I am using ruby on rails 3.1 and have 2 models, an event and a group. Each event has_many groups, but has to have at least one "master" group, where the column :is_master => true
Class Group < ActiveRecord::Base
has_many :users
belongs_to :event
scope :master, where (:is_master => true)
end
Class Event< ActiveRecord::Base
has_many :groups
def master_group
groups.master
end
end
I want to be able to default all properties of the master group to the event, so for example, event.users.count should be the same as event.master_group.users.count.
Is there any way to do something like this? Can I do a has_many :through => master_group? Am I approaching this the wrong way?
Thanks!
I think what I was looking for was delegate
delegate :users, :to => :master_group
hope this helps someone...
Related
I have two classes (Game and Report) and want to link them with an additional attribute (default = yes or no).
The game should then have default_reports and optional_reports.
The association is then updated by selecting the default and optional reports in a select (multiple) in the games create/edit form.
I have tried using has_many and through as well as polymorphic associations, but nothing seems to fit the use case, where the associated objects are fixed and you only want to manage associations.
class Game < ActiveRecord::Base
has_many :game_reports
has_many :reports, :through => :game_reports
end
class Report < ActiveRecord::Base
has_many :game_reports
has_many :games, :through => :game_reports
end
class GameReport < ActiveRecord::Base
belongs_to :game
belongs_to :report
end
Any help is appreciated!
Thanks
this is just the model. the view and form to create the records is an entirely different matter.
you can always add a conditions option to has_many. I'm assuming you're going to add default to game_reports so change your class to something like.
class Game < ActiveRecord::Base
has_many :game_reports
has_many :reports, :through => :game_reports
has_many :default_reports, through: :game_reports, source: :report, conditions: { game_reports: { default: true } }
end
Rails 4.2+, use a Polymorphic association with scope and specify the foreign_key and foreign_type options.
class GameReport
belongs_to :report, :polymorphic => true
end
class Game
has_many :game_reports, :as => :report, :dependent => :destroy
has_many :reports, -> { where attachable_type: "GameReport"},
class_name: GameReport, foreign_key: :game_report_id,
foreign_type: :game_report_type, dependent: :destroy
end
Other approachs:
Rails Polymorphic Association with multiple associations on the same model
I have the following (on RoR 3.1 and MySQL 5.1):
class Menu < ActiveRecord::Base
has_many :menu_headers
has_many :menu_items, :through => :menu_headers
belongs_to :location
end
class MenuHeader < ActiveRecord::Base
acts_as_tree :parent_id
has_many :menu_items
belongs_to :menu
end
class MenuItem < ActiveRecord::Base
scope :is_enabled, where(:is_enabled => true)
belongs_to :menu_header
end
I'd like to be able to call the scope across the relationship; something like this:
# call the scope :is_enabled here
Menu.find(12).(where menu_items.is_enabled)
but not sure how to do this.
I'd like the behavior for:
Menu.find(12)
to continue to pull menu_items where is_enabled=false
Any ideas on how to do this?
thx
edit #1
added the act_as_tree and location associations as these also need to be working.
Something like this Scope with join on :has_many :through association might work but seems a little bit ugly
This should do the trick:
Menu.find(12).menu_items.is_enabled
It will return all enabled menuitem associated with the menu with id 12.
So if I have the following relationship
class Item < ActiveRecord::Base
has_many :item_user_relationships
has_many :users, :through => :item_user_relationships
end
class User < ActiveRecord::Base
has_many :item_user_relationships
has_many :items, :through => :item_user_relationships
end
class ItemUserRelationship < ActiveRecord::Base
belongs_to :item
belongs_to :user
attr_accessible :role
end
What's the rails way to include the role attribute when listing all the Users of an Item?
#users = #item.users # I want to include the role as part of a user
Thanks!
UPDATE: I'm still having trouble with this. My goal is to get an array of User models that have their role included in the attributes.
I'm note sure if I understand you correctly, but maybe this is what you want?
#users = #item.users
#users.each do |user|
puts user.item_user_relationships.first.role
end
With the following Rails models:
class Group < ActiveRecord::Base
has_many :group_locations, :dependent => :restrict
has_many :locations, :through => :group_locations, :dependent => :restrict
end
class Location < ActiveRecord::Base
has_many :group_locations, :dependent => :destroy
has_many :groups, :through => :group_locations
end
class GroupLocation < ActiveRecord::Base
belongs_to :group
belongs_to :location
end
I am trying to Find all of the locations that are associated with at least one of several groups contained in the string "group_list" (e.g. "1,2,3,4,5"). If it was a field from the Location record, I would specify a condition of "*field in (#{group_list})*". But how do I accomplish my goal when I want to have at least one of the location's "group_location" whose "group_id" is in the list (or, alternatively, one "group" whose group_id is in the list).
I know how to do it with pure SQL, but how do you do it with Rails?
#taro You are right. Started by adding the code
joins(:group_locations).where("group_id in (?)", group_id_array)
Then I proceeded to define a scope just to make it a nice package:
scope :locations_in_groups, lambda { |grparray| joins(:group_locations).where("group_id in (?)", grparray) }
Thanks for your help.
I have a User class with
class User < ActiveRecord::Base
has_many :forum_subscriptions
has_many :forums, :through => :forum_subscriptions
And a Forum class with
class Forum < ActiveRecord::Base
has_many :users
I want to find all the users that are subscribed to forum "sport", forum "TV" and forum "Hobby"
What is the most elegant way to do it?
(I have a lot of ugly stuff in my mind :-)
Here is something I would use:
User.joins(:forums).where("forums.title IN (?)", %w(sport TV Hobby)).group("users.id")
I assumed the column for the forum's title is 'title'. Change it when you're using some other name. You can put this inside a nice scope inside the User Model to make it a bit more dynamic.
scope :subscribed_to, lambda { |forum_titles| joins(:forums).where("forums.title IN (?)", forum_titles).group("users.id") }
Now you can call this scope from inside the Controller or some other place:
User.subscribed_to(%w(sport TV Hobby)) # => Get all users that are subscribed to sport, TV and Hobby
User.subscribed_to(["sport", "TV", "Hobby"]) # => Does the same
User.subscribed_to(%w(Hobby)) # => Get all users that are subscribed to Hobby
User.subscribed_to("Hobby") # => Does the same
I assumed you have the following relationships:
class User < ActiveRecord::Base
has_many :forum_subscriptions
has_many :forums, :through => :forum_subscriptions
end
class Forum < ActiveRecord::Base
has_many :forum_subscriptions
has_many :users, :through => :forum_subscriptions
end
class ForumSubscription < ActiveRecord::Base
belongs_to :user
belongs_to :forum
end
Hope this is what you needed. :)