Rails - How to make a conditional Radio Button checked?

Question

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

Pewter

Answer 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) %>

Atomicity

Neglects to account for the case of @permission.role_id == 2 as requested in the original question. Also, why not just use :checked => [email protected]_id.nil? sans ternary? Much more Ruby-esque. – Tercet

Just tried it but no luck. Also had to update it to solve for the two use cases above... Ideas? <%= radio_button_tag 'permission[role_id]', '2', { :checked => ( (@permission.role_id.nil? || (@permission.role_id == 2) ? true : false) } %> – Pewter

Strange, even doing { :checked => ( @permission.role_id == 2 ? false : false ) } is always checked true – Pewter

@Tercet Thanks for the feedback - I'm using the double-bang now. – Atomicity

@Pewter - I've edited the answer - the problem was that checked isn't passed in the options hash, it's just a standard parameter. – Atomicity

Answer 2

If you are using rails 7, the answer given by @skilldrick doesn't work. You have to use a hash instead of a just parameter.

...
form.radio_button :example_field, :example_value, checked:(example_value == "Example Value")

Marylynnmarylynne