vendor/rails/activerecord/lib/active_record/schema.rb

   1 module ActiveRecord
   2   # Allows programmers to programmatically define a schema in a portable
   3   # DSL. This means you can define tables, indexes, etc. without using SQL
   4   # directly, so your applications can more easily support multiple
   5   # databases.
   6   #
   7   # Usage:
   8   #
   9   #   ActiveRecord::Schema.define do
  10   #     create_table :authors do |t|
  11   #       t.string :name, :null => false
  12   #     end
  13   #
  14   #     add_index :authors, :name, :unique
  15   #
  16   #     create_table :posts do |t|
  17   #       t.integer :author_id, :null => false
  18   #       t.string :subject
  19   #       t.text :body
  20   #       t.boolean :private, :default => false
  21   #     end
  22   #
  23   #     add_index :posts, :author_id
  24   #   end
  25   #
  26   # ActiveRecord::Schema is only supported by database adapters that also
  27   # support migrations, the two features being very similar.
  28   class Schema < Migration
  29     private_class_method :new
  30
  31     # Eval the given block. All methods available to the current connection
  32     # adapter are available within the block, so you can easily use the
  33     # database definition DSL to build up your schema (+create_table+,
  34     # +add_index+, etc.).
  35     #
  36     # The +info+ hash is optional, and if given is used to define metadata
  37     # about the current schema (currently, only the schema's version):
  38     #
  39     #   ActiveRecord::Schema.define(:version => 20380119000001) do
  40     #     ...
  41     #   end
  42     def self.define(info={}, &block)
  43       instance_eval(&block)
  44
  45       unless info[:version].blank?
  46         initialize_schema_migrations_table
  47         assume_migrated_upto_version info[:version]
  48       end
  49     end
  50   end
  51 end