Question

I have been debugging this the entire day.
I have two models in my application: teaClass & tea. In teaclass.rb, I have

has_many :teas

In tea.rb, I have ‘belongs_to :teaclass`.

I try to make the url looks like this "..teaclasses/:id/teas/:id"; so in teas_controller.rb, I put before_filter :get_teaClass

def show
@tea = @teaclass.teas.find(params[:id])

respond_to do |format|
  format.html # show.html.erb
  format.xml  { render :xml => @tea }
end
end

def new
if @teaclass.teas
    @tea = @teaclass.teas.new
    @teaclass.teas << @tea 
    #@tea = Tea.new
    else
        flash[:notice=>"failed"]
        @tea = Tea.new 
        @teaclass.teas << @tea 
    end
respond_to do |format|
  format.html # new.html.erb
  format.xml  { render :xml => @tea }
end
end

def get_teaClass
    begin
        @teaclass = Teaclass.find(params[:teaclass_id])rescue
        redirect_to teaclass_path, :notice => "Teaclass Required!"
    end
 end

But I keep getting an error saying “unknown attribute: teaclass_id”

/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/base.rb:2906:inassign_attributes'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/base.rb:2902:in `each'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/base.rb:2902:in `assign_attributes'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/base.rb:2474:in `initialize'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_collection.rb:380:in `new'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_collection.rb:380:in `send'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_collection.rb:380:in `method_missing'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/base.rb:2178:in `with_scope'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_proxy.rb:207:in `send'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_proxy.rb:207:in `with_scope'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_collection.rb:376:in `method_missing'
/home/jianpchen/repo/Teashop/app/controllers/teas_controller.rb:31:in `new'

Can anyone help me on this? Thank you.

Answer 1

I try to make the url looks like this “..teaclasses/:id/teas/:id”; so in teas_controller.rb, I put before_filter :get_teaClass

This only matters if you are trying to get nested routes setup but id doesn’t sound like you are doing that.

What you need to do is actually add the foreign id to the database. So check schema.rb and make sure that column exists.

Here is what you need to do.

1. Make sure you actually have the foreign in the database table tea.
2. If you do skip to the next step where I will show you a better way to write your code.
3. If you do not have ‘tea_class_id’ as an integer value on your ‘tea’ table you need to add it.
4. script/generate migration add_tea_class_id_to_tea
5. rake db:migrate
6. Now This is how your code should be written

routes.rb

map.resources :teas
map.resources :teas_classes

Models

models/tea.rb

class Tea < ActiveRecord::Base
    belongs_to :tea_class
end 

tea_class.rb

class TeaClass < ActiveRecord::Base
    has_many :teas
end 

controllers

teas_controller.rb

def new
   @tea = Tea.new
end

def show
  @tea = tea.find(params[:id)
end

def create
    @tea = Tea.new(params[:tea])
    if @tea.save
        redirect_to teas_path
    else
        render :action => 'new'
    end
end 

views

This is really important. Make sure you are passing the :tea_class_id as a parameter when you create a tea otherwise it doesn’t know how to make the association. It’s kinda behind the stage because you send params[:tea] but it is in those parameters where the tea_class_id is actually sent.

So… in your view you need to have some sort of way for users to choose a category or as you have it tea class and that is usually done with a select box when it is a one to many association.

new.html.erb

<% form_for(@tea) do |t| %>
    <%= t.collection_select :tea_class_id TeaClass.all, :id, :name %>
<% end %>

Make sure you have tea classes to actually fill the collection_select method. Google that plus rails api if you don’t get what’s going on.

Nested Routes (on the side)

Looked like you were trying to get the routes like teaclasses/:id/teas/:id. This is called nested routing and you will want to set that up in your routes.rb

map.resources :tea_classes_ do |tea_classes|
   tea_classes :teas
end
map.resources :teas

Then you can link to teas_classes/pour/teas/chinese. You should know this command rake routes. It will help you understand how the paths work.

But if you just want the link to get going it should be like this:

<%= link_to "Teas", tea_classes_teas_path(@tea_class)%>

You need to supply @teas do the link because it takes the id from that and when you click it gives it to the teas_controller' asparams[:teas_class_id]`. You don’t need to do anything without. It will automatically be in the url.