rake db:migrate 用法示例

先占个位置，近来一直用migrate，准备写一个关于这个的总结。
收集资料先

AppleMan的六篇总结
运行rake db:migrate的时候从fixture里加载
相当于手动的命令

FIXTURES=config_params RAILS_ENV=production /usr/bin/rake db:YAML:restore

class InitConfig < ActiveRecord::Migration
  def self.up
    require 'rake'
    rake = Rake::Application.new
    ENV['FIXTURES'] = "config_params"
    Rake::Task["db:YAML:restore"].invoke
  end

  def self.down
    ConfigParam.delete_all()
  end
end

实体完成性约束

class AddUniqueSiteProfile < ActiveRecord::Migration
  def self.up
    change_column("sites", "name", :string,:null => false )
    change_column("profiles", "name", :string,:length =>50, :null => false)
    add_index(:sites,[:name],:unique=>true)
    add_index(:profiles,[:name],:unique=>true)
  end

  def self.down
    change_column("sites","name",:string)
    change_column("profiles","name", :string, :length => 50)
    remove_index(:sites,:column=>:name)
    remove_index(:profiles,:column=>:name)
  end
end

增加一个字段并且添加一个值

class AddRegionIdToAnalyzer < ActiveRecord::Migration
  def self.up
    add_column :analyzers, :region_id, :integer,:default => 1
    Analyzer.find(:all).each { |a|
      a.region_id=1
      a.save
    }
  end

  def self.down
    remove_column :analyzers, :region_id
  end
end

添加索引

  def self.up
    add_index "measurements", ["site_id","measure_id","channel_id", "dt"],:name => "meas_idx"
    add_column "measures", "graph_flag", :boolean, :default => true
  end

  def self.down
    remove_index "measurements",:name => "meas_idx"
    remove_column "measures", "graph_flag"
  end