原创作者: hideto   阅读:1859次   评论:0条   更新时间:2011-05-26    
来看看怎样写自己的Generator吧

首先运行:
ruby script/generate

console中的输出可以看到Rails默认的generate:
Installed Generators
  Builtin: controller, integration_test, mailer, migration, model, observer, plugin, resource, scaffold,
scaffold_resource, session_migration, web_service

我们创建本机的generators目录:
mkdir -p ~/.rails/generators/app_layout

或者在某个rails项目里创建私有的generators:
mkdir -p /Users/demo/rails/simple/generators/app_layout


Generators有带参数和不带参数两种,先来看不带参数的Generator:
app_layout
--app_layout_generator.rb
--USAGE
  templates
----stylesheet.css
----layout.rhtml

我们看看不带参数的Generator的写法:
class AppLayoutGenerator < Rails::Generator::Base
  def manifest
    record do |m|
      m.file "layout.rhtml", "app/views/layouts/application.rhtml"
      m.file "stylesheet.css", "public/stylesheets/application.css"
    end
  end
end

我们的AppLayoutGenerator继承与Rails::Generator::Base,它的功能相当于cp layout.rhtml和stylesheet.css到后面的文件

我们再运行ruby script/generate看看:
Installed Generators
  User: app_layout
  Builtin: controller, integration_test, mailer, migration, model, observer, plugin, resource, scaffold,
scaffold_resource, session_migration, web_service

OK,我们看到除了Builtin的Generators,我们刚才创建的本机的app_layout这个Generator也出现在User Generators里

我们这样来使用它:
ruby script/generate app_layout

我们看到console打印出如下信息:
    create app/views/layouts/application.rhtml
    create public/stylesheets/application.css

系统自动创建了上面两个文件,内容为我们的app_layout/templates目录下的两个文件

如果我们想使用ruby script/generate app_layout home这样的方式,用home参数来指定创建home.rhtml和home.css,
我们该怎样写我们的Generator呢?
答案是继承Rails::Generator::NamedBase
class AppLayoutGenerator < Rails::Generator::NamedBase
  def manifest
    record do |m|
      m.template "layout.rhtml", "app/views/layouts/#{file_name}.rhtml"
      m.file "stylesheet.css", "public/stylesheets/#{file_name}.css"
    end
  end
end

除了使用m.template,我们还要修改layout.rhtml:
<html>
  <head>
    <title>Untitled</title>
    <%%= stylesheet_link_tag '<%= file_name %>' %>
    <%%= javascript_include_tag :defaults %>
  </head>
  <body>
    <div id="container">
      <%% flash.each do |name, msg| %>
        <%%= content_tag :div, msg, :id => "flash_#{name}" %>
      <%% end %>
      <%%= yield %>
    </div>
  </body>
</html>

这里的template使用<%% %>而不是<% %>
我们可以看看Rails源码/railties/lib/rails_generator/generators/components/scaffold/templates/layout.html.erb:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
       "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
  <meta http-equiv="content-type" content="text/html;charset=UTF-8" />
  <title><%= controller_class_name %>: <%%= controller.action_name %></title>
  <%%= stylesheet_link_tag 'scaffold' %>
</head>
<body>

<p style="color: green"><%%= flash[:notice] %></p>

<%%= yield  %>

</body>
</html>
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