undefined method `[]=' for nil:NilClass - ruby-on-rails

Question

I keep getting this undefined error when I try to submit this form with nested attributes, not sure where it's coming from been wrestling with it for quite a while now, I am trying to let users select an option in the council model the submit their choice, I am not sure if I have my associations wired up correctly or if the error is coming from the form. Am a noob to rails. Thanks in advance.
Error Updated
Properties::BuildController#update
app/controllers/properties/build_controller.rb, line 21
Started PUT "/properties/5/build/council" for 127.0.0.1 at 2013-08-18 08:52:07 +0100
Processing by Properties::BuildController#update as HTML
Parameters: {"utf8"=>"✓","authenticity_token"=>"wBWQaxtBioqzGLkhUrstqS+cFD/xvEutXnJ0jWNtSa0=", "council_id"=>"1", "commit"=>"Save changes", "property_id"=>"5", "id"=>"council"}
Property Load (0.2ms) SELECT "properties".* FROM "properties" WHERE "properties"."id" = ? LIMIT 1 [["id", "5"]]
Completed 500 Internal Server Error in 35ms
NoMethodError - undefined method `[]=' for nil:NilClass:
Council View
<h1>Select Council</h1>
<%= form_tag url_for(:action => 'update', :controller => 'properties/build'), :method => 'put' do %>
<%= select_tag :council_id, options_from_collection_for_select(Council.all, :id, :name) %>
<%= submit_tag %>
<% end %>
Controller
class Properties::BuildController < ApplicationController
include Wicked::Wizard
steps :tenant, :meter, :council, :confirmed
def show
#property = Property.find(params[:property_id])
#tenants = #property.tenants.new(params[:tenant_id])
#meter = #property.build_meter
#council = #property.build_council
render_wizard
end
def edit
#property = Property.find(params[:property_id])
end
def update
#property = Property.find(params[:property_id])
params[:property][:status] = step.to_s
params[:property][:status] = 'active' if step == steps.last
#property.update_attributes(params[:property])
render_wizard #property
end
end
Council.rb
class Council < ActiveRecord::Base
attr_accessible :CouncilEmail, :name, :CouncilTel
belongs_to :property
end
UPDATED Propery.rb
class Property < ActiveRecord::Base
attr_accessible :name, :address_attributes, :tenants_attributes, :meter_attributes, :council_attributes, :property_id, :status
belongs_to :user
has_one :address, :as => :addressable
accepts_nested_attributes_for :address, :allow_destroy => true
has_one :council
accepts_nested_attributes_for :council, :allow_destroy => true
has_many :tenants, :inverse_of => :property
accepts_nested_attributes_for :tenants, :allow_destroy => true, :reject_if => :all_blank
has_one :meter
accepts_nested_attributes_for :meter, :allow_destroy => true
validates :name, :presence => :true
validates :address, :presence => :true
validates :tenants, :presence => true, :if => :active_or_tenants?
validates :council, :presence => true, :if => :active_or_council?
def active?
status == 'active'
end
def active_or_tenants?
(status || '').include?('tenants') || active?
end
def active_or_council?
(status || '').include?('council') || active?
end
end

Answer 1

I think this
params[:property]
is nil. So Ruby complains when doing
params[:property][:status] = 'foo'
You might want to do something like this:
if params[:property]
params[:property][:status] = 'foo'
end
However in your case the issue is because you are using a form_tag instead of a form_for, therefor params[:property] is not defined.

Answer 2

A better approach to check for nested attributes in ruby hashes nowadays is to use dig
Example:
params.dig(:property, :status)
If the key is not defined nil is returned.

Answer 3

If using a data file, make sure there's not a stray - in the data.yml. See this GitHub comment