So, I've read in some book about tip "Use model association", which encourages developers to use build methods instead of putting ids via setters.
Assume you have multiple has_many relationships in your model. What's best practise for creating model then ?
For example, let's say you have models Article, User and Group.
class Article < ActiveRecord::Base
belongs_to :user
belongs_to :subdomain
end
class User < ActiveRecord::Base
has_many :articles
end
class Subdomain < ActiveRecord::Base
has_many :articles
end
and ArticlesController:
class ArticlesController < ApplicationController
def create
# let's say we have methods current_user which returns current user and current_subdomain which gets current subdomain
# so, what I need here is a way to set subdomain_id to current_subdomain.id and user_id to current_user.id
#article = current_user.articles.build(params[:article])
#article.subdomain_id = current_subdomain.id
# or Dogbert's suggestion
#article.subdomain = current_subdomain
#article.save
end
end
Is there a cleaner way ?
Thanks!
This should be a little cleaner.
#article.subdomain = current_subdomain
The only thing I can think of is merging the subdomain with params:
#article = current_user.articles.build(params[:article].merge(:subdomain => current_subdomain))
Related
newbie here...
I am trying to create an events registration page where anybody can register for an event without logging into the system.
My problem is trying to figure out how to tie the registration info to the specific event. I've created all the associations but can't figure how to tell the db that the person is registering for a specific event.
Here are my associations:
class Event < ActiveRecord::Base
belongs_to :user
has_many :event_regs
has_many :regs, through: :event_regs
class Reg < ActiveRecord::Base
has_many :event_regs
class Reg < ActiveRecord::Base
has_many :event_regs
Thanks in advance
Newbie here
Welcome!
Here's what you'll need:
#app/models/event.rb
class Event < ActiveRecord::Base
has_many :registrations
end
#app/models/registration.rb
class Registration < ActiveRecord::Base
belongs_to :event
end
This will allow you to use the following:
#config/routes.rb
resources :events do #-> url.com/events/:id
resources :registrations #-> url.com/events/:event_id/registrations/
end
#app/controllers/registrations_controller.rb
class RegistrationsController < ApplicationController
def new
#event = Event.find params[:event_id]
#registration = #event.registration.new
end
def create
#event = Event.find params[:event_id]
#registration = #event.registration.new registration_params
end
private
def registration_params
params.require(:registration).permit(:all, :your, :params)
end
end
This will create a new registration record in your db, associating it with the Event record you've accessed through the route.
--
From this setup, you'll be able to use the following:
#app/controllers/events_controller.rb
class EventsController < ApplicationController
def show
#event = Event.find params[:id]
end
end
#app/views/events/show.html.erb
<% #event.registrations.each do |registration| %>
# -> output registration object here
<% end %>
Foreign Keys
In order to understand how this works, you'll be best looking at something called foreign keys...
This is a relational database principle which allows you to associate two or more records in different database tables.
Since Rails is designed to work with relational databases, each association you use will require the use of a "foreign key" in some respect.
In your case, I would recommend using a has_many/belongs_to relationship:
You'll need to make sure you add the event_id column to your registrations database.
I'm new to rails. I want to create simple url for the users, I don't want to use friendly_id, if possible. I can already change the url using this
#MyModel.rb
def to_param
address
end
#MyController.rb
#user = Admin::Account.find_by_address(params[:id])
but what I really want is to use name instead of address, but the problem is that, name does not belong to MyModel.rb it balongs to OtherModel.rb, is this even pissible? please help
here is a sample of what I want
#MyModel.rb
def to_param
name #name is a data/column from OtherModel.rb
end
#MyController.rb
#user = Admin::Account.find_by_name(params[:id])
#instead of using find_by_address I can now use find_by_name
here is a sample of my model relations
class Admin::MyModel < ActiveRecord::Base
has_many :other_model, :class_name => 'Admin::OtherModel', dependent: :destroy
end
class Admin::OtherModel < ActiveRecord::Base
belongs_to :my_model, :class_name => 'Admin::MyModel'
end
In Ruby on Rails I have a user models and a jobs model joined through a different model called applicants. I have a button for the users when they want to "remove their application for this job" but I don't know how to remove the specific user, and for that matter I don't know if I'm doing a good job at adding them either (I know atleast it works).
user.rb
class User < ActiveRecord::Base
...
has_many :applicants
has_many:jobs, through: :applicants
end
job.rb
class Job < ActiveRecord::Base
...
has_many :applicants
has_many:users, through: :applicants
end
applicant.rb
class Applicant < ActiveRecord::Base
belongs_to :job
belongs_to :user
end
when someone applies for a job my jobs controller is called:
class JobsController < ApplicationController
...
def addapply
#job = Job.find(params[:id])
applicant = Applicant.find_or_initialize_by(job_id: #job.id)
applicant.update(user_id: current_user.id)
redirect_to #job
end
...
end
Does that .update indicate that whatever is there will be replaced? I'm not sure if I'm doing that right.
