Rails 3.1:引擎与可安装应用程序

Question

有人可以帮我理解Rails引擎和可安装应用程序之间的差异吗？在Rails 3.1中,您可以使用"rails new plugin _ __ "命令创建任一个.

rails plugin new forum --full        # Engine
rails plugin new forum --mountable   # Mountable App

你什么时候想要使用一个？我知道你可以将Engine打包成一个宝石.可安装应用程序的情况不是这样吗？还有什么其他差异？

Answer 1

我注意到以下几点:

全引擎

使用完整引擎,父应用程序将继承引擎的路由.没有必要指定任何内容parent_app/config/routes.rb.在Gemfile中指定gem足以让父应用程序继承模型,路由等.引擎路由指定为:

# my_engine/config/routes.rb 
Rails.application.routes.draw do 
  # whatever 
end 

没有模型,控制器等的命名空间.父应用程序可以立即访问这些命名空间.

可安装的发动机

默认情况下,引擎的命名空间是隔离的:

# my_engine/lib/my_engine/engine.rb
module MyEngine 
  class Engine < Rails::Engine 
    isolate_namespace MyEngine 
  end 
end

使用可安装引擎,路由是命名空间,父应用程序可以在单个路由下捆绑此功能:

# my_engine/config/routes.rb 
MyEngine::Engine.routes.draw do 
  #whatever 
end 

# parent_app/config/routes.rb 
ParentApp::Application.routes.draw do 
    mount MyEngine::Engine => "/engine", :as => "namespaced" 
end 

模型,控制器等与父应用程序隔离 - 尽管可以轻松共享帮助程序.

这些是我发现的主要差异.也许还有其他人？我在这里问过,但尚未收到回复.

我的印象是,由于完整引擎不会将自己与父应用程序隔离,因此最好将其用作与父应用程序相邻的独立应用程序.我相信名字冲突可能会发生.

可安装引擎可用于您希望避免名称冲突并将引擎捆绑在父应用程序中的一个特定路由下的情况.例如,我正在努力构建我的第一个专为客户服务而设计的引擎.父应用程序可以在单个路由下捆绑它的功能,例如:

mount Cornerstone::Engine => "/cornerstone", :as => "help" 

如果我在假设中离开,有人请告诉我,我会解决这个问题.我作出了关于这个问题的小文章,在这里 干杯!

Answer 2

这两个选项都会生成引擎.不同之处在于,--mountable它将在隔离的命名空间中--full创建引擎,而将创建一个共享主应用程序命名空间的引擎.

差异将以3种方式表现出来:

1)引擎类文件将调用isolate_namespace:

LIB/my_full_engine/engine.rb:

module MyFullEngine
  class Engine < Rails::Engine
  end
end

LIB/my_mountable_engine/engine.rb:

module MyMountableEngine
  class Engine < Rails::Engine
    isolate_namespace MyMountableEngine # --mountable option inserted this line
  end
end

2)引擎的config/routes.rb文件将被命名空间:

全发动机:

Rails.application.routes.draw do
end

已安装的发动机:

MyMountableEngine::Engine.routes.draw do
end

3)控制器,帮助程序,视图和资产的文件结构将被命名空间:

create app/controllers/my_mountable_engine /application_controller.rb
create app/helpers/my_mountable_engine /application_helper.rb
create app/mailers create app/models
create app/views/layouts/my_mountable_engine /application.html.erb
create app/assets/images/my_mountable_engine
create app/assets/stylesheets/my_mountable_engine /application.css
create app/assets/javascripts/my_mountable_engine /application.js
create config/routes.rb create lib/my_mountable_engine.rb
create lib/tasks/my_mountable_engine.rake
create lib/my_mountable_engine/version .RB
创建lib/my_mountable_engine/engine.rb

说明

该--full选项的用例似乎非常有限.就我个人而言,我想不出有什么理由可以将你的代码分离到一个引擎而不需要隔离命名空间 - 它本质上只会给你两个紧密耦合的应用程序共享相同的文件结构以及所有冲突和代码泄漏这需要.

每件文件我见过的演示--mountable选项,而事实上当前的边缘导向强烈建议您包括isolate namespace-这等于说使用--mountable了--full.

最后是术语混淆:不幸的是rails plugin -h显示以下描述:

[--full]#使用捆绑的Rails应用程序生成rails引擎进行测试
[--mountable]#生成可安装的隔离应用程序

这给人的印象是你--full用来创建一个"引擎"并--mountable创建一个叫做"可安装的应用程序"的东西,实际上它们都是引擎 - 一个是命名空间而一个不是.这肯定会导致混乱,因为寻求创建引擎的用户可能会认为这--full是更相关的选择.

