Create rake task (import:bikes:csv, import:bikes:analyze_csv) & importing class

app/models/bikes_csv_importer.rb

@@ -0,0 +1,67 @@
+require 'csv'
+
+class BikesCsvImporter
+  attr_reader :file
+
+  def initialize(file)
+    @file = file
+  end
+
+  def run
+    fetch do |bike_hash|
+      import_bike bike_hash
+    end
+  end
+
+  def analyze(fields = [])
+    fields = fields.map &:downcase
+    grouped = {}
+    fetch do |bike_hash|
+      bike_hash.each do |key, value|
+        next if fields.any? && !fields.include?(key.downcase)
+        grouped[key]        ||= {}
+        grouped[key][value] ||= 0
+        grouped[key][value]  += 1
+      end
+    end
+    grouped
+  end
+
+
+
+  private
+
+  def fetch
+    CSV.foreach(file).each_with_index do |row, i|
+      if i.zero?
+        parse_header row
+      else
+        yield parse_bike(row)
+      end
+    end
+  end
+
+  def parse_header(row)
+    @header = row
+  end
+
+  def parse_bike(row)
+    @header.zip(row).to_h
+  end
+
+  def import_bike(bike_hash)
+    # TODO
+  end
+
+  def clean_value(value)
+    value_or_nil strip_value(value)
+  end
+
+  def strip_value(value)
+    value.try(:strip).try(:gsub, /\n|\r/, '')
+  end
+
+  def value_or_nil(value)
+    return value unless ['?', 'n/a', 'missing', ''].include? value.try(:downcase)
+  end
+end

lib/tasks/import.rake

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+namespace :import do
+  namespace :bikes do
+    # Imports bikes info from CSV file
+    task :csv, [:file] => :environment do |t, args|
+      file = args[:file]
+      next puts "Usage: rake #{t.name}[$csv_file_path]" unless file
+      next puts "File #{file} does not exist or is unreachable" unless File.readable? file
+      pp BikesCsvImporter.new(file).run
+    end
+
+    # Analyze a single field from CSV file
+    task :analyze_csv, [:file, :field] => :environment do |t, args|
+      file, field = args.values_at :file, :field
+      next puts "Usage: rake #{t.name}[$csv_file_path[,\"$field_name\"]]" unless file
+      next puts "File #{file} does not exist or is unreachable" unless File.readable? file
+      pp BikesCsvImporter.new(file).analyze field ? [field] : []
+    end
+  end
+end