gistfile1.txt

=form_for :company_branch do |f| 
  .field 
    .label Company Type
    .input=f.collection_select  :company_type_id, CompanyType.not_expired, :id, :name
  .field 
    .label Name
    .input=f.text_field :name 
  .field 
    .label Address
    .input=f.text_field :address 
  .field 
    .label Post Code
    .input=f.text_field :postcode 
  .field 
    .label Phone
    .input=f.text_field :phone 
  .field 
    .label Fax
    .input=f.text_field :fax 
  .field 
    .label Email
    .input=f.text_field :email 
  .field 
    .label Notes
    .input=f.text_area :notes , :rows=>10, :cols=>50
  .field 
    .label 
    .input=submit_tag "Save"


class CompanyBranchesController < ApplicationController

  .....

  def update
    @company_branch = CompanyBranch.find params[:id]
    if request.post?
      if @company_branch.update_attributes params[:company_branch]
        flash[:notice] = "Company updated."
        redirect_to :action=>"show", :id=>@company_branch 
      end
    end
  end

error : 

Couldn't find CompanyBranch without an ID
Parameters:

{"commit"=>"Save",
 "authenticity_token"=>"5MFAaxP+LiZmCGlLEKEAi1AADaqtcq8Sy0NXYd/FL68=",
 "utf8"=>"✓",
 "company_branch"=>{"name"=>"Chris' House",
 "address"=>"5 Lowerfold Drive,
 Rochdale,
 Lancashire",
 "company_type_id"=>"1",
 "postcode"=>"ol127ja",
 "notes"=>"Some notes here.",
 "phone"=>"09039093434",
 "fax"=>"343434",
 "email"=>"[email protected]"}}


Started POST "/company_branches/update" for 127.0.0.1 at Wed Jul 20 21:52:54 +0100 2011
  Processing by CompanyBranchesController#update as HTML
  Parameters: {"commit"=>"Save", "authenticity_token"=>"5MFAaxP+LiZmCGlLEKEAi1AADaqtcq8Sy0NXYd/FL68=", "utf8"=>"✓", "company_branch"=>{"name"=>"Chris' House", "address"=>"5 Lowerfold Drive, Rochdale, Lancashire", "company_type_id"=>"1", "postcode"=>"ol127ja", "notes"=>"Some notes here.", "phone"=>"09039093434", "fax"=>"343434", "email"=>"[email protected]"}}
  User Load (0.1ms)  SELECT `users`.* FROM `users` WHERE `users`.`id` = 1 LIMIT 1
Completed   in 25ms

ActiveRecord::RecordNotFound (Couldn't find CompanyBranch without an ID):
  app/controllers/company_branches_controller.rb:22:in `update'