Assigning Variables from JSON in Python

Question

I've searched across dozens of answers for the last week but I haven't been able to find an example of what I'm trying to do, happy to be pointed to something that I've missed, and I'm new to Python so I apologise if this is something trivial.

I'm trying to read in a configuration from a JSON file so that I can abstract the configuration from the script itself.

I want to be able to assign the configuration value to a variable and perform an action on it, before moving on to the next category in a nested list, of which the categories could change/expand over time (music, pictures, etc).

The JSON file (library.json) currently looks like this:

{"media":{
    "tv": [{
        "source": "/tmp/tv",
        "dest": "/tmp/dest"
        }],
    "movies": [{
        "source": "/tmp/movies",
        "dest": "/tmp/dest"
    }]
}}

The relevant script looks like this:

import json
with open(libfile) as data_file:
data = json.load(data_file)

for k, v in (data['media']['tv']):
    print (k, v)

What I was hoping to see as output was:

dest /tmp/dest
source /tmp/tv

What I am seeing is:

dest source

It feels like I'm missing something simple.

Apologies in advance, my upvotes don't count because I am too much of a newbie. — Glen Kennedy
– Glen Kennedy, Commented Dec 3, 2018 at 2:00

Udhay · Accepted Answer · 2018-11-30 05:21:06Z

2

This works,

import json
with open('data.json') as json_file:
  data = json.load(json_file)
  for p in data['media']['tv']:
      dst = (p['dest'])
      src = (p['source'])
      print (src, dst)

answered Nov 30, 2018 at 5:21

Udhay

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2 Comments

Harshith Rai Over a year ago

Please add more explanation, telling how this would solve the problem and what approach you followed.

zhrist Over a year ago

@glen-kennedy I have detailed the answer and make it precise, so there are no confusions

Srce Cde · Accepted Answer · 2018-11-30 05:02:07Z

0

Something like this? Using f-strings and zip() that will aggregate elements.

import json
with open("dummy.json") as data_file:
    data = json.load(data_file)

for i, j in data["media"].items():
    print(i)
    print("\n".join(f'{str(k)} {str(l)}' for k,l in list(zip(j[0].keys(), j[0].values()))))
    print("\n")

Output:

tv
source /tmp/tv
dest /tmp/dest


movies
source /tmp/movies
dest /tmp/dest

answered Nov 30, 2018 at 5:02

Srce Cde

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2 Comments

Glen Kennedy Over a year ago

I assume I'm making a transcription mistake, but I am getting a syntax error on execution with this code:

with open(libfile) as data_file:     data = json.load(data_file) for i, j in data["media"].items():     print(i)     print("\n".join(f'{str(k)} {str(l)}' for k,l in list(zip(j[0].keys(), j[0].values()))))     print("\n")

Glen Kennedy Over a year ago

That would be it then, I am running 3.5.

Vasili Syrakis · Accepted Answer · 2018-11-30 05:14:05Z

0

The problem here is that data['media']['tv'] is actually a list of dictionaries.

You can tell because it looks like this: "movies": [{.. (Note the bracket [)

That means that instead of this:

for k, v in (data['media']['tv']):
    print (k, v)

You should be doing this:

for dct in (data['media']['tv']):
    for k, v in dct.items():
        print(k, v)

answered Nov 30, 2018 at 5:14

Vasili Syrakis

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1 Comment

Glen Kennedy Over a year ago

This also worked, which is confusing the crap out of me, because I am sure I tried this before and it threw up errors, but I think I had the items() in the wrong place previously. Thank you.

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