Rails 4 - checkboxes for has_and_belongs_to_many association

Question

I recently had a problem getting checkboxes to work for a has_and_belongs_to_many (HABTM) association in Rails 4. I was able to find the information on how to get it working

Answer 1

The form should have something like this:

<%= form_for(@kennel) do |form| %>
    ...
    

        
Handlers
        <%= hidden_field_tag("kennel[handler_ids][]", nil) %>
        <% Handler.order(:name).each do |handler| %>
            <%= check_box_tag("kennel[handler_ids][]", id, id.in?(@kennel.handlers.collect(&:id))) %> <%= handler.name %>
        <% end %>
    
    ...
<% end %>

The hidden_field_tag allows the user to uncheck all the boxes and successfully remove all the associations.

The controller needs to allow the parameter through strong parameters in the permitted_params method:

params.permit(kennel: [:city, :state
    {handler_ids: []},
    :description, ...
    ])

References:

• http://railscasts.com/episodes/17-habtm-checkboxes
• https://coderwall.com/p/_1oejq