Rails 3, nested multi-level forms and has_many through - ruby-on-rails

Question

I'm trying to get it to work but it dosen't!
I have
class User < ActiveRecord::Base
has_many :events, :through => :event_users
has_many :event_users
accepts_nested_attributes_for :event_users
end
class Event < ActiveRecord::Base
has_many :event_users
has_many :users, :through => :event_users
accepts_nested_attributes_for :users
end
class EventUser < ActiveRecord::Base
set_table_name :events_users
belongs_to :event
belongs_to :user
accepts_nested_attributes_for :events
accepts_nested_attributes_for :users
end
And also the table-layout
event_users
user_id
event_id
user_type
events
id
name
users
id
name
And this is my form
<%= semantic_form_for #event do |f| %>
<%= f.semantic_fields_for :users, f.object.users do |f1| %>
<%= f1.text_field :name, "Name" %>
<%= f1.semantic_fields_for :event_users do |f2| %>
<%= f2.hidden_field :user_type, :value => 'participating' %>
<% end %>
<% end %>
<%= link_to_add_association 'add task', f, :users %>
<% end %>
The problem is that if I create a new user this way, it doesn't set the value of user_type (but it creates a user and a event_users with user_id and event_id). If I go back to the edit-form after the creation of a user and submit, then the value of user_type is set in events_users. (I have also tried without formtastic)
Any suggestions? Thanks!
----edit----
I have also tried to have the event_users before users
<%= semantic_form_for #event do |f| %>
<%= f.semantic_fields_for :event_users do |f1| %>
<%= f1.hidden_field :user_type, :value => 'participating' %>
<%= f1.semantic_fields_for :users do |f2| %>
<%= f2.text_field :name, "Name" %>
<% end %>
<% end %>
<%= link_to_add_association 'add task', f, :event_users %>
<% end %>
but then it only throws me an error:
User(#2366531740) expected, got
ActiveSupport::HashWithIndifferentAccess(#2164210940)
--edit--
the link_to_association is a formtastic-cocoon method (https://github.com/nathanvda/formtastic-cocoon) but I have tried to do other approaches but with the same result
---edit----
def create
#event = Event.new(params[:event])
respond_to do |format|
if #event.save
format.html { redirect_to(#event, :notice => 'Event was successfully created.') }
format.xml { render :xml => #event, :status => :created, :location => #event }
else
format.html { render :action => "new" }
format.xml { render :xml => #event.errors, :status => :unprocessable_entity }
end
end
end

Answer 1

To be honest, i have never tried to edit or create a has_many :through in that way.
It took a little while, and had to fix the js inside formtastic_cocoon to get it working, so here is a working solution.
You need to specift the EventUser model, and then fill the User model (the other way round will never work).
So inside the models you write:
class Event < ActiveRecord::Base
has_many :event_users
has_many :users, :through => :event_users
accepts_nested_attributes_for :users, :reject_if => proc {|attributes| attributes[:name].blank? }, :allow_destroy => true
accepts_nested_attributes_for :event_users, :reject_if => proc {|attributes| attributes[:user_attributes][:name].blank? }, :allow_destroy => true
end
class EventUser < ActiveRecord::Base
belongs_to :user
belongs_to :event
accepts_nested_attributes_for :user
end
class User < ActiveRecord::Base
has_many :events, :through => :event_users
has_many :event_users
end
Then the views. Start with the events/_form.html.haml
= semantic_form_for #event do |f|
- f.inputs do
= f.input :name
%h3 Users (with user-type)
#users_with_usertype
= f.semantic_fields_for :event_users do |event_user|
= render 'event_user_fields', :f => event_user
.links
= link_to_add_association 'add user with usertype', f, :event_users
.actions
= f.submit 'Save'
(i ignore errors for now)
Then, you will need to specify the partial _event_user_fields.html.haml partial (here comes a little bit of magic) :
.nested-fields
= f.inputs do
= f.input :user_type, :as => :hidden, :value => 'participating'
- if f.object.new_record?
- f.object.build_user
= f.fields_for(:user, f.object.user, :child_index => "new_user") do |builder|
= render("user_fields", :f => builder, :dynamic => true)
and to end the _user_fields partial (which does not really have to be a partial)
.nested-fields
= f.inputs do
= f.input :name
This should work.
Do note that i had to update the formtastic_cocoon gem, so you will need to update to version 0.0.2.
Now it would be easily possible to select the user_type from a simple dropdown, instead of a hidden field, e.g. use
= f.input :user_type, :as => :select, :collection => ["Participator", "Organizer", "Sponsor"]
Some thoughts (now i proved it works):
this will always create new users on the fly, actually eliminating the need for the EventUser. Will you allow selecting existing users from a dropdown too?
personally i would turn it around: let users assign themselves to an event!

Answer 2

Does the events_users model not have an ID column? Since there's an additional field (user_type) then EventUser is a model and should probably have an ID. Maybe that's why user_type isn't being set in your first case.