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apply

Applies a Python process(record) function, or a registered transform plugin, to each record. Either --script or --plugin is required.

Write with --output. A trailing path is not a positional argument.

# Script: the file must define process(record) -> dict
undatum apply --script transform.py data.jsonl --output output.jsonl

# Registered transform plugin
undatum apply data.jsonl --plugin example-transform --output out.jsonl

# Subset first, then transform
undatum apply --script transform.py --filter '`status` == "active"' data.jsonl --output out.jsonl

Install transform plugins via the undatum.plugins entry point; see Plugins.

Script contract​

The script is loaded with runpy.run_path. It must define process:

def process(record: dict) -> dict:
    record["name"] = str(record.get("name", "")).strip()
    return record

Missing process is a validation error. The function runs twice internally: a schema pass over at most 1000 records, then the write pass.

Options​

  • --script PATH — Python file with process
  • --plugin NAME — registered transform plugin instead of a script
  • --filter / --filter-expr — comparison expression before the transform (shared options)
  • --output — output path (stdout JSONL if omitted)
  • --format-in, --zipfile, --delimiter, --encoding, --start-page, --trust
  • --flatten-nested, --max-nested-depth, --keep-nested-parents / --no-keep-nested-parents, --on-error, --error-log, --table, --quotechar — shared options