Rails表单（选择/选项） - 如何使用HAML标记所选选项？

What's the quickest and most elegant way to mark currently selected option value in the form in HAML?

在HAML中以表格形式标记当前所选期权值的最快捷，最优雅的方法是什么？

%form{:action => '', :method => 'get'}
   %select{:name => 'param_name'}
      %option{:value => 'A'} A data
      %option{:value => 'B'} B data

One way:

单程：

- if params[:param_name] == "A"
  %option{:value => 'A', :selected => 'selected'} A data
- else
  %option{:value => 'A'} A data

but this is inappropriate when the select box will has many option fields...

但是当选择框有很多选项字段时，这是不合适的...

2 个解决方案

#1

Something like this will work (using the older "hashrocket syntax" with the operator =>)

像这样的东西将起作用（使用较旧的“hashrocket语法”与operator =>）

%select
  %option{:value => "a", :selected => params[:x] == "a"}= "a"
  %option{:value => "b", :selected => params[:x] == "b"}= "b"

Or, in newer Ruby versions (1.9 and greater):

或者，在较新的Ruby版本（1.9及更高版本）中：

%select
  %option{value: "a", selected: params[:x] == "a"}= "a"
  %option{value: "b", selected: params[:x] == "b"}= "b"

#2

You should unleash the power of rails helpers.

你应该释放铁路助手的力量。

For select tag:

对于选择标签：

= select_tag :param_name, options_for_select([['A data', 'A'], ['B data', 'B']], params[:param_name])

Also, instead of raw %form use form_tag or better form_for when it's possible (or more better simple_form or formtastic)

另外，在可能的情况下使用form_tag或更好的form_for而不是raw％form（或者更好的simple_form或formtastic）