ruby 18 lines · 6 steps

Parsing one CSV transaction row in Ruby

A single row string is validated, split, and coerced into a clean, typed transaction hash.

Explained by highlit
Intermediate parsing type-coercion error-handling data-cleaning
1require "csv"
2 
3def parse_transaction_row(line)
4 fields = CSV.parse_line(line, headers: false, skip_blanks: true)
5 return nil if fields.nil? || fields.empty?
6 
7 id, amount, description, tags = fields
8 
9 {
10 id: Integer(id),
11 amount: BigDecimal(amount),
12 description: description.to_s.strip,
13 tags: tags.to_s.split("|").map(&:strip).reject(&:empty?)
14 }
15rescue CSV::MalformedCSVError => e
16 Rails.logger.warn("Skipping malformed row: #{e.message}")
17 nil
18end
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Coercing raw strings into real types (Integer, BigDecimal) at the boundary keeps downstream code honest.
  2. 2BigDecimal, not Float, is the right choice for money to avoid rounding errors.
  3. 3A method-level rescue turns a parse failure into a skipped row instead of a crash.

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