rubyonrailsin

On Tue, Mar 30, 2010 at 3:03 PM, khagimoto <kumi.hagimoto@gmail.com> wrote:
> I'm trying to replicate a join in RoR that I can do in SQL very
> simply.
>
> Three tables/models that I have are: Users, Users_Activities,
> Activities and Codes.
>
> Users and Activities have appropriate has_many associations through
> Users_Activities model, so it's easy to do a join to get all
> activities for a given user.
>
> Codes, on the other hand, is a different story.  It's kind of a
> "repository" of all codified data.  For example, the Activity table
> has a "Activity Type" field that is an integer field.  To get the
> actual Activity Type name, you have to look it up in the Codes table
> like so (joining with user table to get all activities for user id
> "1"):
>
> select activities.*, codes.name from activities, users_activities,
> codes
> where users_activities.user_id = 1
>   and users_activities.activity_id = activities.id
>   and activities.activity_type = codes.id
>
> I can do part of the above query if i don't include the Codes table
> like so:
>
> Activity.all(:joins => :users_activities, :conditions =>
> {'users_activities.user_id' => "1"})
>
> How do I also join Codes?

class User < AcrtiveRecord::Base
has_many :user_activities
end

class UserActivity < ActiveRecord::Base
belongs_to :user
belongs_to :code, :foreign_key => "activity_type"
end

Activity.find_all_by_user_id(1, :include => :code)

This will return a collection of all of the activities for user#1 with
attached instances of the code for each activity

--
Rick DeNatale

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