As a default in the model class MyModel < Sry::Struct attribute :created_at, ::Types::Strict::Time.default(-> _ { Time.now }.freeze) # attribute :created_at, ::Types::Strict::Time.default(Proc.new { Time.now }.freeze) # attribute :created_at, ::Types::Strict::Time.default(lambda { |_| Time.now }.freeze) end Or in the database: db.create_table table_name do DateTime :created_at, null: false, default: Sequel.lit('CURRENT_TIMESTAMP') end class MyModel < Sry::Struct attribute :created_at, ::Types::Strict::Time.meta(omittable: true) end