How to have a collasped drop down list in rails simple_form

问题

In my app, there are two models: rfq and standard. Their relationship is many-to-many. In rfq creating screen, the code below displays a list of available for selection in drop down list:

<%= simple_form_for @rfq do |f| %>    
<%= f.association :standards, :collection => Standard.active_std.all(:order => 'name'), :label_method => :name, :value_method => :id %> 
<% end %>

The problem is that the list is not collapsed, which means there are multiple standards displayed in a multi-line boxes. How can I reduce the box to one line only?

Thanks.

UPDATED: here is the screen shot of multiple line list box:

回答1:

It's creating a multi-select because one rfq can have many standards, so it allows you to ctrl-click to select many standards.

You could try adding :input_html => { :size =>'1' } but I'm not sure that will preserve the scrollbar. It definitely won't drop down.

Here's someone else who wanted to do the same thing: HTML muliple select should look like HTML select. One of the answers refers to a Dropdown Check List implemented in jQuery, but that would take some work to integrate with SimpleForm.

SimpleForm has a very helpful Google Group--you might get more ideas there:

http://groups.google.com/group/plataformatec-simpleform

回答2:

You can add as: :collection_select

回答3:

Use

=f.collecion_select, model_associated_ids, collection, value, label 

in your is like this

=f.collection_select, :standard_ids, Standard.active_std.all, :id, :name

you can find more info here

https://github.com/plataformatec/simple_form

来源：https://stackoverflow.com/questions/8795268/how-to-have-a-collasped-drop-down-list-in-rails-simple-form