I have a polymorphic model; result, with belongs_to result_table, polymorphic: true which i'm using with two other models; team and sport, through a one to one relationship and its working. Due to the one to one relationship, i have a callback function,after_create :build_result_table which i use in setting and saving the result_table_id and result_table_type in the result table in the database. The issue I have is the input saved in result_table_type, its VARCHAR, but it seems to be saving the input as an integer
def build_result_table
Result.create(result_table_id: self.id, result_table_type: self)
end
I think the issue is probably with result_table_type: self, but i tried result_table_type: self.class.name to save the name of the class but it threw an error. Any advice on saving a unique value in the result_table_type column..
EDIT
I'm adding the models involved, though i have done the saving manually as said by #Mohammad in the comments, but will also be grateful, if i can be shown how i can ask rails to save the values automatically.
APP/MODEL/SPORT.RB
class Sport < ActiveRecord::Base
attr_accessible :sport_name, :sport_id, :result_attributes, :result_table_id
has_one :result, as: :result_table
after_create :build_result_table
accepts_nested_attributes_for :result
def build_result_table
Result.create(result_table_id: self.id, result_table_type: self.class.name)
end
end
APP/MODEL/TEAM.RB
class Team < ActiveRecord::Base
has_one :result, as: :result_table
attr_accessible :teamname, :color, :result_attributes
after_create :build_result_table
accepts_nested_attributes_for :result
def build_result_table
Result.create(result_table_id: self.id, result_table_type: self.class.name)
end
end
APP/MODEL/RESULT.RB
class Result < ActiveRecord::Base
attr_accessible :sport_id,:team_id, :result_table_id, :result_table_type
belongs_to :result_table, polymorphic: true
end
# Either one of these
Result.create(result_table: self)
Result.create(result_table_id: self.id, result_table_type: self.class.to_s)
Related
I want to change has_many association behaviour
considering this basic data model
class Skill < ActiveRecord::Base
has_many :users, through: :skills_users
has_many :skills_users
end
class User < ActiveRecord::Base
has_many :skills, through: :skills_users, validate: true
has_many :skills_users
end
class SkillsUser < ActiveRecord::Base
belongs_to :user
belongs_to :skill
validates :user, :skill, presence: true
end
For adding a new skill we can easily do that :
john = User.create(name: 'John Doe')
tidy = Skill.create(name: 'Tidy')
john.skills << tidy
but if you do this twice we obtain a duplicate skill for this user
An possibility to prevent that is to check before adding
john.skills << tidy unless john.skills.include?(tidy)
But this is quite mean...
We can as well change ActiveRecord::Associations::CollectionProxy#<< behaviour like
module InvalidModelIgnoredSilently
def <<(*records)
super(records.to_a.keep_if { |r| !!include?(r) })
end
end
ActiveRecord::Associations::CollectionProxy.send :prepend, InvalidModelIgnoredSilently
to force CollectionProxy to ignore transparently adding duplicate records.
But I'm not happy with that.
We can add a validation on extra validation on SkillsUser
class SkillsUser < ActiveRecord::Base
belongs_to :user
belongs_to :skill
validates :user, :skill, presence: true
validates :user, uniqueness: { scope: :skill }
end
but in this case adding twice will raise up ActiveRecord::RecordInvalid and again we have to check before adding
or make a uglier hack on CollectionProxy
module InvalidModelIgnoredSilently
def <<(*records)
super(valid_records(records))
end
private
def valid_records(records)
records.with_object([]).each do |record, _valid_records|
begin
proxy_association.dup.concat(record)
_valid_records << record
rescue ActiveRecord::RecordInvalid
end
end
end
end
ActiveRecord::Associations::CollectionProxy.send :prepend, InvalidModelIgnoredSilently
But I'm still not happy with that.
To me the ideal and maybe missing methods on CollectionProxy are :
john.skills.push(tidy)
=> false
and
john.skills.push!(tidy)
=> ActiveRecord::RecordInvalid
Any idea how I can do that nicely?