When someone wants to remove their application I want it to go to my jobs controller again but I'm not sure what def to make, maybe something like this?
def removeapply
#job = Job.find(params[:id])
applicant = Applicant.find_or_initialize_by(job_id: #job.id)
applicant.update(user_id: current_user.id).destroy
redirect_to #job
end
does it ave to sort through the list of user_ids save them all to an array but the one I want to remove, delete the table then put them all back in? I'm unsure how this has_many works, let alone has_many :through sorry for the ignorance!
thanks!
Let's assume the user will want to remove their own application. You can do something like this:
class UsersController < ApplicationController
def show
#applicants = current_user.applicants # or #user.find(params[:id]), whatever you prefer
end
end
class ApplicantsController < ApplicationController
def destroy
current_user.applications.find(params[:id]).destroy
redirect_to :back # or whereever
end
end
And in your view:
- #applicants.each do |applicant|
= form_for applicant, method: :delete do |f|
= f.submit
Don't forget to set a route:
resources :applicants, only: :destroy
Some observations, I would probably name the association application instead of applicant. So has_many :applications, class_name: 'Applicant'.
In Rails 3.2 I have been looking for a way to traverse the associations of an object within the before_add callback.
So basically my use case is:
class User < ActiveRecord::Base
has_and_belongs_to_many :meetings
end
class Meeting < ActiveRecord::Base
has_and_belongs_to_many :users
has_many :comments, :before_add => :set_owner_id
end
class Comment < ActiveRecord::Base
belongs_to :meeting
end
def set_owner_id(child)
child.owner_id = <<<THE USER ID for #user >>>
end
and I am creating a comment within the context of a user:
#user.meetings.first.comments.create
How do I traverse the associations from within the before_add callback to discover the id of #user? I want to set this at model level. I have been looking at proxy_association, but I may be missing something. Any ideas?
You should probably create the comment in the context of the meeting, no? Either way, you should handle this in the controller since you'll have no access to #user in your model.
#comment = Meeting.find(id).comments.create(owner_id: #user, ... )
But if you insist on your way, do this:
#comment = #user.meetings.first.comments.create(owner_id: #user.id)
Below I have outlined the structure of a polymorphic association.
In VacationsController I put some comments inline describing my current issue. However, I wanted to post this to see if my whole approach here is a little off. You can see in business_vacations_controller and staff_vacations_controller that I've had to make 'getters' for the model and controller so that I can access them from within vacations_model so I know which type of object I'm dealing with. Although it works, it's starting to feel a little questionable.
Is there a better 'best practice' for what I'm trying to accomplish?
models
vacation.rb
class Vacation < ActiveRecord::Base
belongs_to :vacationable, :polymorphic => true
end
business.rb
class Business < ActiveRecord::Base
has_many :vacations, :as => :vacationable
end
staff.rb
class Staff < ActiveRecord::Base
has_many :vacations, :as => :vacationable
end
business_vacation.rb
class BusinessVacation < Vacation
end
staff_vacation.rb
class StaffVacation < Vacation
end
controllers
business_vacations_controller.rb
class BusinessVacationsController < VacationsController
private
def controller_str
"business_schedules"
end
def my_model
BusinessVacation
end
def my_model_str
"business_vacation"
end
end
staff_vacations_controller.rb
class StaffVacationsController < VacationsController
private
def controller_str
"staff_schedules"
end
def my_model
StaffVacation
end
def my_model_str
"staff_vacation"
end
end
vacations_controller.rb
class VacationsController < ApplicationController
def create
# Build the vacation object with either an instance of BusinessVacation or StaffVacation
vacation = #class.new(params[my_model_str])
# Now here's the current issue -- I want to save the object on the association. So if it's a 'BusinessVacation' object I want to save something like:
business = Business.find(vacation.vacationable_id)
business.vacations.build
business.save
# But if it's a 'StaffVacation' object I want to save something like:
staff = Staff.find(vacation.vacationable_id)
staff.vacations.build
staff.save
# I could do an 'if' statement, but I don't really like that idea. Is there a better way?
respond_to do |format|
format.html { redirect_to :controller => controller_str, :action => "index", :id => vacation.vacationable_id }
end
end
private
def select_class
#class = Kernel.const_get(params[:class])
end
end
It feels like a lot of hoops to jump through in the VacationsController to make it aware of the context. Is there a reason that the StaffVacationsController and BusinessVacationsController couldn't each have a #create action and the views would submit to whichever is appropriate? These actions would already know the model context and be able to redirect to the appropriate url afterward.