Get specific field values from Json Python

Question

I have JSON in response and I'm trying to get all "Id" and "Pages" values and put them to an array (or list) for next steps

[
{
    "Page": 1,
    "Content": [
        {"Id": 100000000000001,"Title": "title1", ...},
        {"Id": 100000000000002,"Title": "title2", ...},
        {"Id": 100000000000003,"Title": "title3", ...}
    ]
},
{
    "Page": 2,
    "Content": [
        {"Id": 100000000000004,"Title": "title4", ...},
        {"Id": 100000000000005,"Title": "title5", ...},
        {"Id": 100000000000006,"Title": "title6", ...}
    ]
},
{
    "Page": 3,
    "Content": [
        {"Id": 100000000000007,"Title": "title7", ...},
        {"Id": 100000000000008,"Title": "title8", ...},
        {"Id": 100000000000009,"Title": "title9", ...}
    ]
}

]

Got "Page" values by using pages = [ e['Page'] for e in data ] from here

Can't get "Id" values. Tried

for el in data: print (el['Content']['Id'])

But got error TypeError: list indices must be integers or slices, not str

Can you help me?

Update1: Sorry for my slightly incorrectly asked question: as output from this JSON I want to return array ["id1","id2",...,"id9"], not print

sahasrara62 · Accepted Answer · 2020-04-16 03:22:16Z

1

using list comprehension you can do this easily

a = [
{
    "Page": 1,
    "Content": [
        {"Id": 100000000000001,"Title": "title1",  },
        {"Id": 100000000000002,"Title": "title2",  },
        {"Id": 100000000000003,"Title": "title3",  }
    ]
},
{
    "Page": 2,
    "Content": [
        {"Id": 100000000000004,"Title": "title4",  },
        {"Id": 100000000000005,"Title": "title5",  },
        {"Id": 100000000000006,"Title": "title6",  }
    ]
},
{
    "Page": 3,
    "Content": [
        {"Id": 100000000000007,"Title": "title7",  },
        {"Id": 100000000000008,"Title": "title8",  },
        {"Id": 100000000000009,"Title": "title9",  }
    ]
}

]

res = [[i['Page'],[ j['Id'] for j in i['Content']]] for i in a]
print(res)

output

[[1, [100000000000001, 100000000000002, 100000000000003]],
 [2, [100000000000004, 100000000000005, 100000000000006]],
 [3, [100000000000007, 100000000000008, 100000000000009]]]

answered Apr 16, 2020 at 3:22

sahasrara62

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1 Comment

Adam Over a year ago

Thanks for your answer. Sorry for my slightly incorrectly asked question: As output from my JSON I want to return array ["id1","id2",...,"id9"], but not print these "ID"s

marc_s · Accepted Answer · 2020-04-19 06:08:40Z

This is only an addition to the answers already given, just in case u come across more nested paths : jmespath makes it easy to traverse through nested lists and dicts :

The path to pages is data -> list -> page ... so u access the data, next a list, then the page key

Same applies to id : data ->list ->content -> list ->id

In jmespath, a key is accessed via a dot, while lists are accessed via brackets([]):

import jmespath
expression = jmespath.compile('[].{page:Page,id:Content[].Id}')
expression.search(data)

[{'page': 1, 'id': [100000000000001, 100000000000002, 100000000000003]},
 {'page': 2, 'id': [100000000000004, 100000000000005, 100000000000006]},
 {'page': 3, 'id': [100000000000007, 100000000000008, 100000000000009]}]

jmespath allows u to compile a search path, similar to the functionality in python's re module. it's more of a tool to keep handy when you come across really nested paths.

michaeldel · Accepted Answer · 2020-04-16 02:55:25Z

0

Your 'Content' field is a list, with potentially multiple elements themselves containing an 'Id' field. If you want to print them all, here is one way to do it

for element in data:
    ids = [c['id'] for c in element['Content']]
    print(ids)

answered Apr 16, 2020 at 2:55

michaeldel

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2 Comments

Adam Over a year ago

Thanks for your answer. Two more questions, if you don't mind: 1. How can I put "id" to array (don't want to print them right away)? Because now it prints array with arrays inside 2. How to convert array with arrays [[],[],[]] to one array with all values? As general output I want to get array ["id1", "id2", "id3",...,"id9"]

michaeldel Over a year ago

flattened = [element for subarray in array for element in subarray]

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