FlexibleCsv¶ ↑

Created by Chris Powers

The FlexibleCsv gem uses the FasterCSV gem to parse user created CSV files that may not have standard headers. For example, you know there’s an email address column somewhere in there, but it may be called “Email” or “Email Address” or “email-address”, and it might be in the first column, but it might be in the third.

Install¶ ↑

This gem is hosted by gemcutter.org, so just:

gem install flexible_csv

Examples¶ ↑

These CSV data snippets have the same data but are formatted much differently. Using FlexibleCsv to map possible column names to data nodes, these differences become negligible.

require 'flexible_csv'

# Arbitrary CSV data
csv_data1 = %Q{Full Name, Email Address\nJohn Doe, john@doe.com}
csv_data2 = %Q{Email, Name\njohn@doe.com, John Doe}

parser = FlexibleCsv.new do |csv|
  csv.column :full_name, "Name", "Full Name", "Client Name"
  csv.column :email, "Email", "Email Address"
end

parser.parse(csv_data1).each do |row|
  puts row.full_name #=> 'John Doe'
  puts row.email     #=> 'john@doe.com'
end

parser.parse(csv_data2).each do |row|
  puts row.full_name #=> 'John Doe'
  puts row.email     #=> 'john@doe.com'
end

Using Adapters¶ ↑

What if simply mapping header names to values is not enough? What if you need more translation logic? Instead of baking in complex rule functionality into FlexibleCsv, I am strongly suggesting users use their own adapter classes to wrap up this logic.

For example, let’s say that some of your CSV files have a column for each contact’s full name, but other have a separate column for first and last name:

require 'flexible_csv'

# Arbitrary CSV data
csv_data1 = %Q{Full Name\nJohn Doe}
csv_data2 = %Q{First Name, Last Name\nJohn,Doe}

parser = FlexibleCsv.new do |csv|
  csv.column :full_name, "Name", "Full Name", "Client Name"
  csv.column :first_name, "First Name", "First"
  csv.column :last_name, "Last Name", "Last", "Surname"
end

class CsvAdapter
  def initialize(row)
    @row = row
  end

  def full_name
    row.full_name || "#{row.first_name} #{row.last_name}"
  end

  def last_name
    row.last_name || row.full_name.split(' ').last
  end

  def first_name
    row.first_name || row.full_name.split(' ').first
  end

  def method_missing(method_name, *args)
    row.send(method_name, *args)
  end
end

parser.parse(csv_data1).each do |row|
  ad_row = CsvAdapter.new(row)
  puts ad_row.full_name  #=> 'John Doe'
  puts ad_row.first_name #=> 'John'
  puts ad_row.last_name  #=> 'Doe'
end

parser.parse(csv_data2).each do |row|
  ad_row = CsvAdapter.new(row)
  puts ad_row.full_name  #=> 'John Doe'
  puts ad_row.first_name #=> 'John'
  puts ad_row.last_name  #=> 'Doe'
end