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


 

I think you want the Rails mailing list...

Max

On 8/29/06, =C9ric DUMINIL <eric.duminil@gmail.com> wrote:
> 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 =3D> true
>   belongs_to :country, :counter_cache =3D> true
>   belongs_to :category, :counter_cache =3D> true
> ........
>
> ###########################
>
> class Employee < ActiveRecord::Base
>   belongs_to :company, :counter_cache =3D> true
> ........
>
> ###########################
>
>
> I just would like to know: The right way to create a new company by updat=
ing
> 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 usi=
ng
> two parents!
>
> 2) When I edit the properties of a company, let's say moving from Japan t=
o
> Italy, how could I update  Japan.companies_count and Italy.companies_coun=
t?
> I tried to modify the update action of CompanieController:
>
> ###########################
>
>   def update
>     @company =3D Company.find(params[:id])
>     @oldcountry=3D@company.country
>     if @company.update_attributes(params[:company])
>       @newcountry=3D@company.country
>       @oldcountry.companies_count=3D@oldcountry.companies(:refresh).size
>       @newcountry.companies_count=3D@newcountry.companies(:refresh).size
>       flash[:notice] =3D 'Company was successfully updated.'
>       redirect_to :action =3D> 'show', :id =3D> @company
>     else
>       render :action =3D> '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
>
>
>
>
>

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

�ric DUMINIL wrote:

> 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?

This is one way of doing it. Although if you have the id of the Country
you can just say:
  company = Company.create( :company_name=>'ABC Co', :country_id=>1 )
OR
  company = Company.new( :company_name=>'ABC Co', :country_id=>1 )
  company.save

Both of these will update the country countries_counter because you have
defined this in your belongs_to relationship.


> 
> 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!

This can be solved using create or save on Company itself, rather then
doing Country.find.companies.create. Since you have defined the
belongs_to relationship and specified the counter cache ActiveRecord
will be smart enough to update both of them. The following example will
work:
  Company.create :company_name=>'ABC', :country_id=>1, :category_id=>1
> 
> 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?

If you edit the properties of a company and save it ActiveRecord will
correctly increment/decrement the counter cache fields that you have
placed on your tables.

Using :refresh will ensure that you get the most recent data from the
database.

> 
> 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!

I don't know about the count via a another relationship, but you can
always count them at once rather then iterating over each company.

Category.count(
  :joins=>"INNER JOIN #{Company.table_name} ON " +
      "#{Company.table_name}.category_id=" +
      "#{Category.table_name}.id " +
      "INNER JOIN #{Employee.table_name} ON " +
      "#{Employee.table_name}.company_id=#{Company.table_name}.id",
  :group=>"#{Category.table_name}.id" )

This will give you an array of arrays, where each internal array is
employee_count, category_id:
  [ [ 4, 1 ], [ 2, 2 ], [ 30, 3 ] ]

It doesn't handle categories that do not have any employees although
that could be fixed.

This is perhaps not as simple of a solution you're looking for. Perhaps
someone else knows if you can do counter_cache using :through. ;)

Zach






-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.2.2 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFE86bfMyx0fW1d8G0RAukPAJ9h4COcF11Zrzo0AVqjV1t8Il1hjACfcbuQ
7Qqh6h2BI4zt9P8WjMq59cg=
=Nz8h
-----END PGP SIGNATURE-----

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

zdennis wrote:

> 
> This is one way of doing it. Although if you have the id of the Country
> you can just say:
>   company = Company.create( :company_name=>'ABC Co', :country_id=>1 )
> OR
>   company = Company.new( :company_name=>'ABC Co', :country_id=>1 )
>   company.save
> 
> Both of these will update the country countries_counter because you have
                                        ^^^^^^^^^^^^^^^
should be companies_counter. ;)

Zach
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.2.2 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFE86hbMyx0fW1d8G0RAsWHAJ0XsQqlFXZePu0A+xXdsw3FRn4DfQCfUAyX
xNpxNiX3RqhDAfutQC3Ud1k=
=P1Yo
-----END PGP SIGNATURE-----