Class: Sequel::MigrationReverser

Inherits:
BasicObject
Defined in:
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.

Constant Summary

Constants inherited from BasicObject

BasicObject::KEEP_METHODS

Instance Method Summary collapse

Methods inherited from BasicObject

const_missing, remove_methods!

Constructor Details

#initialize ⇒ MigrationReverser

Returns a new instance of MigrationReverser.



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# File 'lib/sequel/extensions/migration.rb', line 125

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 132

def reverse(&block)
  begin
    instance_eval(&block)
  rescue
    just_raise = true
  end
  if just_raise
    Proc.new{raise Sequel::Error, 'irreversible migration method used, you may need to write your own down method'}
  else
    actions = @actions.reverse
    Proc.new do
      actions.each do |a|
        if a.last.is_a?(Proc)
          pr = a.pop
          send(*a, &pr)
        else
          send(*a)
        end
      end
    end
  end
end