Class: ActiveRecord::Schema

Inherits:
Migration show all
Defined in:
lib/active_record/schema.rb

Overview

Allows programmers to programmatically define a schema in a portable DSL. This means you can define tables, indexes, etc. without using SQL directly, so your applications can more easily support multiple databases.

Usage:

ActiveRecord::Schema.define do
  create_table :authors do |t|
    t.column :name, :string, :null => false
  end

  add_index :authors, :name, :unique

  create_table :posts do |t|
    t.column :author_id, :integer, :null => false
    t.column :subject, :string
    t.column :body, :text
    t.column :private, :boolean, :default => false
  end

  add_index :posts, :author_id
end

ActiveRecord::Schema is only supported by database adapters that also support migrations, the two features being very similar.

Class Method Summary collapse

Methods inherited from Migration

announce, down_using_benchmarks, method_missing, migrate, say, say_with_time, singleton_method_added, suppress_messages, up_using_benchmarks, write

Class Method Details

.define(info = {}, &block) ⇒ Object

Eval the given block. All methods available to the current connection adapter are available within the block, so you can easily use the database definition DSL to build up your schema (#create_table, #add_index, etc.).

The info hash is optional, and if given is used to define metadata about the current schema (like the schema’s version):

ActiveRecord::Schema.define(:version => 15) do
  ...
end



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# File 'lib/active_record/schema.rb', line 42

def self.define(info={}, &block)
  instance_eval(&block)

  unless info.empty?
    initialize_schema_information
    cols = columns('schema_info')

    info = info.map do |k,v|
      v = Base.connection.quote(v, cols.detect { |c| c.name == k.to_s })
      "#{k} = #{v}"
    end

    Base.connection.update "UPDATE #{Migrator.schema_info_table_name} SET #{info.join(", ")}"
  end
end