_form.html.erb

<%= form_for(@event) do |f| %>
  <% if @event.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@event.errors.count, "error") %> prohibited this event from being saved:</h2>

      <ul>
      <% @event.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :title %><br />
    <%= f.text_field :title %>
  </div>
  <div class="field">
    <%= f.label :starts_at %><br />
    <%= f.datetime_select :starts_at %>
  </div>
  <div class="field">
    <%= f.label :ends_at %><br />
    <%= f.datetime_select :ends_at %>
  </div>
  <div class="field">
    <%= f.label :all_day %><br />
    <%= f.check_box :all_day %>
  </div>
  <div class="field">
    <%= f.label :description %><br />
    <%= f.text_field :description %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

event.rb

class Event
  include Mongoid::Document
  include Mongoid::Timestamps

  field :title, :type => String
  field :starts_at, :type => DateTime
  field :ends_at, :type => DateTime
  field :all_day, :type => Boolean
  field :description, :type => String

  #scope :before2, lambda {|end_time| {:conditions => ["ends_at < ?", Event.format_date(end_time)] }}
  #scope :after2, lambda {|start_time| {:conditions => ["starts_at > ?", Event.format_date(start_time)] }}

  scope :before, lambda {|end_time| where(:ends_at.lt => Event.format_date(end_time))}
  scope :after, lambda {|start_time| where(:ends_at.gt => Event.format_date(start_time))}

  # need to override the json view to return what full_calendar is expecting.
  # http://arshaw.com/fullcalendar/docs/event_data/Event_Object/
  def as_json(options = {})
    {
      :id => self.id,
      :title => self.title,
      :description => self.description || "",
      :start => starts_at.rfc822,
      :end => ends_at.rfc822,
      :allDay => self.all_day,
      :recurring => false,
      :url => Rails.application.routes.url_helpers.event_path(id)
    }

  end

  def self.format_date(date_time)
    Time.at(date_time.to_i).to_formatted_s(:db)
  end

end

events_controller.rb

class EventsController < ApplicationController
  # GET /events
  # GET /events.xml
  def index   
    # full_calendar will hit the index method with query parameters
    # 'start' and 'end' in order to filter the results for the
    # appropriate month/week/day.  It should be possiblt to change
    # this to be starts_at and ends_at to match rails conventions.
    # I'll eventually do that to make the demo a little cleaner.
    @events = Event.scoped  
    @events = @events.after(params['start']) if (params['start'])
    @events = @events.before(params['end']) if (params['end'])
    
    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @events }
      format.js  { render :json => @events }
    end
  end

  # GET /events/1
  # GET /events/1.xml
  def show
    @event = Event.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.xml  { render :xml => @event }
      format.js { render :json => @event.to_json }
    end
  end

  # GET /events/new
  # GET /events/new.xml
  def new
    @event = Event.new

    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @event }
    end
  end

  # GET /events/1/edit
  def edit
    @event = Event.find(params[:id])
  end

  # POST /events
  # POST /events.xml
  def create
    @event = Event.new(params[:event])

    respond_to do |format|
      if @event.save
        format.html { redirect_to(@event, :notice => "Event was successfully created. #{params[:event].to_s}") }
        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

  # PUT /events/1
  # PUT /events/1.xml
  # PUT /events/1.js
  # when we drag an event on the calendar (from day to day on the month view, or stretching
  # it on the week or day view), this method will be called to update the values.
  # viv la REST!
  def update
    @event = Event.find(params[:id])
    
    respond_to do |format|
      if @event.update_attributes(params[:event])
        format.html { redirect_to(@event, :notice => 'Event was successfully updated.') }
        format.xml  { head :ok }
        format.js { head :ok}
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @event.errors, :status => :unprocessable_entity }
        format.js  { render :js => @event.errors, :status => :unprocessable_entity }
      end
    end
  end

  # DELETE /events/1
  # DELETE /events/1.xml
  def destroy
    @event = Event.find(params[:id])
    @event.destroy

    respond_to do |format|
      format.html { redirect_to(events_url) }
      format.xml  { head :ok }
    end
  end
end