HABTM & CheckBoxes

I’m trying to achieve something that I assume is fairly common?

I have a Category table and a Brand Table.
When I create a new Category I want a list of checkboxes to appear,
and when checked they update the category_brand table.

Here are the models.
class Category < ActiveRecord::Base
has_and_belongs_to_many :brands
class Brand < ActiveRecord::Base
has_and_belongs_to_many :categories

Here is the view to add a new category.

Add a new Category

<% form_for(@category) do |f| %> <%= f.error_messages %>

<%= f.label :name %>
<%= f.text_field :name %>

Add Brands required for this new category

    <% for b in @brands do -%>
  • <%= check_box_tag "categories[brand_ids][]", "#{b.id}" -%> <%= "#{b.name}" -%>
  • <% end -%>

<%= f.submit "Create" %>

<% end %>


<%= link_to 'Back', categories_path %>

I have read all the documentation & tutorials I can find on this and
it is not clear to me if anything has to be done in the controller?
Some examples imply it happens because of the association and other
example have code such as:
@category.brands = brand.find(@params[:brand_ids]) if
Which produces an error for me…
You have a nil object when you didn’t expect it!

TIA - Dave P.

Davo wrote:

@category.brands = brand.find(@params[:brand_ids]) if @params[:categories][:brand_ids]

check this

Pokkai D. wrote:

Davo wrote:

@category.brands = brand.find(@params[:categories][:brand_ids]) if @params[:categories][:brand_ids]

check this

All working, no code required in controller
( other than code mentioned in RailsCasts HABTM
#17 HABTM Checkboxes - RailsCasts )

I had the naming wrong for the brands_categories table !

cheers, Dave

On Oct 13, 1:28 pm, Pokkai D. [email protected]