I have an app with country preferences. A user will have 2 types of country preferences - event and research. In the future there may be more. I was leaning more towards having 2 tables to represent this over using STI. I'm having a bit of trouble configuring Rails elegantly to do this. I could hack it but I would rather do this by Rails convention. What I want is something like this:
class User < ActiveRecord::Base
has_many event_countries, :through => :event_countries, :class_name => 'Country'
has_many research_countries, :through => :research_countries, :class_name => 'Country'
end
class EventCountry < ActiveRecord::Base
belongs_to :country
belongs_to :user
end
class ResearchCountry < ActiveRecord::Base
belongs_to :country
belongs_to :user
end
class Country < ActiveRecord::Base
...
end
This doesn't work though. Given this "pseudo code" does anyone know how to actually implement this in Rails?
I think you're going about declaring them wrong, because this should work properly. That's what the :through directive is for:
class User < ActiveRecord::Base
has_many :event_countries
has_many :countries_with_events,
:through => :event_countries,
:source => :country
has_many :research_countries
has_many :countries_with_researches,
:through => :research_countries,
:source => :country
end
class EventCountry < ActiveRecord::Base
belongs_to :country
belongs_to :user
end
class ResearchCountry < ActiveRecord::Base
belongs_to :country
belongs_to :user
end
class Country < ActiveRecord::Base
# ...
end
A lot of the awkwardness comes from the labels you've chosen for the tables. Although they'd seem reasonable at first glance, the way you use them ends up making them difficult.
You might want to call research_countries something like user_research_countries so that the relationship name can be user.research_countries as the :through:
class User < ActiveRecord::Base
has_many :user_event_countries
has_many :event_countries,
:through => :user_event_countries,
:source => :country
has_many :user_research_countries
has_many :research_countries,
:through => :user_research_countries,
:source => :country
end
class UserEventCountry < ActiveRecord::Base
belongs_to :country
belongs_to :user
end
class UserResearchCountry < ActiveRecord::Base
belongs_to :country
belongs_to :user
end
class Country < ActiveRecord::Base
# ...
end
You can refactor this even further by adding a field to the user-country association table that includes one or more flags, which in this case would be research or event or whatever you require later:
class User < ActiveRecord::Base
has_many :user_countries
has_many :event_countries,
:through => :user_countries,
:source => :country,
:conditions => { :event => true }
has_many :research_countries,
:through => :user_countries,
:source => :country,
:conditions => { :research => true }
end
class UserCountry < ActiveRecord::Base
belongs_to :country
belongs_to :user
# * column :event, :boolean
# * column :research, :boolean
end
class Country < ActiveRecord::Base
# ...
end
Related
I am trying to transform my HABTM to has_many through relations. Sometimes I have to connect the same models in different ways. For example to specify different roles for authors.
With a HABTM I would do this through the declaration of a class_name option. Just like:-
class Project < ActiveRecord::Base
has_and_belongs_to_many :curators, :class_name => :author, :through => :projects_curators
end
class ProjectsCurator < ActiveRecord::Base
attr_accessible :project_id, :author_id
belongs_to :project
belongs_to :author
end
class Author < ActiveRecord::Base
has_and_belongs_to_many :projects, :through => :projects_curators
end
But when I transform everything into a has_many through:
class Project < ActiveRecord::Base
has_many :project_curators
has_many :curators, :class_name => :author, :through => :project_curators
end
class ProjectCurator < ActiveRecord::Base
attr_accessible :project_id, :author_id
belongs_to :project
belongs_to :author
end
class Author < ActiveRecord::Base
has_many :project_curators
has_many :projects, :through => :project_curators
end
I get: Could not find the source association(s) :curator or :curators in model ProjectCurator. Try 'has_many :curators, :through => :project_curators, :source => <name>'. Is it one of :author or :project?
When I add :source
has_many :curators, :class_name => :author, :through => :project_curators, :source => :author
I get:
uninitialized constant Project::author
How can I get this working? Thank you very much in advance!
Understanding :source option of has_one/has_many through of Rails should help you out
When you declare the source you're not declaring the class of the has_many relationship, but the name of the relationship you're using as the middle man. In your case, try:
has_many :curators, :through => :project_curators, :source => :author
As someone in the above post states:
Most simple answer - the name of the relationship in the middle
I feel a little out of my depth here. I've got the following relationships:
class User < ActiveRecord::Base
has_many :flights
end
class Flight < ActiveRecord::Base
has_many :flight_legs
belongs_to :user
end
class FlightLeg < ActiveRecord::Base
belongs_to :departure_airport, :class_name => "Airport"
belongs_to :arrival_airport, :class_name => "Airport"
end
class Airport < ActiveRecord::Base
belongs_to :country
has_many :flight_legs_arriving_here, :class_name => "FlightLeg",
:foreign_key => "arrival_airport_id"
has_many :flight_legs_departing_here, :class_name => "FlightLeg",
:foreign_key => "departure_airport_id"
end
class Country < ActiveRecord::Base
attr_accessible :name
has_many :airports
end
I want to get a list of users by the number of countries that they have visited, and a separate query which will return the number of countries a user has visited. Does anyone have any idea how to do this? I am sort of lost with the details of the documentation on this one.
