module ActiveRecord
# = Active Record Schema
#
# 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.string :name, null: false
# end
#
# add_index :authors, :name, :unique
#
# create_table :posts do |t|
# t.integer :author_id, null: false
# t.string :subject
# t.text :body
# t.boolean :private, 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 Schema < Migration
# 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 (currently, only the schema's version):
#
# ActiveRecord::Schema.define(version: 20380119000001) do
# ...
# end
def self.define(info={}, &block)
new.define(info, &block)
end
def define(info, &block) # :nodoc:
instance_eval(&block)
if info[:version].present?
initialize_schema_migrations_table
connection.assume_migrated_upto_version(info[:version], migrations_paths)
end
end
private
# Returns the migrations paths.
#
# ActiveRecord::Schema.new.migrations_paths
# # => ["db/migrate"] # Rails migration path by default.
def migrations_paths # :nodoc:
ActiveRecord::Migrator.migrations_paths
end
end
end
