Simple rails association - ruby-on-rails

Question

I'm  new to RoR. I'm trying to create a basic web app where a Profile page shows a list of Items, which belongs to a specific profile.
So far I have:
rails generate scaffold Profile name:string
rails generate scaffold Item description:string
rake db:migrate
In the profile model: has_many :items In the item model: belongs_to :profile
When I try to create a new profile, I get the error:
undefined method `item' for #<Profile
Profile controller
class ProfilesController < ApplicationController
# GET /profiles
# GET /profiles.json
def index
#profiles = profile.all
respond_to do |format|
format.html # index.html.erb
format.json { render json: #profiles }
end
end
# GET /profiles/1
# GET /profiles/1.json
def show
#profile = profile.find(params[:id])
respond_to do |format|
format.html # show.html.erb
format.json { render json: #profile }
end
end
# GET /profiles/new
# GET /profiles/new.json
def new
#profile = profile.new
respond_to do |format|
format.html # new.html.erb
format.json { render json: #profile }
end
end
# GET /profiles/1/edit
def edit
#profile = profile.find(params[:id])
end
# POST /profiles
# POST /profiles.json
def create
#profile = profile.new(params[:profile])
respond_to do |format|
if #profile.save
format.html { redirect_to #profile, notice: 'profile was successfully created.' }
format.json { render json: #profile, status: :created, location: #profile }
else
format.html { render action: "new" }
format.json { render json: #profile.errors, status: :unprocessable_entity }
end
end
end
# PUT /profiles/1
# PUT /profiles/1.json
def update
#profile = profile.find(params[:id])
respond_to do |format|
if #profile.update_attributes(params[:profile])
format.html { redirect_to #profile, notice: 'profile was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: "edit" }
format.json { render json: #profile.errors, status: :unprocessable_entity }
end
end
end
# DELETE /profiles/1
# DELETE /profiles/1.json
def destroy
#profile = profile.find(params[:id])
#profile.destroy
respond_to do |format|
format.html { redirect_to profiles_url }
format.json { head :no_content }
end
end
end
Profile index.html.erb
<h1>Listing profiles</h1>
<table>
<tr>
<th>Name</th>
<th></th>
<th></th>
<th></th>
</tr>
<% #profiles.each do |profile| %>
<tr>
<td><%= profile.name %></td>
<td><%= link_to 'Show', profile %></td>
<td><%= link_to 'Edit', edit_profile_path(profile) %></td>
<td><%= link_to 'Destroy', profile, method: :delete, data: { confirm: 'Are you sure?' } %></td>
</tr>
<% end %>
</table>
<br />
<%= link_to 'New profile', new_profile_path %>
Profile _show.html.erb
<%= simple_form_for(#profile) do |f| %>
<%= f.error_notification %>
<div class="form-inputs">
<%= f.input :name %>
</div>
<div class="form-inputs">
<%= f.input :item %>
</div>
<div class="form-actions">
<%= f.button :submit %>
</div>
<% end %>
Full error trace:
activemodel (3.2.12) lib/active_model/attribute_methods.rb:407:in `method_missing'
activerecord (3.2.12) lib/active_record/attribute_methods.rb:149:in `method_missing'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1161:in `value_before_type_cast'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1149:in `value_before_type_cast'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1043:in `block in to_input_field_tag'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1043:in `fetch'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1043:in `to_input_field_tag'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:692:in `text_field'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1284:in `text_field'
simple_form (2.1.0) lib/simple_form/inputs/string_input.rb:13:in `input'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:29:in `block in render'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:27:in `each'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:27:in `render'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:29:in `block in render'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:27:in `each'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:27:in `render'
simple_form (2.1.0) lib/simple_form/wrappers/root.rb:15:in `render'
simple_form (2.1.0) lib/simple_form/form_builder.rb:117:in `input'
app/views/profiles/_form.html.erb:9:in `block in _app_views_profiles__form_html_erb___911765346923063960_2183588380'
actionpack (3.2.12) lib/action_view/helpers/capture_helper.rb:40:in `block in capture'