My db schema:
tournaments(id, ...)
teams(tournament_id, id, ...)
matches(tournament_id, id, team_id_home, team_id_away, ...)
Models:
class Tournament < ActiveRecord::Base
has_many :teams, dependent: :destroy
has_many :matches, dependent: :destroy
...
end
class Team < ActiveRecord::Base
belongs_to :tournament
...
end
class Match < ActiveRecord::Base
belongs_to :tournament
has_many :teams
...
end
I would like to have the following data in my view:
match_id team_id_home team_id_away team_id_home_name team_id_away_name
So, I'm asking for help with the following query (I'm trying to get team's names, but having problem with joining):
#matches = #tournament.matches.where(:tournament => #tournament).joins(:teams).paginate(page: params[:page])
I'm fairly new to rails, but you should be able to setup your associations like this: (going from memory)
class Match < ActiveRecord::Base
belongs_to :tournament
has_one :home_team, :class_name => "Team", :foreign_key => "team_id_home"
has_one :away_team, :class_name => "Team", :foreign_key => "team_id_away"
end
#####
m = Match.first
m.away_team.team_name
m.home_tam.team_name
Or in your case:
#matches = #tournament.matches.paginate(page: params[:page])
I don't think you need the where function: the has_many association tells rails to only pull matching matches.
It is belongs_to, not has_one in Match model.
class Match < ActiveRecord::Base
belongs_to :tournament
belongs_to :home_team, :class_name => "Team", :foreign_key => "team_id_home"
belongs_to :away_team, :class_name => "Team", :foreign_key => "team_id_away"
end
class Team < ActiveRecord::Base
belongs_to :tournament
has_many :matches
end
Now I can use tournament.home_team.name in my view
Im setting up a reminder service that sends deals via email in relation to a persons interests AND city.. Basically, the user inputs important dates (friends bday, anniversary ect) and the interests of that special person.
I want to send them deals based on 1)the users city and 2)the interests of the related person
How should i setup my associations for the Deal model?
What i have so far..
class User < ActiveRecord::Base
belongs_to :city
has_many :person_interests, :as => :person
has_many :interests, :through => :person_interests
end
class City < ActiveRecord::Base
attr_accessible :name
belongs_to :province
has_many :users
end
class PersonInterest < ActiveRecord::Base
belongs_to :interest
belongs_to :person, :polymorphic => true
end
class Interest < ActiveRecord::Base
has_many :person_interests
end
Thanks!
If a deal could apply to more than one interest, you'd start with something like:
class Deal < ActiveRecord::Base
belongs_to :interests
belongs_to :city
end
class City < ActiveRecord::Base
attr_accessible :name
belongs_to :province
has_many :users
has_many :deals
end
class Interest < ActiveRecord::Base
has_many :person_interests
has_many :deals
end
And then you could do something like
#relevant_deals = #city.deals.where(:interest_id => 'abc')
or
#relevant_deals = #interest.deals.where(:city_id => 'def')
Right now I have a rich many-to-many association with VideoVote as the independent record.
class VideoVote < ActiveRecord::Base
belongs_to :user
belongs_to :video
end
class User < ActiveRecord::Base
has_many :video_votes
has_many :voted_videos,
:through => :video_votes,
:source => :video
end
class Video < ActiveRecord::Base
has_many :video_votes
has_many :voted_users,
:through => :video_votes,
:source => :user
end
However, I want to trasform this into a polymorphic association where comments can also have many VideoVotes (I realize this is confusing, so I should probably change it to Votes). (also, a video will have many comments.) How should I do this?
You first want to add voteable_id:integer and voteable_type:string to your video_votes table.
Then your models will look like:
class VideoVote < ActiveRecord::Base
belongs_to :voteable, :polymorphic => true
end
class Comment < ActiveRecord::Base
has_many :video_votes, :as => :voteable
#code
end
class Video < ActiveRecord::Base
has_many :video_votes, :as => :voteable
#code
end
Then you can access them just like any other has_many:
#video.video_votes
#comment.video_votes
#etc.