CSV file of businesses.csv

CSV Mapper - Current.rb

# Given
class Business
  attr_accessor :name, :net_worth
  attr_accessor :line_1, :line_2, :city, :state, :zip
end

# Import with CSV Mapper
CsvMapper.import('path_to_file.csv') do
  map_to Business
  start_at_row 1      # Skip the first row (probably a header row)
  stop_at_row 10      # Stop parsing on the 10th row

  name                # Parse all attribute values to String
  net_worth                  
  line_1
  line_2
  city
  state.map {|row, index| row[index].to_s.upcase }   # Parse the raw value using the given block
  zip
end

# Results - An array of two instances of a Business

CSV Mapper - Proposed Verbose.rb

CsvMapper.import('path') do |business|
  map_to Business
  start_at_row 1      # Skip the first row (probably a header row)
  stop_at_row 10      # Stop parsing on the 10th row

  business.name
  business.net_worth :type => Float
  business.address.map Address do |address|
    address.line_1
    address.line_2
    address.city
    address.state.map {|value| value.to_s.upcase}
    address.zip
  end
end

CSV Mapper - Proposed.rb

# Given
class Business
  attr_accessor :name, :net_worth
  attr_accessor :address
  attr_accessor :employees
end

class Address
  attr_accessor :line_1, :line_2, :city, :state, :zip
end

class Employee
  attr_accessor :first_name, :last_name
end

# Import with CSV Mapper
CsvMapper.import('path') do |config|
  config.map_to Business
  config.start_at_row 1      # Skip the first row (probably a header row)
  config.stop_at_row 10      # Stop parsing on the 10th row

  name                       # Parse to String by default
  net_worth :type => Float   # Parse column value Float

  # Map an aggregate model that is an instance of Address
  address.map_to Address do 
    line_1
    line_2
    city
    state.map {|value| value.to_s.upcase}   # Parse the raw value using the given block
    zip
  end

  # Map a collection of employees that are instances of Employee
  employees.map_to Employee, :count => 2 do
    first_name
    last_name
  end
end

# Results - An array of two instances of a Business; each with a fully populated Address instance as the value of the address attribute

Maybe Better.rb

# Import with CSV Mapper
CsvMapper.import('path') do
  start_at_row 1      # Skip the first row (probably a header row)
  stop_at_row 10      # Stop parsing on the 10th row

  map_to Business do
    name                       # Parse to String by default
    net_worth :type => Float   # Parse column value Float
    net_worth.to_f             # Parse column value Float

    # Map an aggregate model that is an instance of Address
    address.map_to Address do 
      line_1(3)                  # Map explicitly by column index
      line_2("Address Line 2")   # Map explicitly by column header name (assumes zeroth row is header)
      city
      state.map {|value| value.to_s.upcase}   # Parse the raw value using the given block
      zip
    end

    # Map a collection of employees that are instances of Employee
    employees.map_to Employee, :count => 2 do
      first_name
      last_name
    end
  end
end