How can I convert JSON to CSV?

Question

I have a JSON file that I want to covert to a CSV file. How can I do this with Python?

I tried:

import json
import csv

f = open('data.json')
data = json.load(f)
f.close()
f = open('data.csv')
csv_file = csv.writer(f)
for item in data:
    f.writerow(item)

f.close()

However, it did not work. I am using Django and the error I received is:

file' object has no attribute 'writerow'

So, then I tried the following:

import json
import csv

f = open('data.json')
data = json.load(f)
f.close()

f = open('data.csv')
csv_file = csv.writer(f)
for item in data:
    csv_file.writerow(item)

f.close()

I then get the error:

sequence expected

Sample json file:

[
  {
    "pk": 22,
    "model": "auth.permission",
    "fields": {
      "codename": "add_logentry",
      "name": "Can add log entry",
      "content_type": 8
    }
  },
  {
    "pk": 23,
    "model": "auth.permission",
    "fields": {
      "codename": "change_logentry",
      "name": "Can change log entry",
      "content_type": 8
    }
  },
  {
    "pk": 24,
    "model": "auth.permission",
    "fields": {
      "codename": "delete_logentry",
      "name": "Can delete log entry",
      "content_type": 8
    }
  },
  {
    "pk": 4,
    "model": "auth.permission",
    "fields": {
      "codename": "add_group",
      "name": "Can add group",
      "content_type": 2
    }
  },
  {
    "pk": 10,
    "model": "auth.permission",
    "fields": {
      "codename": "add_message",
      "name": "Can add message",
      "content_type": 4
    }
  }
]

Answer 1

I am not sure this question is solved already or not, but let me paste what I have done for reference.

First, your JSON has nested objects, so it normally cannot be directly converted to CSV. You need to change that to something like this:

{
    "pk": 22,
    "model": "auth.permission",
    "codename": "add_logentry",
    "content_type": 8,
    "name": "Can add log entry"
},
......]

Here is my code to generate CSV from that:

import csv
import json

x = """[
    {
        "pk": 22,
        "model": "auth.permission",
        "fields": {
            "codename": "add_logentry",
            "name": "Can add log entry",
            "content_type": 8
        }
    },
    {
        "pk": 23,
        "model": "auth.permission",
        "fields": {
            "codename": "change_logentry",
            "name": "Can change log entry",
            "content_type": 8
        }
    },
    {
        "pk": 24,
        "model": "auth.permission",
        "fields": {
            "codename": "delete_logentry",
            "name": "Can delete log entry",
            "content_type": 8
        }
    }
]"""

x = json.loads(x)

f = csv.writer(open("test.csv", "wb+"))

# Write CSV Header, If you dont need that, remove this line
f.writerow(["pk", "model", "codename", "name", "content_type"])

for x in x:
    f.writerow([x["pk"],
                x["model"],
                x["fields"]["codename"],
                x["fields"]["name"],
                x["fields"]["content_type"]])

You will get output as:

pk,model,codename,name,content_type
22,auth.permission,add_logentry,Can add log entry,8
23,auth.permission,change_logentry,Can change log entry,8
24,auth.permission,delete_logentry,Can delete log entry,8

Answer 2

A generic solution which translates any json list of flat objects to csv.

Pass the input.json file as first argument on command line.

import csv, json, sys

input = open(sys.argv[1])
data = json.load(input)
input.close()

output = csv.writer(sys.stdout)

output.writerow(data[0].keys())  # header row

for row in data:
    output.writerow(row.values())

Answer 3

With the pandas library, this is as easy as using two commands!

pandas.read_json()

To convert a JSON string to a pandas object (either a series or dataframe). Then, assuming the results were stored as df:

df.to_csv()

Which can either return a string or write directly to a csv-file.

Based on the verbosity of previous answers, we should all thank pandas for the shortcut.

Answer 4

It'll be easy to use csv.DictWriter(),the detailed implementation can be like this:

def read_json(filename):
    return json.loads(open(filename).read())
def write_csv(data,filename):
    with open(filename, 'w+') as outf:
        writer = csv.DictWriter(outf, data[0].keys())
        writer.writeheader()
        for row in data:
            writer.writerow(row)
# implement
write_csv(read_json('test.json'), 'output.csv')

Note that this assumes that all of your JSON objects have the same fields.

Here is the reference which may help you.

Answer 5

This code should work for you, assuming that your JSON data is in a file called data.json.

import json
import csv

with open("data.json") as file:
    data = json.load(file)

with open("data.csv", "w") as file:
    csv_file = csv.writer(file)
    for item in data:
        csv_file.writerow([item['pk'], item['model']] + item['fields'].values())

Answer 6

I was having trouble with Dan's proposed solution, but this worked for me:

import json
import csv 

f = open('test.json')
data = json.load(f)
f.close()

f=csv.writer(open('test.csv','wb+'))

for item in data:
  f.writerow([item['pk'], item['model']] + item['fields'].values())

Where "test.json" contained the following:

[ 
{"pk": 22, "model": "auth.permission", "fields": 
  {"codename": "add_logentry", "name": "Can add log entry", "content_type": 8 } }, 
{"pk": 23, "model": "auth.permission", "fields": 
  {"codename": "change_logentry", "name": "Can change log entry", "content_type": 8 } }, {"pk": 24, "model": "auth.permission", "fields": 
  {"codename": "delete_logentry", "name": "Can delete log entry", "content_type": 8 } }
]