passing id parameter from show action to new action via link_to, rails

I have some show action that displays one category. But from there I want via link to create new product. Point is that I passed category id and name via link_to.

It goes well, it opens Product/new action. And in browsing bar there is link like this http://mysite/products/new?id=43&name=Skeleji .its okay.

But how can I make those id and name available in form, where I am filling information about new product? After this when I click create, I want that theese values such category_id saves in db along with other information abaut product.

Between, Product and Category I have built relationship.

So far my code looks like this .

My Category/show action code looks like this.

<%= link_to "Add Product", {:controller => "products", :action => "new", :id => @category.id, :name => @category.name }%>

Product controller, new action looks like this.

def new
@product = Product.new
@product.category_id = @category.id
end

Clicking create it creates project, but without category_id. Where could be the problem ? Maybe the code what is under new action,actually should be under create action. About year ago I managed to do such thing, but I can't find that project.:(

Solution

You should be able to just set the values in your new action:

def new
  @product = Product.new
  @product.category_id = params[:id]
  @product.name = params[:name]
end

Then they will appear as such in your form.

But I don't think it's a good idea to call your parameter id because it's a default parameter name for resourceful routing. params[:id] in the ProductsController should typically always refer to a Product object. As it happens, you're using it in the new action which in normal use will never receive an id parameter so I doubt you'll get in any trouble, but it isn't very semantic.

If you let Product accept nested attributes for Category then I think you'd be able to simply do:

@product = Product.new(params[:product])

if you structured your params like: :product => { :name => "whatever", :category_attributes => { :id => 1 } } but that might be overkill depending on your needs.