class Sequel::MigrationReverser

Handles the reversing of reversible migrations. Basically records supported methods calls, translates them to reversed calls, and returns them in reverse order.

:nocov:

Public Class Methods

new() click to toggle source

    # File lib/sequel/extensions/migration.rb
181 def initialize
182   @actions = []
183 end

Public Instance Methods

reverse(&block) click to toggle source

Reverse the actions for the given block. Takes the block given and returns a new block that reverses the actions taken by the given block.

    # File lib/sequel/extensions/migration.rb
188 def reverse(&block)
189   instance_exec(&block)
190 rescue NoMethodError => e
191   Proc.new{raise Sequel::Error, "irreversible migration method \"#{e.name}\" used in #{block.source_location.first}, you may need to write your own down method"}
192 rescue => e
193   Proc.new{raise Sequel::Error, "unable to reverse migration due to #{e.class} in #{block.source_location.first}, you may need to write your own down method"}
194 else
195   actions = @actions.reverse
196   Proc.new do
197    actions.each do |a|
198     pr = a.last.is_a?(Proc) ? a.pop : nil
199     # Allow calling private methods as the reversing methods are private
200     send(*a, &pr)
201    end
202   end
203 end

Private Instance Methods

add_column(*args) click to toggle source

    # File lib/sequel/extensions/migration.rb
207 def add_column(*args)
208   @actions << [:drop_column, args[0], args[1]]
209 end

add_index(*args) click to toggle source

    # File lib/sequel/extensions/migration.rb
211 def add_index(*args)
212   @actions << [:drop_index, *args]
213 end

alter_table(table, &block) click to toggle source

    # File lib/sequel/extensions/migration.rb
215 def alter_table(table, &block)
216   @actions << [:alter_table, table, MigrationAlterTableReverser.new.reverse(&block)]
217 end

create_enum(name, _) click to toggle source

    # File lib/sequel/extensions/pg_enum.rb
188 def create_enum(name, _)
189   @actions << [:drop_enum, name]
190 end

create_join_table(*args) click to toggle source

    # File lib/sequel/extensions/migration.rb
219 def create_join_table(*args)
220   @actions << [:drop_join_table, *args]
221 end

create_table(name, opts=OPTS, &_) click to toggle source

    # File lib/sequel/extensions/migration.rb
223 def create_table(name, opts=OPTS, &_)
224   @actions << [:drop_table, name, opts]
225 end

create_view(name, _, opts=OPTS) click to toggle source

    # File lib/sequel/extensions/migration.rb
227 def create_view(name, _, opts=OPTS)
228   @actions << [:drop_view, name, opts]
229 end

rename_column(table, name, new_name) click to toggle source

    # File lib/sequel/extensions/migration.rb
231 def rename_column(table, name, new_name)
232   @actions << [:rename_column, table, new_name, name]
233 end

rename_enum(old_name, new_name) click to toggle source

    # File lib/sequel/extensions/pg_enum.rb
192 def rename_enum(old_name, new_name)
193   @actions << [:rename_enum, new_name, old_name]
194 end

rename_table(table, new_name) click to toggle source

    # File lib/sequel/extensions/migration.rb
235 def rename_table(table, new_name)
236   @actions << [:rename_table, new_name, table]
237 end