Rails STI

gistfile1.rb

# model finance.rb

class Finance < ActiveRecord::Base
  
  # Attributes
  attr_accessible :amount, :date, :description, :type

  # Associations
  belongs_to :users, :dependent => :destroy

end

# model expense.rb

class Expense < Finance; end

# model income.rb

class Income < Finance; end

# controller finances_controller.rb

class FinancesController < ApplicationController
  before_filter :authenticate_user!

  def index
    @finances = current_user.finances.all
    @finance_sum = current_user.finances.sum('amount')
  end

  def new
    @finance = Finance.new
  end

  def create
    @finance = Finance.new(params[:finance])
    @finance.user_id = current_user
    @finance.type = params[:finance_type]   
    if @finance.save
       redirect_to finances_path notice: 'Item created.'
    else
       render action: "new"
    end    
  end
end

# view _form.html.erb

<%= form_for @finance do |f| %>
  <%= select_tag(:finance_type, options_for_select([['Income'], ['Expense']])) %>
  <div class="field">
    <%= f.label :description %><br />
    <%= f.text_field :description %>
  </div>
  <div class="field">
    <%= f.label :amount %><br />
    <%= f.number_field :amount %>
  </div>
  <div class="field">
    <%= f.label :date %><br />
    <%= date_select :finance, :date %>
  </div>
  <div class="actions">
    <%= f.submit "Save" %>
  </div>
<% end %>