i need your help to link multiple records (here countries) with an other record (here policy) in same time into a form (new policy).
My models like :
class Retailer < ActiveRecord::Base
has_many :orders
has_many :policies, :dependent => :destroy
end
class Policy < ActiveRecord::Base
has_many :countries
end
class Country < ActiveRecord::Base
has_many :orders
has_many :users
has_one :platform
end
What i want is to link my new policy when i create this one in his form with multiple countries.
I want to use check boxes into this form to check what country i link (all countries stored in DB will be there).
I dont know if my association is appropriate for this context but i am bit lost how to do it.
Can someone help how to accomplish this and show me how my view should be ?
Thanks in advance.
What i want is to link my new policy when i create this one in his
form with multiple countries.
You want to set a belongs_to :country in your policy model instead of has_many :countries
class Policy < ActiveRecord::Base
belongs_to :country
end
and has_many :policies in your country model
class Country < ActiveRecord::Base
has_many :orders
has_many :users
has_one :platform
has_many :policies
end
I want to use check boxes into this form to check what country i link
(all countries stored in DB will be there).
For this,you can use collection_check_boxes.By setting like above(belongs_to :country),you will get country_id which you will be using with collection_check_boxes to check/uncheck the multiple countries.
Hope it helps!
Update
Might i have just wrong with the associations.In your case,it is a has_and_belongs_to_many.
class Policy < ActiveRecord::Base
has_and_belongs_to :countries
end
class Country < ActiveRecord::Base
has_many :orders
has_many :users
has_one :platform
has_and_belongs_to_many :policies
end
Related
I would like to achieve something as follows where PersonSubject has many topics, but the choices of these topics are limited to the the selection of topics through another model (ie: through the associated subject):
class Topic < ApplicationRecord
belongs_to :subject
end
class Subject < ApplicationRecord
has_many :topics
end
class PersonSubject < ApplicationRecord
belongs_to :person
belongs_to :subject
has_many :topics # where the choices are limited to the subject.skills
end
I would then like if any person_subject.subject.topics are deleted (or association removed), it would automatically update the person_subject.topics to no longer "point" to the Topic(s) that were deleted.
Is this possible?
You can use a lambda to put arbitrary filters on an association. See What is the equivalent of the has_many 'conditions' option in Rails 4?
has_many :topics, -> { where(skill: subject.skills) }
I don't know that this is exact code will work without seeing your schema (what is the data type of subject.skills, and how do you join this with topic?). But hopefully this gets you on the right track
edit
in response to your comment, I think
has_many :topics, through: :skills
would work
I'm trying to model my database in Ruby and can't figure out how to do it.
This is what I have so far:
class Course < ActiveRecord::Base
has_many :enrolled_ins
has_many :users, :through => :enrolled_ins
has_many :events, :dependent => :destroy
end
class User < ActiveRecord::Base
has_many :enrolled_ins
has_many :courses, :through => :enrolled_ins
end
class EnrolledIn < ActiveRecord::Base
belongs_to :users
belongs_to :courses
end
class Event < ActiveRecord::Base
belongs_to :courses
end
I want to add that when a user picks a course, they can select the different events that they want with that course, and those are assigned to them instead of them getting all the events.
I would add a UserEvents join. When you add a course, you would see a list of available events. Assuming you have a form with checkboxes, you would create the UserEvent records. I don't think you would need all 3 ID values (user, event, course). Course is just a way to group the various events.
class UserEvent < ActiveRecord::Base
belongs_to :user
belongs_to :event
end
I'd also add a dependent destroy on user and on event do destroy the join records if either side is removed.
I'm new to Rails and have some doubts about the kind of relationship do I need to use. Here is the case.
I have two models Offer and User, a user could belong to to many offers and offers can have many user. Also the users create the offers.
