From: Andrew Timberlake <andrew@...>
Date: 2009-10-01T18:39:13+09:00
Subject: Re: FasterCSV - varying headers

On Thu, Oct 1, 2009 at 10:09 AM, Sean Mcknew <smcknew@gmail.com> wrote:
> Hello,
>
> Quick warning: I am very much a ruby newbie and am extremely new to
> programming in general.
>
> I'm attempting to build a little program that  operates on a large csv
> file (potentially 100,000+ lines), but the challenge is that while I
> will have a couple required columns, I must provide some naming
> flexibility as it is unlikely that the user will be able to match my
> headers word for word in every case. As such, my goal is to provide an
> interface that asks what each header should represent and then treat the
> user's headers as if they followed my original specifications exactly.
>
> For example, let's say that I require the following columns:  Product
> Title, Product Price.  If the user were to provide me with the headers
> worded as  Product Name and Product Pricing, I would want to assign
> 'Product Name' to represent 'Product Title.'
>
>  I suspect that throwing the headers into a hash would be ideal, but
> I'm not entirely sure how to approach it. Here an excerpt from my
> attempt thus far...
>
>
> require "rubygems"
> require "fastercsv"
>
> class HeaderProcessing
>  attr_accessor :file
>  attr_accessor :headers
>  attr_accessor :clientid
>  attr_accessor :product_title_header, :product_price_header
>
>
>  def initialize
>  puts "What is the client ID?"
>  @clientid = gets.chomp
>    open_file
>  end
>
>  def open_file
>    infile = "tobeprocessed/#{@clientid}.csv"
>    outfile = "tobeprocessed/#{@clientid}_out.csv"
>  csv =  FasterCSV.read(infile,  {:headers => true, :return_headers =>
> true, :header_converters => :symbol})
>     # Not sure if read is the best approach here, since some files
> could get quite large.
>    puts "The user's headers are "
>    puts csv.headers.inspect
>    puts "\n \n Please enter the user supplied Product Title header"
>  @product_title_header = gets.chomp
>     puts "\n \n Please enter the user supplied Product Price"
>  @product_price_header = gets.chomp
>  # I do this with each required and optional header. Not very DRY for
> now...
>  #  I now have each of the user's headers I intend to use in a number of
> instance variables.
>  # placeholder for user product data clean up
>  File.open(outfile, "w") { |f| f.puts csv }
>    end
>  end
> queued = HeaderProcessing.new
>
>
> If I understand FasterCSV correctly, by setting :headers to true, the
> csv file was read as a table object. Is  it possible to turn the table's
> headers into a hash and then set each key/value to the appropriate
> variable (as per @product_title_header etc)?   If so, how?  I've been
> rummaging through the FasterCSV docs that I believe pertain to the
> question, but I'm a bit lost on the actual implementation
>
> Is it also feasible to save these hash definitions to a separate file so
> that I won't have to go through the same process when/if the user
> provides a new file with updated prices? Alternatively, if there's a
> more appropriate way to tackle this, I'm all ears.
>
> Thanks in advance!
> Inf
> --
> Posted via http://www.ruby-forum.com/.
>
>

I wrote a rails plugin which does this type of translation between
user supplied columns and expected columns. It is specific to Rails
but you might be able to get some ideas from it.
http://github.com/internuity/map-fields

Andrew Timberlake
http://ramblingsonrails.com

http://MyMvelope.com - The SIMPLE way to manage your savings