Module: CompositePrimaryKeys::ActiveRecord::Batches

Defined in:
lib/composite_primary_keys/relation/batches.rb

Instance Method Summary collapse

Instance Method Details

#find_in_batches(options = {}) ⇒ Object 



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# File 'lib/composite_primary_keys/relation/batches.rb', line 4

def find_in_batches(options = {})
  relation = self

  unless arel.orders.blank? && arel.taken.blank?
    ::ActiveRecord::Base.logger.warn("Scoped order and limit are ignored, it's forced to be batch order and batch size")
  end

  if (finder_options = options.except(:start, :batch_size)).present?
    raise "You can't specify an order, it's forced to be #{batch_order}" if options[:order].present?
    raise "You can't specify a limit, it's forced to be the batch_size"  if options[:limit].present?

    relation = apply_finder_options(finder_options)
  end

  start = options.delete(:start).to_i
  batch_size = options.delete(:batch_size) || 1000

  relation = relation.reorder(batch_order).limit(batch_size)

  # CPK
  # records = relation.where(table[primary_key].gteq(start)).all
  records = self.primary_key.reduce(relation) do |rel, key|
    rel.where(table[key].gteq(start))
  end

  while records.any?
    records_size = records.size
    primary_key_offset = records.last.id

    yield records

    break if records_size < batch_size

    if primary_key_offset
      # CPK
      # Lexicographically select records
      #
      query = prefixes(primary_key.zip(primary_key_offset)).map do |kvs|
        and_clause = kvs.each_with_index.map do |(k, v), i|
          # Use > for the last key in the and clause
          # otherwise use =
          if i == kvs.length - 1
            table[k].gt(v)
          else
            table[k].eq(v)
          end
        end.reduce(:and)

        Arel::Nodes::Grouping.new(and_clause)
      end.reduce(:or)

      records = relation.where(query)
    else
      raise "Primary key not included in the custom select clause"
    end
  end
end