My setup is as follows:
class User < ActiveRecord::Base
has_many :owners, :dependent => :destroy
has_many :properties, :through => :owners
end
class Owner < ActiveRecord::Base
belongs_to :user
belongs_to :property
end
class Property < ActiveRecord::Base
has_many :owners, :dependent => :destroy
has_many :users, :through => :owners
has_many :datafiles, :dependent => :destroy
end
class Datafile < ActiveRecord::Base
belongs_to :property
end
Now I'd like to be able to do #user.datafiles.
I tried has_many :datafiles, :through => :properties, :source => :datafiles but there appears to be a problem with a :through on something that's already went to a :through. So how would I go about to try and manage what I'm trying to do here?
Thank you in advance.
2 approaches;
1>
class User < AR
has_many :owners, :dependent => :destroy
has_many :properties, :through => :owners
has_many datafiles
end
class Datafile < AR
belongs_to :user
belongs_to :property
end
Your requirement of user.datafiles should be fulfilled with this.
If you want a nested has_many through, you'll need to use a plugin which is the 2nd approach.
2>
You can find it here.
The plugin works out of the box and does the job.
How about something like:
#user.rb
def datafiles
Property.find(:all, :joins => :owners, :conditions => ['owners.user_id = self.id'], :include => :datafile).collect(&:datafile)
Related
I am using Ruby on Rails 4.1 and I would like to implement a "direct" has_many association between Article and CommentRequest in the following case:
class Article < ActiveRecord::Base
has_many :comment_associations
has_many :comments, :through => :comment_associations
end
class Comment < ActiveRecord::Base
has_many :article_associations
has_many :articles, :through => :article_associations
has_many :comment_request_associations
has_many :comment_requests, :through => :comment_request_associations
end
class CommentRequest < ActiveRecord::Base
has_many :comment_associations
has_many :comments, :through => :comment_associations
end
That is, I would like to state a has_many association in both Article and CommentRequest in order to make it possible to run code as-like the following:
#article.comment_requests
#comment_request.articles
If it is possible, how to make that?
You should be able to do
class Article < ActiveRecord::Base
has_many :comment_associations
has_many :comments, :through => :comment_associations
has_many :comment_requests, :through => :comments
end
since rails allows you to nest has_many :through relationships
and similarly
class CommentRequest < ActiveRecord::Base
has_many :comment_associations
has_many :comments, :through => :comment_associations
has_many :articles, :through => :comments
end
I have models in my app:
class Comment < ActiveRecord::Base
belongs_to :commentable, :polymorphic => true
end
class Project < ActiveRecord::Base
has_many :discussions, :dependent => :destroy
has_many :tickets, :dependent => :destroy
end
class Discussion < ActiveRecord::Base
has_many :comments, :as => :commentable, :dependent => :destroy
end
class Ticket < ActiveRecord::Base
has_many :comments, :as => :commentable, :dependent => :destroy
end
Everything works fine, but sometimes it's not very convinient to get project from comment through commentable, i.e. comment.commentable.project.
Is there any way to make has_one project in Comment model?
I would add the following method to your class Comment:
def project
self.commentable ? self.commentable.project : nil
end
This will give you the same result without all the magic of ActivRecord.
I have simplified my design to make this question more clear. (Design of models below)
What I am trying to do is from a CourseEnrollment get all the PatientCourseSteps for that enrollment only (An enrollment consists of a patient and a course).
