Table

Dynamoid has some sensible defaults for you when you create a new table, including the table name and the primary key column. But you can change those if you like on table creation.

class User
  include Dynamoid::Document

  table name: :awesome_users, key: :user_id, read_capacity: 5, write_capacity: 5
end

These fields will not change an existing table: so specifying a new read_capacity and write_capacity here only works correctly for entirely new tables. Similarly, while Dynamoid will look for a table named awesome_users in your namespace, it won’t change any existing tables to use that name; and if it does find a table with the correct name, it won’t change its hash key, which it expects will be user_id. If this table doesn’t exist yet, however, Dynamoid will create it with these options.

There is basic support for DynamoDB’s Time To Live (TTL) mechanism. If you declare a field as a TTL field - it will be initialized if it doesn’t have a value yet. Default value is current time + specified seconds.

class User
  include Dynamoid::Document

  table expires: { field: :ttl, after: 60 }

  field :ttl, :integer
end

Field used to store expiration time (e.g. ttl) should be declared explicitly and should have numeric type (integer, number) only. datetime type is also possible but only if it’s stored as number (there is a way to store time as a string also).

It’s also possible to override a global option Dynamoid::Config.timestamps on a table level:

table timestamps: false

This option controls generation of timestamp fields created_at/updated_at.

It’s also possible to override table capacity mode configured globally with table level option capacity_mode. Valid values are :provisioned, :on_demand and nil:

table capacity_mode: :on_demand

If table capacity mode is on-demand, another related table-level options read_capacity and write_capacity will be ignored.