Rails HATM (Has and belongs to many)

Nested forms with HABTM and HasManyThrough

Start with the models

has_many :events # creates ……
accepts_nested_attributes_for :events, :allow_destroy => true # creates….
attr_accessible :events_attributes # creates…

Then the Views

<%= simple_nested_form_for @person, :html => { :class => "form-horizontal" } do |f| %>

<% if !@person.new_record? %>

f.simple_fields_for creates a "form in a form" (event_form in this case)
 
 <h3>Events in <%= @person.fullname %>'s life </h3>

<%= f.simple_fields_for :events do |event_form| %>
 <%= event_form.input :name, :label_html => {:class => 'horiz_input'}, :input_html => {:class => 'horiz_input'}, :placeholder => 'Event name', :readonly => readonly %>
 <%= event_form.input :date, :label_html => {:class => 'horiz_input'}, :input_html => {:class => 'horiz_input'}, :placeholder => 'Event date', :readonly => readonly %>
 <%= event_form.input :comment, :label_html => {:class => 'horiz_input'}, :input_html => {:class => 'horiz_input'}, :placeholder => 'Event comment', :readonly => readonly %>
 <% end %>
 
 If you DONT use event_form and use accepts_nested_attributes_for you might end up with the _destroy attribute attached to Person instead of the "event_attributes"

nested_form adds this JS helper
 <% if !readonly %>
 <p><%= f.link_to_add "Add an event", :events %></p>
 <% end %>

THROUGH

Model Person:

has_many :clicks
has_many :users, :through => :clicks
accepts_nested_attributes_for :users, :allow_destroy => true
attr_accessible :users_attributes

Person.clicks.first.user_id
Person.clicks.first.count # How many times has this Person been clicked by this user….?