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)
Related
Let's say we have a User.
A user has_many documents through account like so…
class User < ActiveRecord::Base
belongs_to :account
has_many :documents, :through => :account, :order => "created_at DESC"
end
class Account < ActiveRecord::Base
has_one :owner, :class_name => "User", :dependent => :destroy
has_many :documents, :dependent => :destroy
end
class Document < ActiveRecord::Base
belongs_to :account
end
Nice and simple, this is where it gets tricky…
A user can also collaborate on documents, this via the collaborators join table…
class Collaborator < ActiveRecord::Base
belongs_to :user
belongs_to :documnet
end
class Document < ActiveRecord::Base
has_many :collaborators, :dependent => :destroy
has_many :users, :through => :collaborators
accepts_nested_attributes_for :collaborators, :allow_destroy => true
end
The final user bit of this is what i'm not sure about. I want to add another has many documents, and when you call user.documents it blends both documents via their account and the ones they're collaborating on…
class User < ActiveRecord::Base
belongs_to :account
has_many :documents, :through => :account, :order => "created_at DESC"
#documents need to do both has manys…
has_many :collaborators, :dependent => :destroy
has_many :documents, :through => :collaborators
end
Thanks, it's a bit long but I can think of a neat solution. Any help would be much appreciated.
You can create a method that will request on the tables documents, accounts and collaborators to find the documents related to the user:
class User < ActiveRecord::Base
#...
def documents
Document.includes(:account, :collaborators).where('collaborators.user_id = ? OR documents.account_id = ?', self.id, self.account.id)
end
end
I've not tested this request, but I hope you get the idea. Please correct it if it's erroneous.
For the 2 has_many documents, :through..., you can remove them if you don't need them anymore; Otherwise, you have to give them different names (and different from the method above).
I need to write a scope that I will pass a user's id through and will collect all the user's list associates with all the companies for that user from the users table.
In User.rb:
has_many :employments
has_many :companies, :through => :employments, :dependent => :destroy
...
In Employment.rb:
belongs_to :user
belongs_to :company
In Company.rb:
has_many :employments
has_many :users, :through => :employments, :dependent => :destroy
This could be possible using something like:
current_user.companies.each{|c| c.users.each {|u| u}}
but writing like this I think is much more time consuming.
The following (not tested) scope finds all companies where a given user had work.
class Company
has_many :employments
has_many :users, :through => :employments, :dependent => :destroy
scope :with_user, lambda { |user_id| joins(:employments).where(:user => user_id) }
...
Run rails c and execute try Company.with_user(User.last!.id) and see what happens.
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)
I have a models User
class User < ActiveRecord::Base
has_many :ratings
has_many :rated_films, :through => :ratings, :source => :film
end
and Films
class Film < ActiveRecord::Base
has_many :users, :through => :ratings
end
I am looking to find all Films that have not been rated by the specified user, smth like
class Film < ActiveRecord::Base
has_many :users, :through => :ratings
named_scope :not_rated_by_user, lambda { |user|
{:joins => :users, :conditions => ['? NOT IN users', user]}
}
end
Film.not_rated_by_user(User.first)
I am not that familiar with SQL so am not quite sure if this could be achieved in a named scope.
Many thanks
Yuriy
I suppose you have a ratings table, which is your join table. Right? So you need something like:
class User < ActiveRecord::Base
has_many :ratings
has_many :rated_films, :through => :ratings, :source => :film
end
class Film < ActiveRecord::Base
has_many :ratings
has_many :users, :through => :ratings
named_scope :not_rated_by_user, lambda { |user_id| {
:include => :ratings,
:conditions => ['? NOT IN (ratings.user_id)', user_id]
}}
end
class Rating < ActiveRecord::Base
belongs_to :film
belongs_to :user
end
And you can use
Film.not_rated_by_user(User.first.id)
Please let me know if it helped. I haven't tested!
I have a User Model(:name, :password, :email), and Event model(:name, :etc) and Interest model (:name) [>all singular<]
Then I created two join tables -> UsersInterests and EventsInterests; each not containing a primary key and only comprised of the user_id/interest_id and event_id/interest_id respectively. [>plural<]
My Models Use the Nested Has Many Through Plugin
user.rb => has_many :users_interests
has_many :interests, :through => :users_interests
has_many :events_interests, :through => :interests
has_many :events, :through => :events_interests
event.rb => has_many :events_interests
has_many :interests, :through => :events_interests
has_many :users_interests, :through => :interests
has_many :users, :through => :users_interests
interest.rb => has_and_belongs_to_many :users
has_and_belongs_to_many :events
events_interests.rb => belongs_to :interests
belongs_to :events
users_interests.rb => belongs_to :users
belongs_to :interests
Whew..ok So I wanted to created a named_scope of that find all the events that share interest with a particular user. Here is some code someone helped me with.
named_scope :shares_interest_with_users, lambda {|user|
{ :joins => :users_interests,
:conditions => {:users_interests => {:user_id => user}}
}}
When i run from the controller =>
#user = User.find(1)
#events = Event.shares_interest_with_user(#user)
I get the error :
uninitialized constant Event::EventsInterest
Can anyone see what i messed up?
You must have named something wrong along the way. At a glance I'd say you have a file or class named incorrectly. Remember model names MUST always be singular, both in file and class names or else Rails won't make the connection. Another source of your problem is that arguments to belongs_to must also be singular. Even if you had got things right, the HABTM relationship in interests with users would have thrown an error when you ran the named scope.
I was able to solve your error with the following models.
user.rb
class User < ActiveRecord::Base
has_many :users_interests
has_many :interests, :through => :users_interests
has_many :events_interests, :through => :interests
has_many :events, :through => :events_interests
end
users_interest.rb
class UsersInterest < ActiveRecord::Base
belongs_to :user
belongs_to :interest
end
interest.rb
class Interest < ActiveRecord::Base
has_many :users,:through => :users_interests
has_many :users_interests
has_many :events_interests
has_many :events, :through => :events_interests
end
**events_interest.rb
class EventsInterest <ActiveRecord::Base
belongs_to :interest
belongs_to :event
end
event.rb
class Event <ActiveRecord::Base
has_many :events_interests
has_many :interests, :through => :events_interests
has_many :users_interests, :through => :interests
has_many :users, :through => :users_interests
named_scope :shares_interest_with_users, lambda {|user|
{ :joins => :users_interests,
:conditions => {:users_interests => {:user_id => user}}
}
}
end