-06-18 10:13:39Z

2

One approach is to create the number of dict using range.

Ex:

data = {}

data2 = [{} for i in range(2)]

data2[0]['key01'] = 'value01'
data2[0]['key02']=  'value02'

data2[1]['key11'] = 'value11'
data2[1]['key12']=  'value12'

data['MainKey']=data2
print(data)

Output:

{'MainKey': [{'key01': 'value01', 'key02': 'value02'}, {'key12': 'value12', 'key11': 'value11'}]}

answered Jun 18, 2018 at 10:13

Rakesh

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1 Comment

Rakesh Over a year ago

Please accept ans if it solved your problem. Thanks.

Surya Tej · Accepted Answer · 2018-06-18 10:09:49Z

0

data2 is a list with only one item, so its index cannot be greater than 0.

>>> data2=[{}]
>>> data2[0]['key01'] = 'value01'
>>> data2[0]['key02'] = 'value02'
>>> data2

[{'key01': 'value01', 'key02': 'value02'}]

answered Jun 18, 2018 at 10:09

Surya Tej

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2 Comments

Nand gopal Over a year ago

I figured, but how do i solve this and make an array with n number of {} items in data2?

Surya Tej Over a year ago

data2 = [{} for i in range(n)]

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