has_many_improved.rb

class ActiveRecord::Associations::AssociationCollection
  def has_finder_sql_with_select?
    @finder_sql =~ /^\s*select\s/i
  end
  
  def find(*args)
    options = args.extract_options!

    # If using a custom finder_sql, scan the entire collection.
    if has_finder_sql_with_select?
      expects_array = args.first.kind_of?(Array)
      ids           = args.flatten.compact.uniq.map { |arg| arg.to_i }

      if ids.size == 1
        id = ids.first
        record = load_target.detect { |r| id == r.id }
        expects_array ? [ record ] : record
      else
        load_target.select { |r| ids.include?(r.id) }
      end
    else
      conditions = "#{@finder_sql}"
      if sanitized_conditions = sanitize_sql(options[:conditions])
        conditions << " AND (#{sanitized_conditions})"
      end
      
      options[:conditions] = conditions

      if options[:order] && @reflection.options[:order]
        options[:order] = "#{options[:order]}, #{@reflection.options[:order]}"
      elsif @reflection.options[:order]
        options[:order] = @reflection.options[:order]
      end
      
      # Build options specific to association
      construct_find_options!(options)
      
      merge_options_from_reflection!(options)
      
      # Pass through args exactly as we received them.
      args << options
      @reflection.klass.find(*args)
    end
  end

  def find_target
    records =
      if has_finder_sql_with_select?
        @reflection.klass.find_by_sql(@finder_sql)
      else
        find(:all)
      end

    records = @reflection.options[:uniq] ? uniq(records) : records
    records.each do |record|
      set_inverse_instance(record, @owner)
    end
    records
  end
  
  def fetch_first_or_last_using_find?(args)
    args.first.kind_of?(Hash) || 
      !(loaded? || @owner.new_record? || has_finder_sql_with_select? ||
        @target.any? { |record| record.new_record? } || args.first.kind_of?(Integer))
  end
end

class ActiveRecord::Associations::HasManyAssociation
  def construct_sql
    case
      when @reflection.options[:finder_sql]
        @finder_sql = interpolate_sql(@reflection.options[:finder_sql])

      when @reflection.options[:as]
        @finder_sql = 
          "#{@reflection.quoted_table_name}.#{@reflection.options[:as]}_id = #{owner_quoted_id} AND " +
          "#{@reflection.quoted_table_name}.#{@reflection.options[:as]}_type = #{@owner.class.quote_value(@owner.class.base_class.name.to_s)}"
        @finder_sql << " AND (#{conditions})" if conditions
      
      else
        @finder_sql = "#{@reflection.quoted_table_name}.#{@reflection.primary_key_name} = #{owner_quoted_id}"
        @finder_sql << " AND (#{conditions})" if conditions
    end

    if @reflection.options[:counter_sql]
      @counter_sql = interpolate_sql(@reflection.options[:counter_sql])
    elsif has_finder_sql_with_select?
      # replace the SELECT clause with COUNT(*), preserving any hints within /* ... */
      @reflection.options[:counter_sql] = @reflection.options[:finder_sql].sub(/SELECT (\/\*.*?\*\/ )?(.*)\bFROM\b/im) { "SELECT #{$1}COUNT(*) FROM" }
      @counter_sql = interpolate_sql(@reflection.options[:counter_sql])
    else
      @counter_sql = @finder_sql
    end
  end
end