Rails - How to make a conditional Radio Button checked?

问题

Given a radio button like so:

<%= radio_button_tag 'permission[role_id]', '2' %>

How can I make the radio buttons checked status condition. To only be checked if @permission.role_id.nil? or if @permission.role_id == 2?

I tried:

<%= radio_button_tag 'permission[role_id]', '2', @permission.role_id.nil? ? {:checked => true} : {:checked => false} %>

Thanks

回答1:

The documentation for radio_button_tag says that checked isn't an options hash parameter, it's just a normal one:

radio_button_tag(name, value, checked = false, options = {})

So, you need to do this:

<%= radio_button_tag 'permission[role_id]', '2', !!(@permission.role_id.nil? || @permission.role_id == 2) %>

来源：https://stackoverflow.com/questions/4708910/rails-how-to-make-a-conditional-radio-button-checked