Contents

# frozen_string_literal: true
require_relative "./active_record_cursor"
module JobIteration
  # Builds Enumerator based on ActiveRecord Relation. Supports enumerating on rows and batches.
  # @see EnumeratorBuilder
  class ActiveRecordEnumerator
    def initialize(relation, columns: nil, batch_size: 100, cursor: nil)
      @relation = relation
      @batch_size = batch_size
      @columns = Array(columns || "#{relation.table_name}.#{relation.primary_key}")
      @cursor = cursor
    end

    def records
      Enumerator.new(method(:size)) do |yielder|
        batches.each do |batch, _|
          batch.each do |record|
            yielder.yield(record, cursor_value(record))
          end
        end
      end
    end

    def batches
      cursor = finder_cursor
      Enumerator.new(method(:size)) do |yielder|
        while records = cursor.next_batch(@batch_size)
          yielder.yield(records, cursor_value(records.last)) if records.any?
        end
      end
    end

    def size
      @relation.count
    end

    private

    def cursor_value(record)
      positions = @columns.map do |column|
        method = column.to_s.split('.').last
        attribute = record.read_attribute(method.to_sym)
        attribute.is_a?(Time) ? attribute.to_s(:db) : attribute
      end
      return positions.first if positions.size == 1
      positions
    end

    def finder_cursor
      JobIteration::ActiveRecordCursor.new(@relation, @columns, @cursor)
    end
  end
end

Version data entries

8 entries across 8 versions & 1 rubygems

Version	Path
job-iteration-0.9.8	lib/job-iteration/active_record_enumerator.rb
job-iteration-0.9.7	lib/job-iteration/active_record_enumerator.rb
job-iteration-0.9.6	lib/job-iteration/active_record_enumerator.rb
job-iteration-0.9.5	lib/job-iteration/active_record_enumerator.rb
job-iteration-0.9.4	lib/job-iteration/active_record_enumerator.rb
job-iteration-0.9.3	lib/job-iteration/active_record_enumerator.rb
job-iteration-0.9.2	lib/job-iteration/active_record_enumerator.rb
job-iteration-0.9.1	lib/job-iteration/active_record_enumerator.rb