ruby on rails - Where is undefined method called? -

i have decisions resource, nested under groups resource. has_many , belongs_to have been defined in models.

resources :groups   resources :decisions end 

...and have edit form @ path:

/groups/:group_id/decisions/:id/edit(.:format)

i'm getting error in rspec test:

failure/error: put :update, {:id => decision.to_param, :decision => valid_attributes, group_id: decision.group.id}, valid_session nomethoderror: undefined method `decision_url' #decisionscontroller:0x007ffeb23482e0>

and when navigate form in development environment, similar error:

<%= link_to 'edit', edit_group_decision_path(@group, @decision) %> 

nomethoderror @ /groups/6/decisions/5/edit

undefined method `decision_path' #<#:0x007fd1ff569130>

i'm using 'better_errors' gem, , cites first line of form_for no method error:

<%= form_for(@decision) |f| %> 

i don't have 'decision_url' anywhere in code. missing? shouldn't form_for know put update? there's valid path at:

/groups/:group_id/decisions/:id(.:format)

here part of log looks exciting:

rendered decisions/_form.html.erb (6.5ms)   rendered decisions/edit.html.erb within layouts/application (7.1ms) completed 500 internal server error in 9ms (activerecord: 0.1ms)  nomethoderror - undefined method `decision_path' #<#<class:0x007fd5d98527b0>:0x007fd5d400d618>:   actionpack (4.2.3) lib/action_dispatch/routing/polymorphic_routes.rb:220:in `polymorphic_method'   actionpack (4.2.3) lib/action_dispatch/routing/polymorphic_routes.rb:134:in `polymorphic_path'   actionview (4.2.3) lib/action_view/helpers/form_helper.rb:466:in `apply_form_for_options!'   actionview (4.2.3) lib/action_view/helpers/form_helper.rb:434:in `form_for' 

you've specified nested resources this:

resource groups   resource decisions end 

the routing, however, should specified using symbols, this:

resource :groups   resource :decisions end 

make sure models have proper relationships defined:

class group < activerecord::base   has_many :decisions end  class decision < activerecord::base   belongs_to :group end