Rails:关于产量 [英] Rails: about yield
问题描述
我在 Rails v2.3 应用中看到了一些代码.
I saw some code in a Rails v2.3 app.
在layout/car_general.html.erb(这个view被cars_controller中的一个方法调用)，看到了代码:
In layout/car_general.html.erb (this view is called by a method in cars_controller) , I saw the code:
<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>
要问的两个问题:
- 在哪里可以找到
下第一个<%=yield%>的yield含量. - 是否是通过使用在视图中包含 js 代码的特定于 Rails 的方式
<%= yield :jstemplates %>那么<%= yield :some_car %>是指向视图还是仅仅显示值some_car?
- 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?
推荐答案
不带任何参数，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.
Without any arguments, yield will render the template of the current controller/action. So if you're on the cars/show page, it will render views/cars/show.html.erb.
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 页面有一个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:
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/show page 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_general layout:
show.html.erb:
<% content_for :footer do %>
This content will show up in the footer section
<% end %>
layouts/car_general.html.erb
<%= yield :footer %>
Rails 指南中有一个很好的部分介绍了使用 yield 和 content_for:http://guides.rubyonrails.org/layouts_and_rendering.html#understanding-yield
The Rails Guide has a good section on using yield and content_for: http://guides.rubyonrails.org/layouts_and_rendering.html#understanding-yield
content_for 也很有帮助，并且还有其他一些示例可供参考.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.
The API documentation for content_for is 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.
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