From: "Éric DUMINIL" <eric.duminil@...>
Date: 2006-08-29T05:27:03+09:00
Subject: ActiveRecord, has_many and _count ...

Hi everybody!

Here are trunks of models from a little rails app I'm developing:

###########################
class Country < ActiveRecord::Base
  has_many :companies
........

###########################
class Category < ActiveRecord::Base
  has_many :companies
........

###########################
class Company < ActiveRecord::Base
  has_many :employees , :dependent => true 
  belongs_to :country, :counter_cache => true
  belongs_to :category, :counter_cache => true
........

###########################

class Employee < ActiveRecord::Base
  belongs_to :company, :counter_cache => true
........

###########################


I just would like to know: The right way to create a new company by updating 
Country.find(id).companies.size is by doing 
Country.find(id).companies.create . Right?

1) But what if I'd like to keep in cache companies.size for the category in 
which the new company is put? I can't create a company simultaneously using 
two parents!

2) When I edit the properties of a company, let's say moving from Japan to 
Italy, how could I update  Japan.companies_count and Italy.companies_count?
I tried to modify the update action of CompanieController:

###########################

  def update
    @company = Company.find(params[:id])
    @oldcountry=@company.country
    if @company.update_attributes(params[:company])
      @newcountry=@company.country
      @oldcountry.companies_count=@oldcountry.companies(:refresh).size
      @newcountry.companies_count=@newcountry.companies(:refresh).size
      flash[:notice] = 'Company was successfully updated.'
      redirect_to :action => 'show', :id => @company
    else
      render :action => 'edit'
    end
  end

###########################

but that did'nt work. :(


3) Is there a Rails' way to cache the number of Employees directly in 
Company.employees_count and Category.employees_count (i.e. through 
a "has_many_many" relation)? That would prevent iterating through every 
company of a given country/category to get its .employees_count!

Thanks a lot for your attention,

Have a good night,

Eric