Where is the documentation page for ActiveRecord data types?

I can't find the active record documenation page that has a list of all the data types.

Can someone help me out?

If you're talking about the types for migrations, e.g. string, integer, datetime, etc, then you want ActiveRecord::ConnectionAdapters::TableDefinition, the column method. (Rails 5 edit: see also connection.add_column.)

As of this update, the standard types are:

• :primary_key
• :string
• :text
• :integer
• :bigint
• :float
• :decimal
• :numeric
• :datetime
• :time
• :date
• :binary
• :boolean

The implementation of :decimal is different with each database, so I'd avoid it if possible. You may use a type not in this list as long as it is supported by your database (for example, :polygon in MySQL), but this will not be database agnostic and should also be avoided.

You can also see ActiveRecord data types in sources. Each DBMS adapter contains its own mapping. For example, in MySQL case look at this file: https://github.com/rails/rails/blob/master/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb#L148 or get it by this line of code for current DBMS adapter:

ActiveRecord::Base.connection.native_database_types.keys

Here is the default mappings of types for database adapters: