Controller help with :has_many relationship

rubyonrails-talk
1

Hey,

I’m having trouble understanding how to correctly build and save an object that has a has_many relationship. I am trying to map Products to Categories through CategoryAssignments:

Model:

class Product < ActiveRecord::Base has_many :category_assignments … end

class Category < ActiveRecord::Base has_many :category_assignments end

class CategoryAssignment < ActiveRecord::Base

belongs_to :category belongs_to :product end

I generated a scaffold for Products and in it I changed the view for “new” to add a select box of categories. The idea is that when you are creating a product, you can also pick what categories it belongs to.

<%= f.label :category_assignments %>
<%= collection_select(:category_assignment, :category_id, @categories, :id, :name, options ={:prompt => true}, html_options ={:multiple => true, :size => 6}) %>

My issue is in the controller. Specifically, for “create”, I am having trouble building the CategoryAssignments correctly. Here is what I have (it’s not working).

GET /products/new

GET /products/new.xml

def new @product = Product.new @categories = Category.find(:all)

respond_to do |format|
  format.html # new.html.erb
  format.xml  { render :xml => @product }

end

end

POST /products

POST /products.xml

def create @product = Product.new(params[:product]) logger.info(“New Product looks like #{params[:product]}\n”);

[logger.info](http://logger.info)("New Category Assignment looks like #{params[:category_assignment]}\n");

respond_to do |format|
  if @product.save #and @category_assignment.each { |category_assignment| category_assignment.save }

    @category_assignments = @product.category_assignments.build(params[:category_assignment])
    @category_assignments.save
    [logger.info](http://logger.info)("Category Assignment ARRAY == @category_assignments\n");


    flash[:notice] = 'Product was successfully created.'
    format.html { redirect_to(@product) }
    format.xml  { render :xml => @product, :status => :created, :location => @product }

  else
    format.html { render :action => "new" }
    format.xml  { render :xml => [@product.errors, @category_assignment.errors], :status => :unprocessable_entity }
  end
end

end

Can someone give me some advice on the correct way of building CategoryAssignments?

Thanks!