json.md

Working with JSON

Saving

import json
with open('data.json', 'w') as fp:
    json.dump(data, fp)

Supply extra arguments like sort_keys or indent to get a pretty result. The argument sort_keys will sort the keys alphabetically and indent will indent your data structure with indent=N spaces.

json.dump(data, fp, sort_keys=True, indent=4)

Loading

with open('data.json', 'r') as fp:
    data = json.load(fp)

json.dump() vs json.dumps(), json.load() vs json.loads()

If you want to dump the JSON into a file/socket or whatever, then you should go for dump(). If you only need it as a string (for printing, parsing or whatever) then use dumps() (dump string). The functions with an s take string parameters. The others take file streams.

Query JSON

JMESPath is a query language for JSON, which allows you to obtain the data you need from a JSON document or dictionary easily. This library is available for Python, but also for many other programming languages, meaning that if you master the JMESPath query language, you can use it in many places. Here's some example code to get a feeling for what's possible:

import jmespath

persons = {
   "persons": [
     { "name": "erik", "age": 38 },
     { "name": "john", "age": 45 },
     { "name": "rob", "age": 14 }
   ]
}
jmespath.search('persons[*].age', persons)
# [38, 45, 14]

References

• python.land/data-processing/working-with-json/jmespath