Is it possible to create form for simple class

Question

I just want to have ablility to edit class properties whish is not successor of ActiveRecord class.

Here is my class /app/model/entry.rb:

class Entry
  attr_accessor :title, :body
end

Here is a controller:

class DiaryController < ApplicationController
  def new
    @entry = Entry.new
  end
end

Here is a view:

<%= form_for(@entry) do |f| %>
<%= f.text_field :title %> <br />
<%= f.text_area :body %> <br />
<% end %>

I got the error message while I was opening form:

undefined method `model_name' for Entry:Class

Here is full stack:

Extracted source (around line #1):

1: <%= form_for(@entry) do |f| %>
2: <%= f.text_field :title %> <br />
3: <%= f.text_area :body %> <br />
4: <% end %>


Full trace:

activemodel (3.0.6) lib/active_model/naming.rb:95:in `model_name_from_record_or_class'
activemodel (3.0.6) lib/active_model/naming.rb:82:in `singular'
actionpack (3.0.6) lib/action_view/helpers/form_helper.rb:312:in `form_for'
app/views/diary/new.html.erb:1:in `_app_views_diary_new_html_erb___902027577_26033568_187052521'
actionpack (3.0.6) lib/action_view/template.rb:135:in `block in render'
activesupport (3.0.6) lib/active_support/notifications.rb:54:in `instrument'
actionpack (3.0.6) lib/action_view/template.rb:127:in `render'
actionpack (3.0.6) lib/action_view/render/rendering.rb:59:in `block in _render_template'
activesupport (3.0.6) lib/active_support/notifications.rb:52:in `block in instrument'
activesupport (3.0.6) lib/active_support/notifications/instrumenter.rb:21:in `instrument'
activesupport (3.0.6) lib/active_support/notifications.rb:52:in `instrument'
actionpack (3.0.6) lib/action_view/render/rendering.rb:56:in `_render_template'
actionpack (3.0.6) lib/action_view/render/rendering.rb:26:in `render'
actionpack (3.0.6) lib/abstract_controller/rendering.rb:115:in `_render_template'
actionpack (3.0.6) lib/abstract_controller/rendering.rb:109:in `render_to_body'
actionpack (3.0.6) lib/action_controller/metal/renderers.rb:47:in `render_to_body'
actionpack (3.0.6) lib/action_controller/metal/compatibility.rb:55:in `render_to_body'
actionpack (3.0.6) lib/abstract_controller/rendering.rb:102:in `render_to_string'
actionpack (3.0.6) lib/abstract_controller/rendering.rb:93:in `render'
actionpack (3.0.6) lib/action_controller/metal/rendering.rb:17:in `render'
actionpack (3.0.6) lib/action_controller/metal/instrumentation.rb:40:in `block (2 levels) in render'
activesupport (3.0.6) lib/active_support/core_ext/benchmark.rb:5:in `block in ms'
c:/Ruby192/lib/ruby/1.9.1/benchmark.rb:309:in `realtime'
activesupport (3.0.6) lib/active_support/core_ext/benchmark.rb:5:in `ms'
actionpack (3.0.6) lib/action_controller/metal/instrumentation.rb:40:in `block in render'
actionpack (3.0.6) lib/action_controller/metal/instrumentation.rb:78:in `cleanup_view_runtime'
activerecord (3.0.6) lib/active_record/railties/controller_runtime.rb:15:in `cleanup_view_runtime'
actionpack (3.0.6) lib/action_controller/metal/instrumentation.rb:39:in `render'
actionpack (3.0.6) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (3.0.6) lib/action_controller/metal/implicit_render.rb:5:in `send_action'
actionpack (3.0.6) lib/abstract_controller/base.rb:150:in `process_action'
actionpack (3.0.6) lib/action_controller/metal/rendering.rb:11:in `process_action'
actionpack (3.0.6) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.0.6) lib/active_support/callbacks.rb:436:in `_run__776311234__process_action__123531476__callbacks'
activesupport (3.0.6) lib/active_support/callbacks.rb:410:in `_run_process_action_callbacks'
activesupport (3.0.6) lib/active_support/callbacks.rb:94:in `run_callbacks'
actionpack (3.0.6) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.0.6) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.0.6) lib/active_support/notifications.rb:52:in `block in instrument'
activesupport (3.0.6) lib/active_support/notifications/instrumenter.rb:21:in `instrument'