结论

• rails plugin new something --full=应用程序命名空间中的引擎.(你为什么这么做？)
• rails plugin new something --mountable=引擎具有自己的命名空间.(真棒)

参考

• http://edgeguides.rubyonrails.org/engines.html
• http://api.rubyonrails.org/classes/Rails/Engine.html
• http://railscasts.com/episodes/277-mountable-engines
• https://github.com/rails/rails/pull/6499

Answer 3

我想知道同样的事情,因此,结束了.在我看来,早期的答案基本上涵盖了这个问题,但我认为以下内容也可能有所帮助:

# generate plugins (NOTE: using same name each time to minimize differences)
# -----------------------------------------------------------------------------

$ rails plugin new test-plugin -T
$ mv test-plugin{,.01}

$ rails plugin new test-plugin -T --mountable
$ mv test-plugin{,.02}

$ rails plugin new test-plugin -T --full
$ mv test-plugin{,.03}

$ rails plugin new test-plugin -T --full --mountable
$ mv test-plugin{,.04}




# compare "stock" (01) with "mountable" (02)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.01 test-plugin.02

Only in test-plugin.02: app
Only in test-plugin.02: config
Only in test-plugin.02/lib/test-plugin: engine.rb
diff -r test-plugin.01/lib/test-plugin.rb test-plugin.02/lib/test-plugin.rb
0a1,2
> require "test-plugin/engine"
> 
Only in test-plugin.02: script
diff -r test-plugin.01/test-plugin.gemspec test-plugin.02/test-plugin.gemspec
18a19
>   # s.add_dependency "jquery-rails"




# compare "stock" (01) with "full" (03)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.01 test-plugin.03
Only in test-plugin.03: app
Only in test-plugin.03: config
Only in test-plugin.03/lib/test-plugin: engine.rb
diff -r test-plugin.01/lib/test-plugin.rb test-plugin.03/lib/test-plugin.rb
0a1,2
> require "test-plugin/engine"
> 
Only in test-plugin.03: script
diff -r test-plugin.01/test-plugin.gemspec test-plugin.03/test-plugin.gemspec
18a19
>   # s.add_dependency "jquery-rails"




# compare "mountable" (02) with "full" (03)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.02 test-plugin.03

Only in test-plugin.03/app/assets/javascripts/test-plugin: .gitkeep
Only in test-plugin.02/app/assets/javascripts/test-plugin: application.js
Only in test-plugin.03/app/assets/stylesheets/test-plugin: .gitkeep
Only in test-plugin.02/app/assets/stylesheets/test-plugin: application.css
Only in test-plugin.03/app/controllers: .gitkeep
Only in test-plugin.02/app/controllers: test-plugin
Only in test-plugin.03/app/helpers: .gitkeep
Only in test-plugin.02/app/helpers: test-plugin
Only in test-plugin.03/app/mailers: .gitkeep
Only in test-plugin.03/app/models: .gitkeep
Only in test-plugin.03/app/views: .gitkeep
Only in test-plugin.02/app/views: layouts
diff -r test-plugin.02/config/routes.rb test-plugin.03/config/routes.rb
1c1
< TestPlugin::Engine.routes.draw do
---
> Rails.application.routes.draw do
diff -r test-plugin.02/lib/test-plugin/engine.rb test-plugin.03/lib/test-plugin/engine.rb
3d2
<     isolate_namespace TestPlugin




# compare "mountable" (02) with "full & mountable" (04)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.02 test-plugin.04

<no difference>




# compare "full" (03) with "full & mountable" (04)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.03 test-plugin.04

Only in test-plugin.03/app/assets/javascripts/test-plugin: .gitkeep
Only in test-plugin.04/app/assets/javascripts/test-plugin: application.js
Only in test-plugin.03/app/assets/stylesheets/test-plugin: .gitkeep
Only in test-plugin.04/app/assets/stylesheets/test-plugin: application.css
Only in test-plugin.03/app/controllers: .gitkeep
Only in test-plugin.04/app/controllers: test-plugin
Only in test-plugin.03/app/helpers: .gitkeep
Only in test-plugin.04/app/helpers: test-plugin
Only in test-plugin.03/app/mailers: .gitkeep
Only in test-plugin.03/app/models: .gitkeep
Only in test-plugin.03/app/views: .gitkeep
Only in test-plugin.04/app/views: layouts
diff -r test-plugin.03/config/routes.rb test-plugin.04/config/routes.rb
1c1
< Rails.application.routes.draw do
---
> TestPlugin::Engine.routes.draw do
diff -r test-plugin.03/lib/test-plugin/engine.rb test-plugin.04/lib/test-plugin/engine.rb
2a3
>     isolate_namespace TestPlugin

(对我来说)特别感兴趣的是,两者之间没有区别

rails plugin new test-plugin -T --mountable

和

rails plugin new test-plugin -T --full --mountable

Answer 4

我对差异的理解是引擎就像插件,并为现有应用程序添加功能.虽然可安装的应用程序本质上是一个应用程序,可以独立使用.

因此,如果您希望能够单独运行它或在其他应用程序中运行它,您将创建一个可安装的应用程序.如果您打算将它添加到现有应用程序中,但不能单独运行,那么您可以将其作为引擎.