I think I have to use a has_many :through ralationship. For example I've created another model "Applicant". Applicant belongs_to user and belongs_to offer. But how is the relationship from the user and offer model? For example:
User Model
has_many :offer, :through => :applicant
Offer Model
has_many :user, :through => :applicant
My doubt is because I already have this two relationship
User Model
has_many :offers, :dependent => :destroy
Offer Model
belongs_to :user
After solve this, I guest I have to save the record in the applicant model from the applicanst_controller, right?
Thanks in advance
What you have described is a many-to-many relationship using a join table. You're actually pretty close but you just need to remove the has_many :offers, :dependent => :destroy from your user model and the blongs_to :user in your offer model. It should look something like this:
class User < ActiveRecord::Base
has_many :offers, :through => :applicants
end
class Applicant < ActiveRecord::Base
belongs_to :users
belongs_to :offers
end
class Offer < ActiveRecord::Base
has_many :users, :through => :applicants
end
You don't have to worry about the dependent destroy part as associations are automatically removed as the corresponding objects are removed. With a many to many association it doesn't really matter how you go about building the relationship. Either of the following will work:
#user.offers << #offer
#offers.users << #user
If you don't need to store any information specific to your applicant join table (e.g., time stamps, descriptions) you might instead want to look at a has_and_belongs_to_many relationship. Check out choosing between has_many_through and has_and_belongs_to_many for reference.
Edit
Heres the code for a HABTM relationship:
class User < ActiveRecord::Base
has_and_belongs_to_many :offers
end
class Offer < ActiveRecord::Base
has_and_belongs_to_many :users
end
Users on my site each have one list, which consists of a different type of users. I'm using a has_many through relationship to do this as follows:
List.rb:
class List < ActiveRecord::Base
belongs_to :company
has_many :list_applicants
has_many :applicants, through: :list_applicants
end
Applicant.rb:
class Applicant < ActiveRecord::Base
has_many :list_applicants
has_many :lists, through: :list_applicants
end
ListApplicant.rb
class ListApplicant < ActiveRecord::Base
attr_accessible :applicant_id, :list_id
belongs_to :applicant
belongs_to :list
end
Company.rb:
class Company < ActiveRecord::Base
has_one :list
end
When a user adds another user to their list, I'd like to record the date the user is added so they can sort their list of users by date added. What is the best way to do this?
You can use the created_at field of the ListApplicant model if it has one. If not, you may add manually a similar field.
UPDATE:
You can access the field by specifying both applicant and list like this:
#applicant.list_applicants.where(list_id: #list.id).first.created_at
I have a User model
class User < ActiveRecord::Base
has_many :projects
end
and I have a Project model
class Project < ActiveRecord::Base
belongs_to :user
end
Obviously right now each project is owned by a user and there can only be one user per project. I now want to make my models represent another relation between the two models. I want a User to be able to follow multiple Projects, no matter who owns the Project. I know that I am going to have to use a has_many :through and create a join, but I cant wrap my head around how to change the model to keep my current relationship and add the new relationship.
Well, in that case, in your show/index action display all the projects (Project.all) in your project table. This way all users have access to all the projects. Now, in your edit action, use user.projects.all to display projects of that particular user. That should solve your problem, I don't see the need of any further association here.
Update:
This should suffice:
class Project < ActiveRecord::Base
belongs_to :user
class User < ActiveRecord::Base
has_many :projects_followed, :through => :projects
user has_many :projects_owned, :through => :projects
If you don't wish to create two more relations, create just one:class ProjectsSubscribed
belongs_to :project with three fields: project_id, is_owned, is_followed
Try following relation.
class User < ActiveRecord::Base
has_many :followers
has_many :projects, :through => :followers
end
class Follower < ActiveRecord::Base
belongs_to :user
belongs_to :project
end
class Project < ActiveRecord::Base
has_many :followers
has_many :users, :through => :followers
end
Note it:
You can use has_many :through relationship if you need to work with the relationship model as an independent entity. If you don’t need to do anything with the relationship model, it may be simpler to set up a has_and_belongs_to_many relationship.
Hope it is helpful.