From: Paul Br <brr@...>
Date: 2006-11-02T10:30:03+09:00
Subject: Input file, change data, write to file

I'm a ruby newbie trying to read data from a file, make a few changes, 
and write the output to a file so it can be imported into a MySQL 
database.

I found a partial solution on page 138 in Maik Schmidt's “Enterprise 
Integration with Ruby” book but it lacks a means to write the output to 
a file.

How can I write the output to a file using the below code?

For what it's worth, I'll be working with files that contain between 
20,000 – 60,000 rows.

Below is a data sample:

01234567890123456789012345678901234567890123456789012

00123 random text   3.0010/20/200610/21/2006   -3.45
00253 more   text 275.0007/01/200606/12/2006   12.45

Here's what I want the file to look like with tabs between each section:

01234567890123456789012345678901234567890123456789012
123 random text    3.00 2006-10-20 2006-10-21  -3.45
253 more   text  275.00 2006-07-01 2006-06-12  12.45

Filename: fixtest1.rb

class FixedLengthRecordFile
  def FixedLengthRecordFile.open(filename, field_sizes)

    if field_sizes.nil? or field_sizes.empty?
      raise ArgumentError, "Empty field sizes not allowed!"
    end

    field_pattern = 'a' + field_sizes.join('a')
    IO.foreach(filename) do |line|
      record = line.chomp.unpack(field_pattern)
      record.map { |f| f.strip! }
      yield record
    end
  end
end

Filename: rw1.rb

require 'fixtest1'

FixedLengthRecordFile.open('test1.abc', [2, 3, 12, 7, 2, 1, 2, 1, 4, 2, 
1, 2, 1, 4, 10]) do |row|
  puts 
"#{row[1]}\t#{row[2]}\t#{row[3]}\t#{row[8]}-#{row[4]}-#{row[6]}\t#{row[13]}-#{row[9]}-#{row[11]}\t#{row[14]}"

Any feedback is greatly appreciated!

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