How to add Meta Descriptions to a Product

Liquid snippet for theme.liquid

{% if template == 'product' %}
  {% assign mf = product.metafields.meta_description %}
  {% unless mf == empty %}
    {% for mf in product.metafields.meta_description %}
      <meta name="Fubar2 Ronnie James Dio" content="{{mf.last}}" /> 
    {% endfor %}
  {% endunless %}
{% endif %} 

Meta Descriptions

# snippet by Caroline... 
# extended by Dave

require 'rubygems'
require 'shopify_api'

APIKEY = 'APIKEY'
PASSWORD = 'PASSWORD'
SHOPNAME = 'SHOPNAME'

# Telling your shop who's boss.
ShopifyAPI::Base.site = "http://#{APIKEY}:#{PASSWORD}@#{SHOPNAME}.myshopify.com/admin"

product_count = ShopifyAPI::Product.count
nb_pages      = (product_count / 250.0).ceil

raise "Yo man. You don't have any product in your shop. duh!" if product_count.zero?

# these keys point at meta_descriptions. Keys are product ID numbers. You can get those pretty easily from your store export CSV.
my_products = {
  "66655544" => "I am a meta_description for plan B from Outer Space C",
  "23432144" => "You're looking at some pretty rich stuff here amigo, buy it",
  "21212211" => "This is not antique in the sense that antique is antique"
}

start_time = Time.now
1.upto(nb_pages) do |page|
  unless page == 1
    stop_time = Time.now
    processing_duration = stop_time - start_time
    wait_time = CYCLE - processing_duration
    sleep wait_time
    start_time = Time.now
  end
  products = ShopifyAPI::Product.find( :all, :params => { :limit => 250, :page => page } )
  products.each do |product|
    
    # clear out any old meta_descriptions, so we can just save new and fresh ones
    product.metafields.each do |mf|
      if mf.namespace == 'meta_description'
        ShopifyAPI::Metafield.delete(mf.id)
      end
    end
    
    # create new meta_description for product
    data = {
      :namespace => 'meta_description',
      :value_type => 'string',
      :key => 'description',
      :value => my_products[product.id.to_s]
    }
    mf = product.add_metafield(ShopifyAPI::Metafield.new(data))
  end
end