Ruby-on-rails Rails：关于产量
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/7848020/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Rails: about yield
提问by Mellon
I saw some code in a Rails v2.3app.
我在Rails v2.3应用程序中看到了一些代码。
In layout/car_general.html.erb(this view is called by a method in cars_controller) , I saw the code:
在layout/car_general.html.erb（这个视图被cars_controller中的一个方法调用）中，看到了代码：
<body>
<%= yield %>
<%= javascript_include_tag 'jquery-1.4.2.min' %>
<% javascript_tag do %>
<%= yield :jstemplates %>
var some_car = new Object;
<%= yield :some_car %>
<% end -%>
</body>
Two questions to ask:
问两个问题：
- Where can I find the yield content of the first <%=yield%> under
<body>. - Is it a rails specific way to include js code in a view by using
<%= yield :jstemplates %>and what about<%= yield :some_car %>, is it point to a view or just to show the value ofsome_car?
- 在哪里可以找到第一个 <%=yield%> 下的产量含量
<body>。 - 它是通过使用将 js 代码包含在视图中的特定于 rails 的方式
<%= yield :jstemplates %>吗<%= yield :some_car %>，它是指向视图还是仅显示 的值some_car？
回答by Peter Brown
Without any arguments, yield will render the template of the current controller/action. So if you're on the cars/showpage, it will render views/cars/show.html.erb.
没有任何参数，yield 将呈现当前控制器/动作的模板。因此，如果您在cars/show页面上，它将呈现views/cars/show.html.erb.
When you pass yield an argument, it lets you define content in your templates that you want to be rendered outside of that template. For example, if your cars/showpage has a specific html snippet that you want to render in the footer, you could add the following to your show template and the car_generallayout:
当您传递 yield 参数时，它允许您在模板中定义要在该模板之外呈现的内容。例如，如果您的cars/show页面具有要在页脚中呈现的特定 html 片段，您可以将以下内容添加到您的展示模板和car_general布局中：
show.html.erb:
show.html.erb：
<% content_for :footer do %>
This content will show up in the footer section
<% end %>
layouts/car_general.html.erb
布局/car_general.html.erb
<%= yield :footer %>
The Rails Guide has a good section on using yield and content_for: http://guides.rubyonrails.org/layouts_and_rendering.html#understanding-yield
Rails 指南有一个关于使用 yield 和 content_for 的很好的部分：http: //guides.rubyonrails.org/layouts_and_rendering.html#understanding-yield
The API documentation for content_foris helpful too and has some other examples to follow. Note that it's for Rails 3.1.1 , but this functionality has not changed much since 2.3, if at all and should still apply for 3.0.x and 3.1.x.
的 API 文档content_for也很有帮助，还有一些其他示例可供参考。请注意，它适用于 Rails 3.1.1 ，但此功能自 2.3 以来没有太大变化，如果有的话，仍然适用于 3.0.x 和 3.1.x。
