Question

I have a Rails app, with 2 models : a User model and a Micropost model, from the RoR tutorial.
I implemented the whole Twitter app, to get started with a Rails.

Now I wanted to use the code I have to create a ride share application : people posting rides that they are going to make (when they drive), apply to a ride when they want to be a passenger, following users to get their rides on their feed (instead of just posts) and being followed by other users. We see that a “user” actually plays 2 roles : driver and passenger. I’m good with the driver : it’s just the author of the post, no change to make.
But not passenger…

What I want : have a “Hop in” button on each ride post — user clicks, the button turns to “Jump off” and we have a record that gets created in the db, in the PassengerRide table (ride_id, passenger_id) // when we click on “Jump off” the button turns to “Hop in” and the record that had been saved gets deleted from the PassengerRide table.

What I did : I tried to mimic the implementation of the following and adapt to what I want

1) generated the PassengerRide table (many to many relation between a User and a Micropost)
with

    rails generate model PassengerRide ride_id:integer passenger_id:integer

2) in passenger_ride.rb :

    attr_accessible :ride_id 

EDIT: I removed this hoping it’d fix the problem and it didn’t solve the problem.

3)established the associations! (remember: I only have a User table and a Micropost table)

in user.rb

    has_many :passenger_rides, foreign_key: "passenger_id", dependent: :destroy
    has_many :rides, through: :passenger_rides, class_name: "Micropost"

in passenger_ride.rb

    belongs_to :passenger, class_name: "User"
    belongs_to :ride, class_name: "Micropost"

in micropost.rb

    has_many :passenger_rides, foreign_key: "ride_id", dependent: :destroy
    has_many :passengers, through: :passenger_rides, source: :passenger, class_name: "User"

4) methods in the user model to create the passenger_ride records

    def hopped_in?(ride)
        self.passenger_rides.find_by_ride_id(ride.id)
    end

    def hop_in!(ride)
       self.passenger_rides.create!(ride_id: ride.id)
    end

    def jump_off!(ride)
     self.passenger_rides.find_by_ride_id(ride.id).destroy
    end

5) add rides to the user controller

in routes.rb

   resource :users do
       member do
          get :rides
       end
   end

6) views :
in app/views/microposts/_hopin.html.erb

    <%= form_for(current_user.rides.build(ride_id: @micropost.id)) do |f| %>
        <div><%= f.hidden_field :ride_id %></div>
        <%= f.submit "Hop in", :class => "btn btn-large btn-primary" %>
    <% end %>

in app/views/microposts/_jumpoff.html.erb

    <%= form_for(current_user.rides.find_by_ride_id(@micropost),
         html: { method: :delete }) do |f| %>
    <%= f.submit "Jump off", :class => "btn btn-large" %>
    <% end %>

in app/views/microposts/_ride_form.html.erb

      <div id="ride_form">
         <% if current_user.hopped_in?(@micropost) %>
              <%= render 'microposts/jumpoff' %>
         <% else %>
              <%= render 'microposts/hopin' %>
         <% end %>
      </div>

The local server rendered the following :

   Started GET "/" for 127.0.0.1 at 2012-03-30 21:39:06 -0400
   Processing by PagesController#home as HTML
    ←[1m←[36mUser Load (0.0ms)←[0m  ←[1mSELECT "users".* FROM "users" WHERE "users
   "."remember_token" = 'R8o1mYu49bhrsrIyIPO-ow' LIMIT 1←[0m
     ←[1m←[35m (0.0ms)←[0m  SELECT DISTINCT "users".id FROM "users" INNER JOIN "rel
   ationships" ON "users"."id" = "relationships"."followed_id" WHERE "relationships
   "."follower_id" = 3
     ←[1m←[36m (1.0ms)←[0m  ←[1mSELECT COUNT(*) FROM "microposts" WHERE "microposts
   "."user_id" = 3←[0m
     Rendered shared/_user_info.html.erb (4.0ms)
     ←[1m←[35m (0.0ms)←[0m  SELECT COUNT(*) FROM "users" INNER JOIN "relationships"
    ON "users"."id" = "relationships"."followed_id" WHERE "relationships"."follower
   _id" = 3
     ←[1m←[36m (0.0ms)←[0m  ←[1mSELECT COUNT(*) FROM "users" INNER JOIN "relationsh
   ips" ON "users"."id" = "relationships"."follower_id" WHERE "relationships"."foll
   owed_id" = 3←[0m
     ←[1m←[35m (0.0ms)←[0m  SELECT COUNT(*) FROM "microposts" INNER JOIN "passenger
   _rides" ON "microposts"."id" = "passenger_rides"."ride_id" WHERE "passenger_ride
   s"."passenger_id" = 3
     Rendered shared/_stats.html.erb (15.0ms)
     ←[1m←[36m (0.0ms)←[0m  ←[1mSELECT COUNT(*) FROM "microposts" WHERE (user_id IN
    (1) OR user_id = 3)←[0m
     ←[1m←[35mMicropost Load (0.0ms)←[0m  SELECT "microposts".* FROM "microposts" W
   HERE (user_id IN (1) OR user_id = 3) ORDER BY microposts.created_at DESC LIMIT 3
   0 OFFSET 0
     ←[1m←[36mUser Load (0.0ms)←[0m  ←[1mSELECT "users".* FROM "users" WHERE "users
   "."id" = 3 LIMIT 1←[0m
     ←[1m←[35mPassengerRide Load (0.0ms)←[0m  SELECT "passenger_rides".* FROM "pass
   enger_rides" WHERE "passenger_rides"."passenger_id" = 3 AND "passenger_rides"."r
   ide_id" IS NULL LIMIT 1
   WARNING: Can't mass-assign protected attributes: ride_id
     Rendered microposts/_hopin.html.erb (4.0ms)
     Rendered microposts/_ride_form.html.erb (9.0ms)
     Rendered shared/_feed_item.html.erb (15.0ms)
     Rendered shared/_feed.html.erb (20.0ms)
     Rendered pages/home.html.erb within layouts/application (46.0ms)
   Completed 500 Internal Server Error in 155ms


   ActionView::Template::Error (undefined method `ride_id' for #<Micropost:0x5f53a1

   0>):
       1: <%= form_for(current_user.rides.build(ride_id: @micropost.id)) do |f| %>
       2:   <div><%= f.hidden_field :ride_id %></div>
       3:   <%= f.submit "Hop in", :class => "btn btn-large btn-primary" %>
       4: <% end %>
   app/views/microposts/_hopin.html.erb:2:in `block in _app_views_microposts__hop
   in_html_erb___661389729_52209444'
     app/views/microposts/_hopin.html.erb:1:in `_app_views_microposts__hopin_html_e
   rb___661389729_52209444'
     app/views/microposts/_ride_form.html.erb:6:in `_app_views_microposts__ride_for
   m_html_erb___54007412_52167144'
     app/views/shared/_feed_item.html.erb:12:in `_app_views_shared__feed_item_html_
   erb___851424678_48417588'
     app/views/shared/_feed.html.erb:3:in `_app_views_shared__feed_html_erb___10631
   41135_48687708'
   app/views/pages/home.html.erb:19:in `_app_views_pages_home_html_erb__74940785_
   48176280'

Thank you so much for taking time to read that, I couldn’t be more thorough !

Answer 1

Shouldn’t it be passenger_rides instead of rides in the _hopin.html.erb partial? I.e.:

<%= form_for(current_user.passenger_rides.build(ride_id: @micropost.id)) do |f| %>
    <div><%= f.hidden_field :ride_id %></div>
    <%= f.submit "Hop in", :class => "btn btn-large btn-primary" %>
<% end %>