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Allow reverting of migration commands with Migration#revert

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1 parent f460835 commit c76762dca20950b06a9ad5aa981076939ab9d711 @marcandre committed Aug 7, 2012
@@ -373,22 +373,52 @@ def initialize(name = self.class.name, version = nil)
@name = name
@version = version
@connection = nil
- @reverting = false
end
# instantiate the delegate object after initialize is defined
self.verbose = true
self.delegate = new
+ # Reverses the migration commands for the given block.
+ #
+ # The following migration will remove the table 'horses'
+ # and create the table 'apples' on the way up, and the reverse
+ # on the way down.
+ #
+ # class FixTLMigration < ActiveRecord::Migration
+ # def change
+ # revert do
+ # create_table(:horses) do |t|
+ # t.text :content
+ # t.datetime :remind_at
+ # end
+ # end
+ # create_table(:apples) do |t|
+ # t.string :variety
+ # end
+ # end
+ # end
+ #
+ # This command can be nested.
+ #
def revert
- @reverting = true
- yield
- ensure
- @reverting = false
+ if @connection.respond_to? :revert
+ @connection.revert { yield }
+ else
+ recorder = CommandRecorder.new(@connection)
+ @connection = recorder
+ suppress_messages do
+ @connection.revert { yield }
+ end
+ @connection = recorder.delegate
+ recorder.commands.each do |cmd, args, block|
+ send(cmd, *args, &block)
+ end
+ end
end
def reverting?
- @reverting
+ @connection.respond_to?(:reverting) && @connection.reverting
end
def up
@@ -414,29 +444,19 @@ def migrate(direction)
time = nil
ActiveRecord::Base.connection_pool.with_connection do |conn|
- @connection = conn
- if respond_to?(:change)
- if direction == :down
- recorder = CommandRecorder.new(@connection)
- suppress_messages do
- @connection = recorder
+ time = Benchmark.measure do
+ @connection = conn
+ if respond_to?(:change)
+ if direction == :down
+ revert { change }
+ else
change
end
- @connection = conn
- time = Benchmark.measure {
- self.revert {
- recorder.inverse.each do |cmd, args|
- send(cmd, *args)
- end
- }
- }
else
- time = Benchmark.measure { change }
+ send(direction)
end
- else
- time = Benchmark.measure { send(direction) }
+ @connection = nil
end
- @connection = nil
end
case direction
@@ -483,7 +503,7 @@ def method_missing(method, *arguments, &block)
arg_list = arguments.map{ |a| a.inspect } * ', '
say_with_time "#{method}(#{arg_list})" do
- unless reverting?
+ unless @connection.respond_to? :revert
unless arguments.empty? || method == :execute
arguments[0] = Migrator.proper_table_name(arguments.first)
arguments[1] = Migrator.proper_table_name(arguments.second) if method == :rename_table
@@ -16,35 +16,54 @@ class Migration
class CommandRecorder
include JoinTable
- attr_accessor :commands, :delegate
+ attr_accessor :commands, :delegate, :reverting
def initialize(delegate = nil)
@commands = []
@delegate = delegate
+ @reverting = false
+ end
+
+ # While executing the given block, the recorded will be in reverting mode.
+ # All commands recorded will end up being recorded reverted
+ # and in reverse order.
+ # For example:
+ #
+ # recorder.revert{ recorder.record(:rename_table, [:old, :new]) }
+ # # same effect as recorder.record(:rename_table, [:new, :old])
+ def revert
+ @reverting = !@reverting
+ previous = @commands
+ @commands = []
+ yield
+ ensure
+ @commands = previous.concat(@commands.reverse)
+ @reverting = !@reverting
end
# record +command+. +command+ should be a method name and arguments.
# For example:
#
# recorder.record(:method_name, [:arg1, :arg2])
- def record(*command)
- @commands << command
+ def record(*command, &block)
+ if @reverting
+ @commands << inverse_of(*command, &block)
+ else
+ @commands << (command << block)
+ end
end
- # Returns a list that represents commands that are the inverse of the
- # commands stored in +commands+. For example:
+ # Returns the inverse of the given command. For example:
#
- # recorder.record(:rename_table, [:old, :new])
- # recorder.inverse # => [:rename_table, [:new, :old]]
+ # recorder.inverse_of(:rename_table, [:old, :new])
+ # # => [:rename_table, [:new, :old]]
#
# This method will raise an +IrreversibleMigration+ exception if it cannot
- # invert the +commands+.
- def inverse
- @commands.reverse.map { |name, args|
- method = :"invert_#{name}"
- raise IrreversibleMigration unless respond_to?(method, true)
- send(method, args)
- }
+ # invert the +command+.
+ def inverse_of(command, args, &block)
+ method = :"invert_#{command}"
+ raise IrreversibleMigration unless respond_to?(method, true)
+ send(method, args, &block)
end
def respond_to?(*args) # :nodoc:
@@ -53,9 +72,9 @@ def respond_to?(*args) # :nodoc:
[:create_table, :create_join_table, :change_table, :rename_table, :add_column, :remove_column, :rename_index, :rename_column, :add_index, :remove_index, :add_timestamps, :remove_timestamps, :change_column, :change_column_default, :add_reference, :remove_reference].each do |method|
class_eval <<-EOV, __FILE__, __LINE__ + 1
- def #{method}(*args) # def create_table(*args)
- record(:"#{method}", args) # record(:create_table, args)
- end # end
+ def #{method}(*args, &block) # def create_table(*args, &block)
+ record(:"#{method}", args, &block) # record(:create_table, args, &block)
+ end # end
EOV
end
alias :add_belongs_to :add_reference
@@ -17,6 +17,17 @@ def change
end
end
+ class InvertibleRevertMigration < SilentMigration
+ def change
+ revert do
+ create_table("horses") do |t|
+ t.column :content, :text
+ t.column :remind_at, :datetime
+ end
+ end
+ end
+ end
+
class NonInvertibleMigration < SilentMigration
def change
create_table("horses") do |t|
@@ -67,6 +78,18 @@ def test_migrate_down
assert !migration.connection.table_exists?("horses")
end
+ def test_migrate_revert
+ migration = InvertibleMigration.new
+ revert = InvertibleRevertMigration.new
+ migration.migrate :up
+ revert.migrate :up
+ assert !migration.connection.table_exists?("horses")
+ revert.migrate :down
+ assert migration.connection.table_exists?("horses")
+ migration.migrate :down
+ assert !migration.connection.table_exists?("horses")
+ end
+
def test_legacy_up
LegacyMigration.migrate :up
assert ActiveRecord::Base.connection.table_exists?("horses"), "horses should exist"
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