Removing JSON property in array of objects

Question

I have a JSON array that I'm cleaning up in Python. I want to remove the imageData property:

data.json

[{"title": "foo", "imageData": "xyz123"},
{"title": "bar", "imageData": "abc123"},
{"title": "baz", "imageData": "def456"}]

I am setting up a list comprehension to remove the property, but I'm not sure how to create the variable that focuses on imageData:

import json

with open('data.json') as json_data:
    data = json.load(json_data)
    clean_data = [ item for item in data if not item['imageData'] ]
    # Write `clean_data` to new json file

When I print the list comprehension, it returns an empty array. What do I have to correct to get this working properly?

Stefano Sanfilippo · Accepted Answer · 2014-09-26 12:05:34Z

40

An easy solution to your problem is deleting the unwanted key in place, with del:

import json

with open('data.json') as json_data:
    data = json.load(json_data)
    for element in data: 
        del element['imageData']

You should add some safety checks, but you get the idea.

edited Sep 26, 2014 at 12:05

answered Oct 3, 2013 at 19:24

Stefano Sanfilippo

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Comments

Daniel Roseman · Accepted Answer · 2013-10-03 19:27:53Z

18

If not all the elements have an imageData key, then using del will cause an KeyError exception. You could guard against that by using pop with a default:

for item in data: 
    item.pop('image', None)

answered Oct 3, 2013 at 19:27

Daniel Roseman

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user1907906 · Accepted Answer · 2013-10-03 19:24:43Z

2

[ item for item in data if not item['imageData'] ]

is empty becaus all have imageData. You are just testing for it, not removing it.

Loop over date and del item['imageData'] on each item.

answered Oct 3, 2013 at 19:24

user1907906

Comments

wwii · Accepted Answer · 2013-10-03 20:28:27Z

1

How about:
clean_data = [k:v for k,v in data.iteritems() if k != 'imageData']

Or a dictionary expresion/comprehension if you want a dictionary:
clean_data = {k:v for k,v in data.iteritems() if k != 'imageData'}

answered Oct 3, 2013 at 20:28

wwii

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