_form.html.haml

= semantic_form_for [@goal, @step], :url => goal_step_path(@goal, @step) do |f|
  = f.inputs :id => "step_#{@step.id}_description", :class => "description" do
    = f.input :description, :input_html => { :autofocus => "autofocus"}
  = f.inputs :date_due, :as => :string, :for => :due_date, :input_html => { :class => "datepicker"}, :label => "Due Date"
  = f.buttons do
    = f.commit_button
    or
    = link_to "Cancel", "#goal_#{@goal.id}", :class => "step_edit_cancel"

due_date.rb

class DueDate < ActiveRecord::Base
  belongs_to :step
end

my error

ActiveRecord::StatementInvalid in Steps#edit

Showing /Users/dc/launchtools/app/views/steps/_form.html.haml where line #4 raised:

SQLite3::SQLException: no such column: due_dates.one_time_id: SELECT  "due_dates".* FROM "due_dates" WHERE ("due_dates".one_time_id = 121) LIMIT 1
Extracted source (around line #4):

one_time.rb

class OneTime < Step
  has_one :due_date
  accepts_nested_attributes_for :due_date
end

step.rb

class Step < ActiveRecord::Base
  belongs_to :goal
end