Here is what I have tried:
#Gives me ALL the patient course steps regardless of the course
course_enrollment.patient.patient_course_steps
#Gives me ALL the patient course steps regardless of the patient
course_enrollment.course.patient_course_steps
Below is the models that are necessary
class CourseEnrollment < ActiveRecord::Base
belongs_to :patient
belongs_to :course
end
class Course < ActiveRecord::Base
has_many :course_steps, :dependent => :destroy
has_many :steps, :through => :course_steps
has_many :course_enrollments, :dependent => :destroy
has_many :patients, :through =>:course_enrollments
has_many :patient_course_steps, :dependent => :destroy
end
class Patient < ActiveRecord::Base
belongs_to :user, :dependent => :destroy
has_many :enrollments, :dependent => :destroy
has_many :clients, :through => :enrollments
has_many :course_enrollments, :dependent => :destroy
has_many :courses, :through => :course_enrollments
has_many :patient_course_steps, :dependent => :destroy
end
class Step < ActiveRecord::Base
belongs_to :step_type
belongs_to :client
has_one :step_quiz, :dependent => :destroy
has_one :step_survey, :dependent => :destroy
has_one :step_text, :dependent => :destroy
has_one :step_download, :dependent => :destroy
has_one :step_video, :dependent => :destroy
has_one :step_presentation, :dependent => :destroy
has_many :course_steps, :dependent => :destroy
has_many :courses, :through => :course_steps
has_many :patient_course_steps, :dependent => :destroy
end
class PatientCourseStep < ActiveRecord::Base
belongs_to :patient
belongs_to :course
belongs_to :step
end
What I ended up doing was adding a method to CourseEnrollment named patient_course_steps which queries for what I need.
def patient_course_steps
PatientCourseStep.where(:patient_id => self.patient_id, :course_id => self.course_id)
end
I have the following models:
class User < ActiveRecord::Base
has_many :results, :dependent => :destroy
has_many :participants, :dependent => :destroy
has_many :courses, :through => :participants
end
class Course < ActiveRecord::Base
has_many :tests, :dependent => :destroy
has_many :participants, :dependent => :destroy
has_many :users, :through => :participants
end
class Result < ActiveRecord::Base
belongs_to :test
belongs_to :user
end
class Test < ActiveRecord::Base
belongs_to :course
has_many :results, :dependent => :destroy
end
The Idea is that a user has_and_belongs_to_many courses, the course has_many tests, and every test has_and_belongs_to_many users (results).
So what is the best query to select every Result from a single Course (not test), and also the query to select every Result from a single Course, but from one user.
Thanks!
To get the results from a specific course - given that the only bridge between the two is the test model you will need to include the test in the query.
Result.find(:all, :conditions => ["tests.course_id = ?",#course.id], :include => :test)
For the second query:
Result.find(:all, :conditions => ["user_id = ? AND tests.course_id = ?",#user.id, #course.id], :include => :test)
In my app I have the classes User, Video, and Vote. Users and Videos can relate to each other in two different ways: as a one-to-many or as a many-to-many. The former is when a User submits a Video (one user can submit many videos). The latter is when a user votes on a video (users have many videos through votes, and vice versa). Here is my code, which does not work (I think -- I may be doing something wrong in the view). Please help me understand the correct way to structure these associations:
class User < ActiveRecord::Base
has_many :videos, :as => :submissions
has_many :votes #have tried it without this
has_many :videos, :as => :likes, :through => :votes
end
class Vote < ActiveRecord::Base
belongs_to :video
belongs_to :user
end
class Video < ActiveRecord::Base
belongs_to :user
has_many :votes #have tried it without this . . . superfluous?
has_many :users, :as => :voters, :through => :votes
end
I haven't gone and checked, but it goes something like this:
Instead of
has_many :videos, :as => :likes, :through => :votes
Use
has_many :likes, :class_name => "Video", :through => :votes
Same with the bottom:
has_many :users, :as => :voters, :through => :votes
becomes
has_many :voters, :class_name => "User", :through => :votes
:as is used for polymorphic associations. See this chapter in docs for more info.
class User < ActiveRecord::Base
has_many :videos # Submitted videos
has_many :votes
has_many :voted_videos, :through => :votes # User may vote down a vid, so it's not right to call 'likes'
end
class Vote < ActiveRecord::Base
belongs_to :video
belongs_to :user
end
class Video < ActiveRecord::Base
belongs_to :user
has_many :votes
has_many :voters, :through => :votes
end
More details can be found here: http://guides.rubyonrails.org/association_basics.html
Hope it helps =)
Thanks for your help guys, definitely pointed me in the right direction. Here is the working code:
class User < ActiveRecord::Base
has_many :videos, :as => :submissions
has_many :votes
has_many :likes, :source => :video, :through => :votes
end
class Vote < ActiveRecord::Base
belongs_to :video
belongs_to :user
end
class Video < ActiveRecord::Base
belongs_to :user
has_many :votes
has_many :voters, :source => :user, :through => :votes
end
PS I kept it as :likes because in this app they won't be able to downvote, only upvote.