Polymorphic model, Forms and AssociationTypeMismatch

Hi All

i have two models, Content and Page

class Content < ActiveRecord::Base
attr_accessible :large_description, :short_description
belongs_to :contentable , :polymorphic => trueend
class Page < ActiveRecord::Base

extend FriendlyId
friendly_id :title, use: [:slugged, :history]

attr_accessible :active, :menu, :slug, :title, :contents

validates :title, presence: true

has_many :contents, as: :contentableend

this is my simple form to create a new page with contents

<%= form_for([:admin,@page], :html => {:class => “nice custom”}) do |f|
%>

<%= f.label :title, "Title"%> <%= f.text_field :title, :class => 'input-text'%>
<%= f.fields_for :contents do |content_form| %>
<%= content_form.label :short_description, "Short Description"%> <%= content_form.text_area :short_description, :class => 'tinymce expand'%>
<%= content_form.label :large_description, "Large Description"%> <%= content_form.text_area :large_description, :class => 'tinymce expand'%>
<% end %>
<%= f.submit "Create", :class => 'button small nice blue'%>
<% end %>

and finally this is my page controller

class Admin::PagesController < ApplicationController
layout ‘admin’

def index
@pages = Page.order(“created_at”)
end

def new
@page = Page.new
end

def create
@page = Page.new(params[:page])
if @page.save
redirect_to page_url
else
render :new
end
end

def show
@page = Page.find(params[:id])
end

def destroy
@page = Page.find(params[:id])
@page.destroy
redirect_to page_url
endend

i have used a namespace Admin.
so the problem is when i send the form, i receive this error and i don’t
undersand why have a mismatch:

ActiveRecord::AssociationTypeMismatch in Admin::PagesController#create
Content(#70150608194420) expected, got Array(#70150590276780)

