如何在rails 5中使用attach gem

我的环境:

• Ruby 2.4.1
• 钢轨5.1.4

我正在尝试使用附件gem,它是由写这篇文章的人写的 https://atech.blog/atech/file-attachments-in-rails-tutorial .

当我运行bundle install时,它会安装attach gem,版本1.0.2

然后,当我尝试运行rake命令时,我得到一个错误,表示它不知道如何构建任务。

rake attach:install:migrations --trace

rake aborted!
Don't know how to build task 'attach:install:migrations' (see --tasks)
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/task_manager.rb:59:in `[]'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/application.rb:159:in `invoke_task'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/application.rb:116:in `block (2 levels) in top_level'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/application.rb:116:in `each'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/application.rb:116:in `block in top_level'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/application.rb:125:in `run_with_threads'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/application.rb:110:in `top_level'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/application.rb:83:in `block in run'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/application.rb:186:in `standard_exception_handling'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/lib/rake/application.rb:80:in `run'
/usr/local/rvm/gems/ruby-2.4.1/gems/rake-12.3.0/exe/rake:27:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.4.1/bin/rake:23:in `load'
/usr/local/rvm/gems/ruby-2.4.1/bin/rake:23:in `<main>'
/usr/local/rvm/gems/ruby-2.4.1/bin/ruby_executable_hooks:15:in `eval'
/usr/local/rvm/gems/ruby-2.4.1/bin/ruby_executable_hooks:15:in `<main>'

你知道错误是什么吗?我想知道我是否错过了一个必要的宝石,使其工作。附加文档的链接为 https://github.com/adamcooke/attach