actionpack (3.2.12) lib/action_view/helpers/capture_helper.rb:187:in `with_output_buffer'
actionpack (3.2.12) lib/action_view/helpers/capture_helper.rb:40:in `capture'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:607:in `fields_for'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:378:in `form_for'
simple_form (2.1.0) lib/simple_form/action_view_extensions/form_helper.rb:29:in `block in simple_form_for'
simple_form (2.1.0) lib/simple_form/action_view_extensions/form_helper.rb:48:in `with_simple_form_field_error_proc'
simple_form (2.1.0) lib/simple_form/action_view_extensions/form_helper.rb:28:in `simple_form_for'
app/views/profiles/_form.html.erb:1:in `_app_views_profiles__form_html_erb___911765346923063960_2183588380'
actionpack (3.2.12) lib/action_view/template.rb:145:in `block in render'
activesupport (3.2.12) lib/active_support/notifications.rb:125:in `instrument'
actionpack (3.2.12) lib/action_view/template.rb:143:in `render'
actionpack (3.2.12) lib/action_view/renderer/partial_renderer.rb:265:in `render_partial'
actionpack (3.2.12) lib/action_view/renderer/partial_renderer.rb:238:in `block in render'
actionpack (3.2.12) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.12) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionpack (3.2.12) lib/action_view/renderer/partial_renderer.rb:237:in `render'
actionpack (3.2.12) lib/action_view/renderer/renderer.rb:41:in `render_partial'
actionpack (3.2.12) lib/action_view/helpers/rendering_helper.rb:27:in `render'
app/views/profiles/new.html.erb:3:in `_app_views_profiles_new_html_erb___3444063506780261827_2182112400'
actionpack (3.2.12) lib/action_view/template.rb:145:in `block in render'
activesupport (3.2.12) lib/active_support/notifications.rb:125:in `instrument'
actionpack (3.2.12) lib/action_view/template.rb:143:in `render'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:47:in `block (2 levels) in render_template'
actionpack (3.2.12) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.12) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:46:in `block in render_template'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:54:in `render_with_layout'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:45:in `render_template'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:18:in `render'
actionpack (3.2.12) lib/action_view/renderer/renderer.rb:36:in `render_template'
actionpack (3.2.12) lib/action_view/renderer/renderer.rb:17:in `render'
actionpack (3.2.12) lib/abstract_controller/rendering.rb:110:in `_render_template'
actionpack (3.2.12) lib/action_controller/metal/streaming.rb:225:in `_render_template'
actionpack (3.2.12) lib/abstract_controller/rendering.rb:103:in `render_to_body'
actionpack (3.2.12) lib/action_controller/metal/renderers.rb:28:in `render_to_body'
actionpack (3.2.12) lib/action_controller/metal/compatibility.rb:50:in `render_to_body'
actionpack (3.2.12) lib/abstract_controller/rendering.rb:88:in `render'
actionpack (3.2.12) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:40:in `block (2 levels) in render'
activesupport (3.2.12) lib/active_support/core_ext/benchmark.rb:5:in `block in ms'
/usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/benchmark.rb:295:in `realtime'
activesupport (3.2.12) lib/active_support/core_ext/benchmark.rb:5:in `ms'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:40:in `block in render'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:83:in `cleanup_view_runtime'
activerecord (3.2.12) lib/active_record/railties/controller_runtime.rb:24:in `cleanup_view_runtime'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:39:in `render'
actionpack (3.2.12) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (3.2.12) lib/action_controller/metal/mime_responds.rb:196:in `respond_to'
app/controllers/profiles_controller.rb:29:in `new'
actionpack (3.2.12) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.2.12) lib/abstract_controller/base.rb:167:in `process_action'
actionpack (3.2.12) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (3.2.12) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.2.12) lib/active_support/callbacks.rb:414:in `_run__312850119216024862__process_action__607287929354052739__callbacks'
activesupport (3.2.12) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.12) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
activesupport (3.2.12) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.12) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.2.12) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.2.12) lib/action_controller/metal/params_wrapper.rb:207:in `process_action'