activerecord (3.2.8)
lib/active_record/associations/association.rb:204:in
raise_on_type_mismatch' activerecord (3.2.8) lib/active_record/associations/collection_association.rb:308:inblock
in replace’
activerecord (3.2.8)
lib/active_record/associations/collection_association.rb:308:in each' activerecord (3.2.8) lib/active_record/associations/collection_association.rb:308:inreplace’
activerecord (3.2.8)
lib/active_record/associations/collection_association.rb:41:in writer' activerecord (3.2.8) lib/active_record/associations/builder/association.rb:51:inblock in
define_writers’
activerecord (3.2.8) lib/active_record/attribute_assignment.rb:94:in
block in assign_attributes' activerecord (3.2.8) lib/active_record/attribute_assignment.rb:93:ineach’
activerecord (3.2.8) lib/active_record/attribute_assignment.rb:93:in
assign_attributes' activerecord (3.2.8) lib/active_record/base.rb:498:ininitialize’
app/controllers/admin/pages_controller.rb:13:in new' app/controllers/admin/pages_controller.rb:13:increate’
actionpack (3.2.8) lib/action_controller/metal/implicit_render.rb:4:in
send_action' actionpack (3.2.8) lib/abstract_controller/base.rb:167:inprocess_action’
actionpack (3.2.8) lib/action_controller/metal/rendering.rb:10:in
process_action' actionpack (3.2.8) lib/abstract_controller/callbacks.rb:18:inblock in
process_action’
activesupport (3.2.8) lib/active_support/callbacks.rb:414:in
_run__3558390125630086563__process_action__2004224720818030891__callbacks' activesupport (3.2.8) lib/active_support/callbacks.rb:405:in__run_callback’
activesupport (3.2.8) lib/active_support/callbacks.rb:385:in
_run_process_action_callbacks' activesupport (3.2.8) lib/active_support/callbacks.rb:81:inrun_callbacks’
actionpack (3.2.8) lib/abstract_controller/callbacks.rb:17:in
process_action' actionpack (3.2.8) lib/action_controller/metal/rescue.rb:29:inprocess_action’
actionpack (3.2.8) lib/action_controller/metal/instrumentation.rb:30:in
block in process_action' activesupport (3.2.8) lib/active_support/notifications.rb:123:inblock
in instrument’
activesupport (3.2.8)
lib/active_support/notifications/instrumenter.rb:20:in instrument' activesupport (3.2.8) lib/active_support/notifications.rb:123:ininstrument’
actionpack (3.2.8) lib/action_controller/metal/instrumentation.rb:29:in
process_action' actionpack (3.2.8) lib/action_controller/metal/params_wrapper.rb:207:inprocess_action’
activerecord (3.2.8)
lib/active_record/railties/controller_runtime.rb:18:in process_action' actionpack (3.2.8) lib/abstract_controller/base.rb:121:inprocess’
actionpack (3.2.8) lib/abstract_controller/rendering.rb:45:in process' actionpack (3.2.8) lib/action_controller/metal.rb:203:indispatch’
actionpack (3.2.8) lib/action_controller/metal/rack_delegation.rb:14:in
dispatch' actionpack (3.2.8) lib/action_controller/metal.rb:246:inblock in
action’
actionpack (3.2.8) lib/action_dispatch/routing/route_set.rb:73:in call' actionpack (3.2.8) lib/action_dispatch/routing/route_set.rb:73:indispatch’
actionpack (3.2.8) lib/action_dispatch/routing/route_set.rb:36:in call' journey (1.0.4) lib/journey/router.rb:68:inblock in call’
journey (1.0.4) lib/journey/router.rb:56:in each' journey (1.0.4) lib/journey/router.rb:56:incall’
actionpack (3.2.8) lib/action_dispatch/routing/route_set.rb:600:in
call' actionpack (3.2.8) lib/action_dispatch/middleware/best_standards_support.rb:17:incall’
rack (1.4.1) lib/rack/etag.rb:23:in call' rack (1.4.1) lib/rack/conditionalget.rb:35:incall’
actionpack (3.2.8) lib/action_dispatch/middleware/head.rb:14:in call' actionpack (3.2.8) lib/action_dispatch/middleware/params_parser.rb:21:incall’
actionpack (3.2.8) lib/action_dispatch/middleware/flash.rb:242:in call' rack (1.4.1) lib/rack/session/abstract/id.rb:205:incontext’
rack (1.4.1) lib/rack/session/abstract/id.rb:200:in call' actionpack (3.2.8) lib/action_dispatch/middleware/cookies.rb:339:incall’
activerecord (3.2.8) lib/active_record/query_cache.rb:64:in call' activerecord (3.2.8) lib/active_record/connection_adapters/abstract/connection_pool.rb:473:incall’
actionpack (3.2.8) lib/action_dispatch/middleware/callbacks.rb:28:in
block in call' activesupport (3.2.8) lib/active_support/callbacks.rb:405:in_run__3479256987463636693__call__4454778504255292268__callbacks’
activesupport (3.2.8) lib/active_support/callbacks.rb:405:in
__run_callback' activesupport (3.2.8) lib/active_support/callbacks.rb:385:in_run_call_callbacks’
activesupport (3.2.8) lib/active_support/callbacks.rb:81:in
run_callbacks' actionpack (3.2.8) lib/action_dispatch/middleware/callbacks.rb:27:incall’
actionpack (3.2.8) lib/action_dispatch/middleware/reloader.rb:65:in
call' actionpack (3.2.8) lib/action_dispatch/middleware/remote_ip.rb:31:incall’
actionpack (3.2.8)
lib/action_dispatch/middleware/debug_exceptions.rb:16:in call' actionpack (3.2.8) lib/action_dispatch/middleware/show_exceptions.rb:56:incall’
railties (3.2.8) lib/rails/rack/logger.rb:26:in call_app' railties (3.2.8) lib/rails/rack/logger.rb:16:incall’
actionpack (3.2.8) lib/action_dispatch/middleware/request_id.rb:22:in
call' rack (1.4.1) lib/rack/methodoverride.rb:21:incall’
rack (1.4.1) lib/rack/runtime.rb:17:in call' activesupport (3.2.8) lib/active_support/cache/strategy/local_cache.rb:72:incall’
rack (1.4.1) lib/rack/lock.rb:15:in call' actionpack (3.2.8) lib/action_dispatch/middleware/static.rb:62:incall’
railties (3.2.8) lib/rails/engine.rb:479:in call' railties (3.2.8) lib/rails/application.rb:223:incall’
rack (1.4.1) lib/rack/content_length.rb:14:in call' railties (3.2.8) lib/rails/rack/log_tailer.rb:17:incall’
rack (1.4.1) lib/rack/handler/webrick.rb:59:in service' /Users/ogonbat/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:138:inservice’
/Users/ogonbat/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:94:in
run' /Users/ogonbat/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/server.rb:191:inblock in start_thread’

this are the request parameters

{“utf8”=>“✓”,
“authenticity_token”=>“g44p+IPxvdm2ouGAE2u2dV/cCKK8uF6G3XLL4z26zrI=”,
“page”=>{“title”=>“zfdzfdsf”,
“contents”=>{“short_description”=>“

sdfdsf

”,
“large_description”=>“

dsfdsf

”}},
“commit”=>“Create”}

First of all, sorry if this is a stupid question , but i have spent a
lot
of hours find in google a solution without any result.
thank’s in advance for your help