Class: AddNumberColumnToRecorderRevisions

Inherits:
ActiveRecord::Migration
  • Object
show all
Defined in:
lib/generators/recorder/templates/add_number_column_to_recorder_revisions.rb

Overview

This migration adds number column to the ‘revisions` table.

Instance Method Summary collapse

Instance Method Details

#down ⇒ Object 



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# File 'lib/generators/recorder/templates/add_number_column_to_recorder_revisions.rb', line 31

def down
  execute <<-SQL
    DROP TRIGGER update_recorder_revisions_number;
  SQL

  execute <<-SQL
    DROP FUNCTION IF EXISTS get_recorder_revisions_number;
  SQL

  remove_column :recorder_revisions, :number
end

#up ⇒ Object 



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# File 'lib/generators/recorder/templates/add_number_column_to_recorder_revisions.rb', line 3

def up
  add_column :recorder_revisions, :number, :integer, :null => false, :default => 0

  execute <<-SQL
CREATE OR REPLACE FUNCTION get_recorder_revisions_number()
RETURNS trigger AS
$BODY$
BEGIN
  SELECT COALESCE(MAX(recorder_revisions.number), 0) + 1
  INTO NEW.number
  FROM
    recorder_revisions
  WHERE
    recorder_revisions.item_type = NEW.item_type
    AND recorder_revisions.item_id = NEW.item_id;

  RETURN NEW;
END;
$BODY$ LANGUAGE plpgsql;
  SQL

  execute <<-SQL
CREATE TRIGGER update_recorder_revisions_number
BEFORE INSERT ON recorder_revisions FOR EACH ROW
EXECUTE PROCEDURE get_recorder_revisions_number();
  SQL
end