-- EDIT --
A way I found to avoid throwing Exception is throwing an Exception!
class User < ActiveRecord::Base
has_many :skills, through: :skills_users, before_add: :check_presence
has_many :skills_users
private
def check_presence(skill)
raise ActiveRecord::Rollback if skills.include?(skill)
end
end
Isn't based on validations, neither a generic solution, but can help...
Perhaps i'm not understanding the problem but here is what I'd do:
Add a constraint on the DB level to make sure the data is clean, no matter how things are implemented
Make sure that skill is not added multiple times (on the client)
Can you show me the migration that created your SkillsUser table.
the better if you show me the indexes of SkillsUser table that you have.
i usually use has_and_belongs_to_many instead of has_many - through.
try to add this migration
$ rails g migration add_id_to_skills_users id:primary_key
# change the has_many - through TO has_and_belongs_to_many
no need for validations if you have double index "skills_users".
hope it helps you.
I'm new to Rails and ActiveRecord and need some help. Basically, I have 4 models: User, Property, PropertyAccount, and AccountInvitation. Users and Properties have a many to many relationship via PropertyAccounts. AccountInvitations have a user's email and a property_id.
What I want to happen is that after a user registers on my app, his user account is automatically associated with some pre-created Properties. What I don't know how to do is write the query to get the Property objects from the AccountInvitations and save them to the User object. Please see def assign_properties for my pseudo code. Any help is welcome, thanks so much!
class User < ActiveRecord::Base
has_many :property_accounts
has_many :properties, through: :property_accounts
after_create :assign_properties
# Check to see if user has any pre-assigned properties, and if so assign them
def assign_properties
account_invitations = AccountInvitations.where(email: self.email)
if account_invitations.any?
account_invitations.each do |i|
properties += Property.find(i.property_id)
end
self.properties = properties
self.save
end
end
end
class AccountInvitation < ActiveRecord::Base
belongs_to :property
validates :property_id, presence: true
validates :email, uniqueness: {scope: :property_id}
end
class Property < ActiveRecord::Base
has_many :account_invitations
has_many :property_accounts
has_many :users, through: :property_accounts
end
class PropertyAccount < ActiveRecord::Base
belongs_to :property
belongs_to :user
end
Thanks to #wangthony , I looked at the includes method on http://apidock.com/rails/ActiveRecord/QueryMethods/includes and tweaked one of their examples in order to get this to work. Here's the solution:
def assign_property
self.properties = Property.includes(:account_invitations).where('account_invitations.email = ?', self.email).references(:account_invitations)
self.save
end
I believe you can do this:
user.properties = Property.includes(:account_invitations).where(email: user.email)
user.save
I read this interesting article about Using Polymorphism to Make a Better Activity Feed in Rails.
We end up with something like
class Activity < ActiveRecord::Base
belongs_to :subject, polymorphic: true
end
Now, if two of those subjects are for example:
class Event < ActiveRecord::Base
has_many :guests
after_create :create_activities
has_one :activity, as: :subject, dependent: :destroy
end
class Image < ActiveRecord::Base
has_many :tags
after_create :create_activities
has_one :activity, as: :subject, dependent: :destroy
end
With create_activities defined as
def create_activities
Activity.create(subject: self)
end
And with guests and tags defined as:
class Guest < ActiveRecord::Base
belongs_to :event
end
class Tag < ActiveRecord::Base
belongs_to :image
end
If we query the last 20 activities logged, we can do:
Activity.order(created_at: :desc).limit(20)
We have a first N+1 query issue that we can solve with:
Activity.includes(:subject).order(created_at: :desc).limit(20)
But then, when we call guests or tags, we have another N+1 query problem.
What's the proper way to solve that in order to be able to use pagination ?
Edit 2: I'm now using rails 4.2 and eager loading polymorphism is now a feature :)
Edit: This seemed to work in the console, but for some reason, my suggestion of use with the partials below still generates N+1 Query Stack warnings with the bullet gem. I need to investigate...
