Has_many through question

I have made 3 tables

±-----------+ ±---------------+ ±-----------+
|people | |people_campaigns| |campaigns |
±-----------+ ±---------------+ ±-----------+
|id :int | <----> |people_id :int | /-> |id :int |
|name :string| |campaign_id :int| <-/ |name :string|
|etc … | |exported :int | |desc :string|
±-----------+ ±---------------+ ±-----------+

The people model looks like this

has_many :people_campaigns
has_many :campaigns, :through => :people_campaigns

the other models I left empty because there is no need for me to work
the other way I think

What I want to do is make an export of all people that are in campaign
“x” and are not yet exported. If they are exported then update with
people_campaigns.exported=1

what I did is (except for the fastercsv lines):

people = Person.find(:all)
people.each do |person|
campaigns = person.campaign
campaings.each do |campaign|
if campaign.name == params[:campaignName]
tester = PeopleCampaign.find(:first,
:conditions => [“person_id=? and
campaign_id=? and isnull(exported)”,person.id,campaign.id]
)
if tester
#print all to fastercsvlines
tester.exported = 1
tester.save
end
end
end
end

This part is out of the top of my head but I don’t like this code and I
think there is a nicer and better (ruby on rails) way to do this ???
especially the part where i lookup the peoplecampaign record for which i
had to add an id (yeah didn’t mention it in the table layout)

On Feb 12, 11:00 am, Daniel Van den oord <rails-mailing-l…@andreas-
s.net> wrote:

The people model looks like this

has_many :people_campaigns
has_many :campaigns, :through => :people_campaigns

One thing which I notice is that you have two options:

has_many :campaigns, :through => relationships

(choose a better model name than “relationship”)

Or:

has_and_belongs to :campaigns_people

with campaigns first.

At least, that’s my understanding. I don’t think that there’s
anything technically wrong for a hmt relationship to use
“campaigns_people”, but it’s not the convention.

-Thufir

My main problem is with the part that it loops twice and does a seperate
lookup. I am worried that this had major performance problems because
the Person table will hold 1.2 million records and at least 700.000
people per campaigns there will be 4 at least this means that the
people_campaigns table will grow to about 2.8 million records and
perhaps more

The naming convention I got from the rails wiki but I will look into
this however this isn’t really the problem

On 2/13/08, Daniel Van den oord [email protected]
wrote:

My main problem is with the part that it loops twice and does a seperate
lookup. I am worried that this had major performance problems because
the Person table will hold 1.2 million records and at least 700.000
people per campaigns there will be 4 at least this means that the
people_campaigns table will grow to about 2.8 million records and
perhaps more

The naming convention I got from the rails wiki but I will look into
this however this isn’t really the problem

Let’s set this up conventionally:

class Person < ActiveRecord::Base
has_many :campaigns :through => :campaign_enrollments
has_many :campaign_enrollments

The people table needs at least id as well as any other attributes.

end

class CampaignEnrollment
belongs_to :person
belongs_to :campaign

The campaign_enrollments table needs at least id, person_id,

campaign_id and exported fields.
end

class Campaign
has_many :campaign_enrollments
has_many :people :through => :campaign_enrollments

the campaigns table needs at least id field plus other campaign

attributes.
end

Now given a campaign

campaign = Campaign.find(…)

campaign.campaign_enrollments.find(:all, :include => [:people,
;campaigns] :conditions => [“exported !=?”, true]).each do |
campaign_enrollment|
# whatever exporting does here
campaign_enrollment.update_attribute(:exported, true)
end

Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

If I understood it correctly…
almost eveything that can be in the controller can be done in the view
(with some exceptions)

however this example is being used for an import and export
the export doesn’t have a view I use fastercsv to generate a csv file
streaming to the browser…

Thufir wrote:

On Feb 13, 3:13 pm, “Rick DeNatale” [email protected] wrote:
[…]

campaign.campaign_enrollments.find(:all, :include => [:people,
;campaigns] :conditions => [“exported !=?”, true]).each do |
campaign_enrollment|
# whatever exporting does here
campaign_enrollment.update_attribute(:exported, true)
end
[…]

This sort of iteration couldn’t go in the controller, could it? It
would have to go in the view?

-Thufir

On Feb 13, 3:13 pm, “Rick DeNatale” [email protected] wrote:
[…]

campaign.campaign_enrollments.find(:all, :include => [:people,
;campaigns] :conditions => [“exported !=?”, true]).each do |
campaign_enrollment|
# whatever exporting does here
campaign_enrollment.update_attribute(:exported, true)
end
[…]

This sort of iteration couldn’t go in the controller, could it? It
would have to go in the view?

-Thufir

On 13 Feb 2008, at 15:13, Rick DeNatale wrote:

perhaps more

The people table needs at least id as well as any other

class Campaign
campaign.campaign_enrollments.find(:all, :include => [:people,
;campaigns] :conditions => [“exported !=?”, true]).each do |
campaign_enrollment|
# whatever exporting does here
campaign_enrollment.update_attribute(:exported, true)
end

it might be nice to add

has_many :unexported_enrollments, :conditions => [“exported != ?”,
true], :class_name => “CampaignEnrollment”
to campaign.

you could then write

campaign.unexported_enrollments.find :all, :include => […] do |
campaign_enrollment|

end

This will do exactly the same thing, but can make things so much more
readable.

Fred

On Thu, Feb 14, 2008 at 10:05 AM, Daniel Van den oord
[email protected] wrote:

If I understood it correctly…
almost eveything that can be in the controller can be done in the view
(with some exceptions)

But it really should be done in the model, with a method used to allow
the controller to trigger it.

Putting too much business logic in a controller is a bad code smell.

Putting too much logic in views is an even bigger bad code smell.

http://weblog.jamisbuck.org/2006/10/18/skinny-controller-fat-model

Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

On Thu, Feb 14, 2008 at 10:15 AM, Frederick C.
[email protected] wrote:

it might be nice to add
has_many :unexported_enrollments, :conditions => [“exported != ?”,
true], :class_name => “CampaignEnrollment”
to campaign.

or even

has_many :enrollments, :class_name => “CampaignEnrollment” do
def unexported
find(:all, :conditions => [“exported !=>”, true]
end

Which would allow

campaign.enrollments.unexported.each do | enrollment |

has_many :enrollments

My blog on Ruby
http://talklikeaduck.denhaven2.com/


Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/