ERB Radio Button causing string error - html

Question

I'm working with forms using Embedded Ruby and Rails 4 to create and edit Users. Each User has to be assigned a Role on creation. Initially the form was using check boxes for this and was working fine. Upon changing over to radio buttons however, I get an error.
This is the form:
<%= simple_form_for(#user, html: {class: 'form-horizontal'}) do |f| %>
<%= f.error_notification %>
<div class="form-inputs">
<%= f.input :name, autofocus: true %>
<%= f.input :email %>
<%= f.input :phone_number %>
<%= f.input :institution_pid, collection: institutions_for_select, as: :select, label: "Institution" %>
<%= f.association :roles, collection: roles_for_select, as: :radio_buttons %>
<%= f.input :password %>
<%= f.input :password_confirmation %>
</div>
<br>
<div class="form-actions">
<%= button_tag(type: 'submit', class: "btn doc-action-btn btn-success") do %>
<i class="glyphicon glyphicon-check"></i> Submit
<% end %>
<%= link_to #user, {class: "btn doc-action-btn btn-cancel"} do %>
<i class="glyphicon glyphicon-remove"></i> Cancel
<% end %>
</div>
I'm specifically asking about the f.association bit. Before, when I was using
as: :check_boxes
it worked exactly as it was supposed to. Now I get this error message:
NoMethodError in UsersController#update
undefined method `reject' for "77":String
I should note that "77" is the value of one of the radio button options.
The method throwing the error is this:
def build_role_ids
[].tap do |role_ids|
roles = Role.find(params[:user][:role_ids].reject &:blank?)
roles.each do |role|
authorize!(:add_user, role)
role_ids << role.id
end
end
end
The HTML when using radio buttons looks like this:
<label class="radio">
<input class="radio_buttons optional" id="user_role_ids_77" name="user[role_ids]" type="radio" value="77">
"Institutional Admin"
</label>
When using check boxes:
<label class="checkbox">
<input class="check_boxes optional" id="user_role_ids_77" name="user[role_ids][]" type="checkbox" value="77">
"Institutional Admin"
</label>
If I'm missing something or you need more information, please let me know. Thank you!

Answer 1

With checkboxes, user can select multiple values so you got an Array of role_ids returned in params[:user][:role_ids]. reject method is implemented for Arrays. Hence, it worked in that case.
With radio buttons, only one value would be selected at a time, so you'll get a String value for role_ids in params[:user][:role_ids]. reject method is not implemented for Strings. Hence, the error.
Instead of
params[:user][:role_ids].reject &:blank?
you can check if role_ids is empty or not, as it is a String object.
params[:user][:role_ids].empty?
and update build_role_ids method keeping in mind that role_ids is a String object and not an Array.

Answer 2

This error seems to indicate that params[:user][:role_ids] is not an Array but a single String value. This would make sense since you are changing from checkboxes (multiple values can be selected at a time = Array) to radio buttons (only a single value can be selected at a time = String).
If you truly want to change from checkboxes to radio buttons, then you'll need to update your build_role_ids method logic to expect a single value instead of an array of values.