How to use Many to Many in Rails?

Question

Hello! In my project, I have users and quests. One User can join multiple quests and one quest can have multiple users. So I created a table called questing, containing the user_id and the quest_id. In my user.rb I did following:

require 'digest/sha1'
class User < ActiveRecord::Base
  has_many :questings
  has_many :quests ,:through =>:questings
  ...

My Quest.rb:

class Quest < ActiveRecord::Base
  has_many :questings
  has_many :users ,:through =>:questings
  ...

My Questing.rb:

class Questing < ActiveRecord::Base
  belongs_to :quest
  belongs_to :user
end

Now I want to create a link or button on my /quests/show.html.erb, calling an action in my controller, which will create the relationship between user and quest.

So, in my quest_controller I did:

  def join_quest
    @quest = Quest.find(params[:id])
    puts '************************'
    puts 'join quest:' + @quest.id
    puts '************************'
    respond_to do |format|
      format.html { redirect_to(@quest) }
      format.xml  { head :ok }
    end
  end

and in my show.html.erb I did:

<%= link_to 'join this quest!!!', :action => :join_quest %>

Now, clicking on this link will cause an error like: Couldn't find Quest with ID=join_quest and the url points to */quests/join_quest* instead of */quests/1/join_quest*

Now my questions:

Is my quests_controller the right place for my join_quest action, or should I move it to my users_controller?

Why do I get this error? How to solve it?

What do I have to write in my join_quest action for saving the relationship?

On my /users/show.html.erb I want to output all quests the user joined. How to do this? I have to get all this quests from my relationship table, right? How?

I hope you can help me! THX!

EDIT: When adding :member=>{:join_quest=>:get} to my routes.rb (map.resources :quests, :member=>{:join_quest=>:get}) it will call /quests/1/join_quest and call my action the right way. But I still can't figure out what to write in my action for saving the connection.

Answer 1

I'm assuming that you know the current user when your in the Quests controller. If so, then all you need to do is this.

@quest.users << current_user

Answer 2

To save the relationship you'll need something like

# quests controller
@quest.questings.create(:user_id => current_user)

But I'm assuming you can get the current_user.

Hope it helps...

Edit

Answering your questions:

Is my quests_controller the right place for my join_quest action, or should I move it to my users_controller?

You can do this in both users and quests controller, wherever it works better for you.

What do I have to write in my join_quest action for saving the relationship?

Answered above.

On my /users/show.html.erb I want to output all quests the user joined. How to do this? I have to get all this quests from my relationship table, right? How?

# users controller, show method
@user = User.find(params[:id], :include => :quests)

# show view
<% @user.quests.each do |quest| %>
   # print whatever you want from the quest
   <%= quest.any_attribute %>
<% end %>