NameError with a Many to Many association - ruby-on-rails

Question

I'm trying to add a Join/Unjoin button to user created Events, similar to a Follow/Unfollow button for Users.
I'm not sure what to define #rsvps as in the event#show
NameError in Events#show
undefined local variable or method `event' for #<#:0x007f9dfaf9d978>
show.html.erb
<%= link_to "Join Event", rsvps_path(:event_id => event), :method => :post %>
events_controller.rb
def show
#event = Event.find(params[:id])
#user = current_user
##rsvp = ???? something here ????
end
rsvps_controller.rb
class RsvpsController < ApplicationController
before_filter :signed_in_user
def create
#rsvp = current_user.rsvps.build(:event_id => params[:event_id])
if #rsvp.save
flash[:notice] = "Joined event."
redirect_to root_url
else
flash[:error] = "Unable to join event."
redirect_to root_url
end
end
def destroy
#rsvp = current_user.rsvps.find(params[:id])
#rsvp.destroy
flash[:notice] = "Unjoin Event."
redirect_to current_user
end
end
Here are the models
rsvp.rb
class Rsvp < ActiveRecord::Base
attr_accessible :event_id, :user_id
belongs_to :user
belongs_to :event
end
user.rb
has_many :rsvps
has_many :events, through: :rsvps, dependent: :destroy
event.rb
belongs_to :user
has_many :rsvps
has_many :users, through: :rsvps, dependent: :destroy

Answer 1

Your undefined local variable or method error seems to be coming from trying to pass :event_id => event to your controller through rsvp_path. Instead you should just be passing the event object like so
<%= link_to "Join Event", rsvps_path(event), :method => :post %>
the line #event = Event.find(params[:id]) in your controller will take care of figuring out what event you passed to it.

Answer 2

I think this code would be more rails-ish.
# user.rb
has_many :users_events
has_many :events, through: :users_events
# event.rb
has_many :users_events
has_many :users, through: :users_events
# users_event.rb
belongs_to :user
belongs_to :event
ActiveRecord do everything else. 8)
For example user.events and event.users methods.
Join and unjoin to user actions may be processed by events controller. Update method can look like this
# events_controller.rb
def update
respond_to do |format|
#event = Event.find(params[:id])
#event.users << current_user if params[:action] == 'join'
#event.users.delete(current_user) if params[:action] == 'unjoin'
if #event.update_attributes(params[:event])
format.html { redirect_to #event, notice: 'Event was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: "edit" }
format.json { render json: #event.errors, status: :unprocessable_entity }
end
end
end
A little bit messy, but I hope the idea is clear.