Made this compatible with Rails 3 and added some nice auto selection of fields.

lib/map_fields.rb

@@ -1,4 +1,4 @@
-require 'fastercsv'
+require 'csv'
 
 module MapFields
   VERSION = '1.0.0'
@@ -13,11 +13,11 @@ def map_fields
       :params => []
     }
     options = default_options.merge(
-                self.class.read_inheritable_attribute(:map_fields_options)
+                self.map_fields_options
               )
 
-    RAILS_DEFAULT_LOGGER.debug("session[:map_fields]: #{session[:map_fields]}")
-    RAILS_DEFAULT_LOGGER.debug("params[options[:file_field]]: #{params[options[:file_field]]}")
+    ::Rails.logger.debug("session[:map_fields]: #{session[:map_fields]}")
+    ::Rails.logger.debug("params[options[:file_field]]: #{params[options[:file_field]]}")
     if session[:map_fields].nil? || !params[options[:file_field]].blank?
       session[:map_fields] = {}
       if params[options[:file_field]].blank?
@@ -38,7 +38,7 @@ def map_fields
         session[:map_fields] = nil
         @map_fields_error =  InconsistentStateError
       else
-        expected_fields = self.class.read_inheritable_attribute(:map_fields_fields)
+        expected_fields = self.map_fields_fields
         if expected_fields.respond_to?(:call)
           expected_fields = expected_fields.call(params)
         end
@@ -52,18 +52,18 @@ def map_fields
     unless @map_fields_error
       @rows = []
       begin
-        FasterCSV.foreach(session[:map_fields][:file]) do |row|
+        CSV.foreach(session[:map_fields][:file]) do |row|
           @rows << row
           break if @rows.size == 10
         end
-      rescue FasterCSV::MalformedCSVError => e
+      rescue CSV::MalformedCSVError => e
         @map_fields_error = e
       end
-      expected_fields = self.class.read_inheritable_attribute(:map_fields_fields)
+      expected_fields = self.map_fields_fields
       if expected_fields.respond_to?(:call)
         expected_fields = expected_fields.call(params)
       end
-      @fields = ([nil] + expected_fields).inject([]){ |o, e| o << [e, o.size]}
+      @fields = ([nil] + expected_fields).inject({}){ |o, e| o.merge({e => o.size})}
       @parameters = []
       options[:params].each do |param|
         @parameters += ParamsParser.parse(params, param)
@@ -97,8 +97,10 @@ def map_fields_cleanup
 
   module ClassMethods
     def map_fields(actions, fields, options = {})
-      write_inheritable_attribute(:map_fields_fields, fields)
-      write_inheritable_attribute(:map_fields_options, options)
+      class_attribute :map_fields_fields, :instance_writer => false
+      class_attribute :map_fields_options, :instance_writer => false
+      self.map_fields_fields = fields
+      self.map_fields_options = options
       before_filter :map_fields, :only => actions
       after_filter :map_fields_cleanup, :only => actions
     end
@@ -135,7 +137,7 @@ def is_mapped?(field)
 
     def each
       row_number = 1
-      FasterCSV.foreach(@file) do |csv_row|
+      CSV.foreach(@file) do |csv_row|
         unless row_number == 1 && @ignore_first_row
           row = {}
           @mapping.each do |k,v|
@@ -195,7 +197,5 @@ def self.check_values(value, &block)
 
 if defined?(Rails) and defined?(ActionController)
   ActionController::Base.send(:include, MapFields)
-  ActionController::Base.view_paths.push File.expand_path(File.join(File.dirname(__FILE__), '..', 'views'))
-  #This is a hack but the above code is not enough when using bundler and Rails 2.3.5
-  ActionController::Base.view_paths.push "app/views"
+  ActionController::Base.prepend_view_path File.expand_path(File.join(File.dirname(__FILE__), '..', 'views'))
 end

map_fields.gemspec

@@ -5,7 +5,7 @@
 
 Gem::Specification.new do |s|
   s.name = %q{map_fields}
-  s.version = "1.0.4"
+  s.version = "1.0.5"
 
   s.required_rubygems_version = Gem::Requirement.new(">= 0") if s.respond_to? :required_rubygems_version=
   s.authors = ["Andrew Timberlake"]
@@ -27,7 +27,7 @@ Gem::Specification.new do |s|
     "spec/lib/params_parser_spec.rb",
     "spec/spec_helper.rb",
     "spec/test-file.csv",
-    "views/map_fields/_map_fields.erb"
+    "views/map_fields/_map_fields.html.erb"
   ]
   s.homepage = %q{http://github.com/internuity/map-fields}
   s.require_paths = ["lib"]

views/map_fields/_map_fields.erb → views/map_fields/_map_fields.html.erb

@@ -1,4 +1,4 @@
-<% form_tag nil, :id => 'map_fields_form', :method => :post do -%>
+<%= form_tag nil, :id => 'map_fields_form', :method => :post do %>
   <% @parameters.each do |arr| -%>
     <%= hidden_field_tag arr[0], arr[1] %>
   <% end -%>
@@ -7,7 +7,7 @@
       <thead>
         <tr>
           <% (1..@rows[0].size).each do |c| -%>
-            <th><%= select_tag "fields[#{c}]", options_for_select(@fields), :include_blank => true, :class => 'field_options' %></th>
+            <th><%= select_tag "fields[#{c}]", options_for_select(@fields, @fields[@rows[0][c-1].try(:capitalize)]), :include_blank => false, :class => 'field_options' %></th>
           <% end -%>
         </tr>
       </thead>