ActiveRecord::ConnectionAdapters::ColumnMethods
Methods
P
Instance Public methods
primary_key(name, type = :primary_key, **options)

Appends a primary key definition to the table definition. Can be called multiple times, but this is probably not a good idea.

Source: show | on GitHub 

# File activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb, line 161
def primary_key(name, type = :primary_key, **options)
  column(name, type, options.merge(primary_key: true))
end