Module: Moped::Scrollable

Defined in:
lib/moped/scrollable.rb

Instance Method Summary collapse

Instance Method Details

#scroll(cursor = nil, options = nil, &_block) ⇒ Object 



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# File 'lib/moped/scrollable.rb', line 3

def scroll(cursor = nil, options = nil, &_block)
  unless options
    bson_type = Mongoid::Compatibility::Version.mongoid3? ? Moped::BSON::ObjectId : BSON::ObjectId
    options = { field_type: bson_type }
  end
  query = Query.new(collection, operation.selector.dup)
  query.operation.skip = operation.skip
  query.operation.limit = operation.limit
  # we don't support scrolling over a criteria with multiple fields
  if query.operation.selector['$orderby'] && query.operation.selector['$orderby'].keys.size != 1
    raise Mongoid::Scroll::Errors::MultipleSortFieldsError.new(sort: query.operation.selector['$orderby'])
  elsif !query.operation.selector.key?('$orderby') || query.operation.selector['$orderby'].empty?
    # introduce a default sort order if there's none
    query.sort(_id: 1)
  end
  # scroll field and direction
  scroll_field = query.operation.selector['$orderby'].keys.first
  scroll_direction = query.operation.selector['$orderby'].values.first.to_i
  # scroll cursor from the parameter, with value and tiebreak_id
  cursor_options = { field_name: scroll_field, field_type: options[:field_type], direction: scroll_direction }
  cursor = cursor.is_a?(Mongoid::Scroll::Cursor) ? cursor : Mongoid::Scroll::Cursor.new(cursor, cursor_options)
  query.operation.selector['$query'] = query.operation.selector['$query'].merge(cursor.criteria)
  query.operation.selector['$orderby'] = query.operation.selector['$orderby'].merge(_id: scroll_direction)
  # scroll
  if block_given?
    query.each do |record|
      yield record, Mongoid::Scroll::Cursor.from_record(record, cursor_options)
    end
  else
    query
  end
end