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JSON Lines files (.jsonl, .ndjson) are read as CSV and profiled as broken fragments

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
45/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
javascript, python
Domain
cli, data

Research direction

Start by running the repro command, which reports 19 rows and 2 columns for a 20-line .jsonl file. The suffix routing is in read_table() in faircode/loaders.py and faircode/loaders_extra.py, and the web side is parseJSON() in assets/profiler-engine.js, with the accept list in profiler.html. Done means either .jsonl/.ndjson load as 20 records with a test in tests/test_loaders.py, or the suffix is rejected with a clear message. Maintainers have not chosen between the two options yet, so confirm which one before writing code.

Written by the indexing model from the issue text.

Description

bug enhancement help wanted

Where: faircode/loaders.py / faircode/loaders_extra.py read_table() (unknown suffix falls through to the CSV sniffer), assets/profiler-engine.js parseJSON(), assets/profiler-heldout.js / profiler.html (accept list), tests/test_loaders.py.

Current gap: a JSON Lines export (one object per line, the default of many tools) is neither supported nor rejected. The CLI reads it as comma-separated text, so each line is split inside the JSON braces and the "dataset" becomes columns named like {"sex": "f"; the report prints rows and columns and exits 0. The web engine reports "not valid JSON". Neither says that JSON Lines is the problem.

Repro:

$ python3 -c "import json; open('rows.jsonl','w').write('\n'.join(json.dumps({'sex': 'm' if i % 2 else 'f', 'age': 25 + i % 30}) for i in range(20)) + '\n')"
$ python3 -m faircode profile rows.jsonl | grep -E "Rows|Columns"
  Rows: 19    Columns: 2          # 20 records, two real columns, no error

Suggested approach: read .jsonl/.ndjson with pd.read_json(lines=True) (and in the web engine by parsing line by line), sharing the flatten rule, and add them to the file picker and the parity tests; if support is declined, reject the suffix with "JSON Lines is not supported: convert to a JSON array".

Dominant language
HTML
Stars
47
Forks
45
Avg merge
2h 55m
Merged PRs (30d)
54

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