Python json.loads changes the order of the object

Question

I've got a file that contains a JSON object. It's been loaded the following way:

with open('data.json', 'r') as input_file:
  input_data = input_file.read()

At this point input_data contains just a string, and now I proceed to parse it into JSON:

data_content = json.loads(input_data.decode('utf-8'))

data_content has the JSON representation of the string which is what I need, but for some reason not clear to me after json.loads it is altering the order original order of the keys, so for instance, if my file contained something like:

{ "z_id": 312312,
  "fname": "test",
  "program": "none",
  "org": null
}

After json.loads the order is altered to let's say something like:

{ "fname": "test",
  "program": None,
  "z_id": 312312,
  "org": "none"
}

Why is this happening? Is there a way to preserve the order? I'm using Python 2.7.

If you really need order, then stackoverflow.com/questions/6921699/… — tdelaney
– tdelaney, Commented May 4, 2017 at 17:41
I believe this was a bad example because the keys are ordered alphabetically. I'll edit the example. My point is that I want the object not altered but to hold whatever order it had initially — Sebastian
– Sebastian, Commented May 4, 2017 at 17:43
If you need order, then use Python3.6: stackoverflow.com/q/39980323/7216865 — Maurice Meyer
– Maurice Meyer, Commented May 4, 2017 at 17:43

gen_Eric · Accepted Answer · 2017-05-04 17:41:10Z

36

Dictionaries (objects) in python have no guaranteed order. So when parsed into a dict, the order is lost.

If the order is important for some reason, you can have json.loads use an OrderedDict instead, which is like a dict, but the order of keys is saved.

from collections import OrderedDict

data_content = json.loads(input_data.decode('utf-8'), object_pairs_hook=OrderedDict)

answered May 4, 2017 at 17:41

gen_Eric

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1 Comment

user202729 Over a year ago

Since Python 3.7 json.loads preserves dict order by default.

Neil · Accepted Answer · 2017-05-04 17:39:08Z

3

This is not an issue with json.load. Dictionaries in Python are not order enforced, so you will get it out of order; generally speaking, it doesn't matter, because you access elements based on strings, like "id".

answered May 4, 2017 at 17:39

Neil

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1 Comment

Sebastian Over a year ago

It does matter in this case since I gotta dump the data into an excel file and need preserve the structure. All my files will not have the same structure so cannot access each element individually

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