undefined method `model_name' for Project:Class

Question

I've looked through all the related questions but nothing's new for me here.

I have a Project controller with "new" action

class ProjectsController < ApplicationController
  def new
    @newproject = Project.new
  end
end

Project is a simple class, not active record:

class Project
  attr_accessor :name, :description
  def initialize
    @name = ""
    @description = ""
  end
end

I get the error "undefined method `model_name' for Project:Class"

This is an erb file sample:

<%= form_tag(@newproject)  do |f| %>
  <%= f.label :name %>:
  <%= f.text_field :description %><br />
<% end %>

Answer 1

if Project is not an active record subclass, you need these and you can use form_for

class Project
  extend ActiveModel::Naming
  include ActiveModel::Conversion
  def persisted?
    false
  end
  ...
end

view:

<%= form_for(@newproject)  do |f| %>
  <%= f.label :name %>:
  <%= f.text_field :description %><br />
<% end %>

Answer 2

class Project < ActiveRecord::Base