ruby-on-rails – 每当gem schedule.rb文件：不重写RAILS_ROOT变量

在schedule.rb文件中,语句为：

require "#{RAILS_ROOT}/config/environment.rb"

 every "10 10 2 * * *" do
      command "MysqLdump -u #{@db_username} -p#{@db_password} --single-transaction #{@db_name} > #{@backup_Path}/#{@db_name}.sql 2> log/error_crontab.log"
 end

当我尝试从终端执行每个cmd时,得到以下错误：

config/schedule.rb:48:in `initialize': uninitialized constant Whenever::JobList::RAILS_ROOT (NameError)
    from /usr/local/lib/ruby/gems/1.9.1/gems/whenever-0.7.0/lib/whenever/job_list.rb:19:in `instance_eval'
    from /usr/local/lib/ruby/gems/1.9.1/gems/whenever-0.7.0/lib/whenever/job_list.rb:19:in `initialize'
    from /usr/local/lib/ruby/gems/1.9.1/gems/whenever-0.7.0/lib/whenever.rb:16:in `new'
    from /usr/local/lib/ruby/gems/1.9.1/gems/whenever-0.7.0/lib/whenever.rb:16:in `cron'
    from /usr/local/lib/ruby/gems/1.9.1/gems/whenever-0.7.0/lib/whenever/command_line.rb:40:in `run'
    from /usr/local/lib/ruby/gems/1.9.1/gems/whenever-0.7.0/lib/whenever/command_line.rb:7:in `execute'
    from /usr/local/lib/ruby/gems/1.9.1/gems/whenever-0.7.0/bin/whenever:38:in `<top (required)>'
    from /usr/local/bin/whenever:19:in `load'
    from /usr/local/bin/whenever:19:in `<main>'

我正在使用require语句从窗体获取动态值来计划作业.请帮忙解决这个问题？

注意：我已经看到以下stackoverflow查询：
How to detect Rails environment inside whenever

以下这个线程得到动态值,但面临的问题与require语句.
Rails – Whenever gem – Dynamic values

Ruby/Rails – Whenever gem – Loop cron tasks

config file in schedule.rb with Rails Whenever gem?

谢谢,
Sudhir C.N.

解决方法

每当不需要或依赖于Rails,所以运行时,RAILS_ROOT没有定义,但是由于schedule.rb通常保存在/config/schedule.rb中,所以我们可以假设它是在一个rails项目,并设置我们自己的RAILS_ROOT像这样：

# in schedule.rb
RAILS_ROOT = File.dirname(__FILE__) + '/..'

编辑：在您实际需要加载Rails的情况下,请执行以下操作：

# in schedule.rb
# this will require config/environment and load your entire rails environment
require File.expand_path(File.dirname(__FILE__) + "/environment")