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Python outputting json.dump like json.tool

21 Oct 2017

Sometimes, it is desirable in Python command line utilities to export JSON pretty printed similar to python -m json.tool. Typically, one could pretty print any arbitrary JSON using the Python module json.tool.

python -m json.tool < compact.json > pretty.json

If writing a CLI utility which exports JSON via json.dump, then it may be useful to offer users a --pretty-json option. To replicate json.dumps like json.tool the following can be printed to stdout.

import json

with open('path/to/compact.json') as f:
    json_object = json.load(f)

print json.dumps(json_object, indent=4, separators=(',', ': '), sort_keys=True)

To write to a file using json.dump like json.tool:

import json

with open('compact.json') as f:
    json_object = json.load(f)

with open('pretty.json', 'w') as f:
    json.dump(json_object, f, indent=4, separators=(',', ': '), sort_keys=True)
    #add trailing newline for POSIX compatibility

This article was last updated Nov 19, 2017.

Posted in Engineering with tags: Python, Tips