When parsing CSV data that contains quoted strings with commas inside them, a simple String.split(",") won’t work:
# BAD: Breaks on quoted strings containing commas
"name,\"Smith, John\",age" |> String.split(",")
# => ["name", "\"Smith", " John\"", "age"] # Wrong!
Use a regex that respects quoted strings:
# GOOD: Handles quoted strings correctly
~r/,(?=(?:[^"]*"[^"]*")*[^"]*$)/
|> Regex.split("name,\"Smith, John\",age")
# => ["name", "\"Smith, John\"", "age"] # Correct!
The regex (?=(?:[^"]*"[^"]*")*[^"]*$) is a lookahead that only matches commas when there’s an even number of quotes after them (meaning we’re outside quotes).
For production code, consider using the NimbleCSV library instead, but this regex works well for quick parsing tasks.