activerecord (3.2.12) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (3.2.12) lib/abstract_controller/base.rb:121:in `process'
actionpack (3.2.12) lib/abstract_controller/rendering.rb:45:in `process'
actionpack (3.2.12) lib/action_controller/metal.rb:203:in `dispatch'
actionpack (3.2.12) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.2.12) lib/action_controller/metal.rb:246:in `block in action'
actionpack (3.2.12) lib/action_dispatch/routing/route_set.rb:73:in `call'
actionpack (3.2.12) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (3.2.12) lib/action_dispatch/routing/route_set.rb:36:in `call'
journey (1.0.4) lib/journey/router.rb:68:in `block in call'
journey (1.0.4) lib/journey/router.rb:56:in `each'
journey (1.0.4) lib/journey/router.rb:56:in `call'
actionpack (3.2.12) lib/action_dispatch/routing/route_set.rb:601:in `call'
warden (1.2.1) lib/warden/manager.rb:35:in `block in call'
warden (1.2.1) lib/warden/manager.rb:34:in `catch'
warden (1.2.1) lib/warden/manager.rb:34:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.4.5) lib/rack/etag.rb:23:in `call'
rack (1.4.5) lib/rack/conditionalget.rb:25:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/head.rb:14:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/flash.rb:242:in `call'
rack (1.4.5) lib/rack/session/abstract/id.rb:210:in `context'
rack (1.4.5) lib/rack/session/abstract/id.rb:205:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/cookies.rb:341:in `call'
activerecord (3.2.12) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.2.12) lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.12) lib/active_support/callbacks.rb:405:in `_run__1382692569756144731__call__1219384665416315194__callbacks'
activesupport (3.2.12) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.12) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.12) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.12) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.12) lib/rails/rack/logger.rb:32:in `call_app'
railties (3.2.12) lib/rails/rack/logger.rb:16:in `block in call'
activesupport (3.2.12) lib/active_support/tagged_logging.rb:22:in `tagged'
railties (3.2.12) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.4.5) lib/rack/methodoverride.rb:21:in `call'
rack (1.4.5) lib/rack/runtime.rb:17:in `call'
activesupport (3.2.12) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.5) lib/rack/lock.rb:15:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/static.rb:62:in `call'
railties (3.2.12) lib/rails/engine.rb:479:in `call'
railties (3.2.12) lib/rails/application.rb:223:in `call'
rack (1.4.5) lib/rack/content_length.rb:14:in `call'
railties (3.2.12) lib/rails/rack/log_tailer.rb:17:in `call'
rack (1.4.5) lib/rack/handler/webrick.rb:59:in `service'
/usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'

Answer 1

In order for the has_many :items to work you will need to have a profile_id:integer in your Item model.
You can accomplish by doing the following command
rails g migration add_profile_id_to_items profile_id:integer
rake db:migrate
That should create the foreign key needed for the association.
After that you should be able to do things like this
#profile = Profile.create name: "MyProfile"
#item = #profile.items.build description: "This is my awesome item"
#item.save
There are different ways to create items for a profile but that's the most straight forward way. Then to retrieve those items you would do something like this
#profile = Profile.find(some_id)
#items = Item.where(profile_id: #profile.id).all
or
#profile = Profile.find(some_id)
#items = #profile.items

Answer 2

First of all, your Profile object does not have 'item' field.
Check your object's attributes by executing these commands:
rails console
Profile.connection
Profile
or visit your db/schema.rb file
You will see that there is no attribute :item in your object's hash.
You probably want to show the profile's items in your show.html.erb view. First though, you need to create an Item of the profile that it belongs to like so:
item = Item.new(description: "Test description", profile_id: 1)
Then you can do:
Profile.first.items
Second, you have an error in your controller. Object's class should be capitalized, so:
rails console
profile = profile.new(name: "Test profile")
will raise an error
undefined method `new' for nil:NilClass