Class: Sequel::MigrationReverser

Inherits:
BasicObject
Defined in:
lib/sequel/extensions/pg_enum.rb,
lib/sequel/extensions/migration.rb

Overview

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

Instance Method Summary collapse

Constructor Details

#initialize ⇒ MigrationReverser

Returns a new instance of MigrationReverser.



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# File 'lib/sequel/extensions/migration.rb', line 181

def initialize
  @actions = []
end

Instance Method Details

#reverse(&block) ⇒ Object

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.



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# File 'lib/sequel/extensions/migration.rb', line 188

def reverse(&block)
  instance_exec(&block)
rescue NoMethodError => e
  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"}
rescue => e
  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"}
else
  actions = @actions.reverse
  Proc.new do
   actions.each do |a|
    pr = a.last.is_a?(Proc) ? a.pop : nil
    # Allow calling private methods as the reversing methods are private
    send(*a, &pr)
   end
  end
end