How to link_to correct show page from feed? - ruby-on-rails

Question

If a user clicks on:
activities/valuations/_create.html.erb
<%= link_to valuation_path(activity) do %>
<%= activity.trackable.name %>
<% end %>
he is directed to, for example, the error:
Couldn't find Valuation with 'id'=24
because the valuation is actually 7. This is because this line of code is trying to find the valuation show page by looking at the id number as an activity instead of the id number as a valuation.
To fix it I tried:
<%= link_to valuation_path(#valuation) do %>
<%= activity.trackable.name %>
<% end %>
but that gives the error:
ActionController::UrlGenerationError in Activities#index
No route matches {:action=>"show", :controller=>"valuations",
:id=>nil} missing required keys: [:id]
How do we rewrite the code to take the user to the correct valuations show page?
activities_controller
class ActivitiesController < ApplicationController
def index
#activities = Activity.order("created_at desc").paginate(:page => params[:page])
end
def show
redirect_to(:back)
end
def like
#activity = Activity.find(params[:id])
#activity_like = current_user.activity_likes.build(activity: #activity)
if #activity_like.save
#activity.increment!(:likes)
flash[:success] = 'Thanks for liking!'
else
flash[:error] = 'Two many likes'
end
redirect_to(:back)
end
end
activity.rb
class Activity < ActiveRecord::Base
self.per_page = 20
has_many :notifications
belongs_to :user
belongs_to :trackable, polymorphic: true
def conceal
trackable.conceal
end
def page_number
(index / per_page.to_f).ceil
end
private
def index
Activity.order(created_at: :desc).index self
end
end
activities/index
<% #activities.each do |activity| %>
<%= link_to activity.user.name, activity.user %></b>
<%= render "activities/#{activity.trackable_type.underscore}/#{activity.action}", activity: activity %>
<% end %>

Answer 1

it seems like you want to do a nested resource,
when you have activities/valuations/_create.html.erb , that means you should have a nested route
#routes.rb
resources :activities do
resources :valuations
end
So your link should be something like
<%= link_to 'link', activities_valuataions_path(activity, #validation) %>
if you could post your routes
rake routes
it should be easy to track down the problem