AWS SDK for Ruby
Developer Guide

Updating an Amazon DynamoDB Table Item

The following example updates the rating to 0.1 for the item with the year 2015 and title The Big New Movie in the Movies table in the us-west-2 region.

require 'aws-sdk-dynamodb' # v2: require 'aws-sdk' # Create dynamodb client in us-west-2 region dynamodb = 'us-west-2') params = { table_name: 'Movies', key: { year: 2015, title: 'The Big New Movie' }, update_expression: 'set info.rating = :r', expression_attribute_values: {':r' => 0.1}, return_values: 'UPDATED_NEW' } begin dynamodb.update_item(params) puts 'Rating successfully set' rescue Aws::DynamoDB::Errors::ServiceError => error puts 'Unable to set rating:' puts error.message end

See the complete example on GitHub.