create_on_duplicate_key_update

active_record.rb

module ActiveRecord
  # = Active Record Persistence
  module Persistence
    extend ActiveSupport::Concern

    def create_on_duplicate_key_update!(keys)
      #keys = duplicate_keys.is_a? Array ? duplicate_keys : [duplicate_keys] #TODO: 배열이 아닐때? 코드짜기.
      keys.collect! { |k| k.to_s }
      klass = self.class
      attributes_with_values = arel_attributes_with_values_for_create(attribute_names)
      column_hash = klass.connection.schema_cache.columns_hash klass.table_name
      db_columns_with_values = []
      attributes_with_values.map { |attr, value|
        real_column = column_hash[attr.name]
        db_columns_with_values << [real_column, value] if value.present?
        if (value.blank? && ['created_at', 'updated_at'].include?(real_column.name))
          now = DateTime.now
          db_columns_with_values << [real_column, now]
          self.send("#{attr.name}=",now)
        end
      }
      sql = "INSERT INTO #{self.class.quoted_table_name} (#{db_columns_with_values.collect{|c| klass.connection.quote_column_name(c.first.name)}.join(', ')})"
      sql << " VALUES (#{db_columns_with_values.collect{|c| klass.connection.quote(c.last)}.join(', ')}) "
      sql << " ON DUPLICATE KEY UPDATE "
      sql << sql_for_on_duplicate_key_update(keys,db_columns_with_values)

      klass.connection.execute sql
    end

    private
    def sql_for_on_duplicate_key_update(keys,db_columns_with_values)
      connection = self.class.connection
      results = []
      db_columns_with_values.map do |column, value|
        results << "#{self.class.quoted_table_name}.#{connection.quote_column_name(column.name)}=#{connection.quote(value, column)}" if (!keys.include?(column.name) && column.name != 'created_at')
      end
      results.join(',')
    end
  end
end