activesupport (3.0.6) lib/active_support/notifications.rb:52:in `instrument'
actionpack (3.0.6) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.0.6) lib/action_controller/metal/rescue.rb:17:in `process_action'
actionpack (3.0.6) lib/abstract_controller/base.rb:119:in `process'
actionpack (3.0.6) lib/abstract_controller/rendering.rb:41:in `process'
actionpack (3.0.6) lib/action_controller/metal.rb:138:in `dispatch'
actionpack (3.0.6) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.0.6) lib/action_controller/metal.rb:178:in `block in action'
actionpack (3.0.6) lib/action_dispatch/routing/route_set.rb:62:in `call'
actionpack (3.0.6) lib/action_dispatch/routing/route_set.rb:62:in `dispatch'
actionpack (3.0.6) lib/action_dispatch/routing/route_set.rb:27:in `call'
rack-mount (0.6.14) lib/rack/mount/route_set.rb:148:in `block in call'
rack-mount (0.6.14) lib/rack/mount/code_generation.rb:93:in `block in recognize'
rack-mount (0.6.14) lib/rack/mount/code_generation.rb:68:in `optimized_each'
rack-mount (0.6.14) lib/rack/mount/code_generation.rb:92:in `recognize'
rack-mount (0.6.14) lib/rack/mount/route_set.rb:139:in `call'
actionpack (3.0.6) lib/action_dispatch/routing/route_set.rb:493:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/head.rb:14:in `call'
rack (1.2.2) lib/rack/methodoverride.rb:24:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/flash.rb:182:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/session/abstract_store.rb:149:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/cookies.rb:302:in `call'
activerecord (3.0.6) lib/active_record/query_cache.rb:32:in `block in call'
activerecord (3.0.6) lib/active_record/connection_adapters/abstract/query_cache.rb:28:in `cache'
activerecord (3.0.6) lib/active_record/query_cache.rb:12:in `cache'
activerecord (3.0.6) lib/active_record/query_cache.rb:31:in `call'
activerecord (3.0.6) lib/active_record/connection_adapters/abstract/connection_pool.rb:354:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/callbacks.rb:46:in `block in call'
activesupport (3.0.6) lib/active_support/callbacks.rb:416:in `_run_call_callbacks'
actionpack (3.0.6) lib/action_dispatch/middleware/callbacks.rb:44:in `call'
rack (1.2.2) lib/rack/sendfile.rb:107:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/show_exceptions.rb:47:in `call'
railties (3.0.6) lib/rails/rack/logger.rb:13:in `call'
rack (1.2.2) lib/rack/runtime.rb:17:in `call'
activesupport (3.0.6) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.2.2) lib/rack/lock.rb:11:in `block in call'
<internal:prelude>:10:in `synchronize'
rack (1.2.2) lib/rack/lock.rb:11:in `call'
actionpack (3.0.6) lib/action_dispatch/middleware/static.rb:30:in `call'
railties (3.0.6) lib/rails/application.rb:168:in `call'
railties (3.0.6) lib/rails/application.rb:77:in `method_missing'
railties (3.0.6) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.2.2) lib/rack/content_length.rb:13:in `call'
rack (1.2.2) lib/rack/handler/webrick.rb:52:in `service'
c:/Ruby192/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
c:/Ruby192/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
c:/Ruby192/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'

Is the ability to edit class properties using the form_for-tag?

Answer 1

jdc answered this, but didn't show the actual implementation you requested. As jdc stated you need to include some ActiveModel modules, which will give your ruby class the features you need.

It looks like you need ActiveModel::Naming and ActiveModel::AttributeMethods.

class Entry
  extend ActiveModel::Naming
  include ActiveModel::AttributeMethods
end

The first line will give you model_name and the second line allow your model to function with the form helpers. There are other lines you can use: check the blog posted linked in jdc's answer or the Rails API.

More links with detailed information:

http://www.rubyinside.com/rails-3-0s-activemodel-how-to-give-ruby-classes-some-activerecord-magic-2937.html

http://railscasts.com/episodes/219-active-model