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

Methods inherited from BasicObject

const_missing

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