Ok, I found the solution ([edit] or did I ?), but it assumes that you know all subjects types.
class Activity < ActiveRecord::Base
belongs_to :subject, polymorphic: true
belongs_to :event, -> { includes(:activities).where(activities: { subject_type: 'Event' }) }, foreign_key: :subject_id
belongs_to :image, -> { includes(:activities).where(activities: { subject_type: 'Image' }) }, foreign_key: :subject_id
end
And now you can do
Activity.includes(:part, event: :guests, image: :tags).order(created_at: :desc).limit(10)
But for eager loading to work, you must use for example
activity.event.guests.first
and not
activity.part.guests.first
So you can probably define a method to use instead of subject
def eager_loaded_subject
public_send(subject.class.to_s.underscore)
end
So now you can have a view with
render partial: :subject, collection: activity
A partial with
# _activity.html.erb
render :partial => 'activities/' + activity.subject_type.underscore, object: activity.eager_loaded_subject
And two (dummy) partials
# _event.html.erb
<p><%= event.guests.map(&:name).join(', ') %></p>
# _image.html.erb
<p><%= image.tags.first.map(&:name).join(', ') %></p>
This will hopefully be fixed in rails 5.0. There is already an issue and a pull request for it.
https://github.com/rails/rails/pull/17479
https://github.com/rails/rails/issues/8005
I have forked rails and applied the patch to 4.2-stable and it works for me. Feel free to use my fork, even though I cannot guarantee to sync with upstream on a regular basis.
https://github.com/ttosch/rails/tree/4-2-stable
You can use ActiveRecord::Associations::Preloader to preload guests and tags linked, respectively, to each of the event and image objects that are associated as a subject with the collection of activities.
class ActivitiesController < ApplicationController
def index
activities = current_user.activities.page(:page)
#activities = Activities::PreloadForIndex.new(activities).run
end
end
class Activities::PreloadForIndex
def initialize(activities)
#activities = activities
end
def run
preload_for event(activities), subject: :guests
preload_for image(activities), subject: :tags
activities
end
private
def preload_for(activities, associations)
ActiveRecord::Associations::Preloader.new.preload(activities, associations)
end
def event(activities)
activities.select &:event?
end
def image(activities)
activities.select &:image?
end
end
image_activities = Activity.where(:subject_type => 'Image').includes(:subject => :tags).order(created_at: :desc).limit(20)
event_activities = Activity.where(:subject_type => 'Event').includes(:subject => :guests).order(created_at: :desc).limit(20)
activities = (image_activities + event_activities).sort_by(&:created_at).reverse.first(20)
I would suggest adding the polymorphic association to your Event and Guest models.
polymorphic doc
class Event < ActiveRecord::Base
has_many :guests
has_many :subjects
after_create :create_activities
end
class Image < ActiveRecord::Base
has_many :tags
has_many :subjects
after_create :create_activities
end
and then try doing
Activity.includes(:subject => [:event, :guest]).order(created_at: :desc).limit(20)
Does this generate a valid SQL query or does it fail because events can't be JOINed with tags and images can't be JOINed with guests?
class Activity < ActiveRecord::Base
self.per_page = 10
def self.feed
includes(subject: [:guests, :tags]).order(created_at: :desc)
end
end
# in the controller
Activity.feed.paginate(page: params[:page])
This would use will_paginate.
What i have created is a "active" field in my topics table which i can use to display the active topics, which will contain at first the time the topic was created and when someone comments it will use the comment.created_at time and put it in the active field in the topics table, like any other forum system.
I found i similar question here
How to order by the date of the last comment and sort by last created otherwise?
But it wont work for me, im not sure why it wouldn't. And i also don't understand if i need to use counter_cache in this case or not. Im using a polymorphic association for my comments, so therefore im not sure how i would use counter_cache. It works fine in my topic table to copy the created_at time to the active field. But it wont work when i create a comment.
Error:
NoMethodError in CommentsController#create
undefined method `topic' for
Topic.rb
class Topic < ActiveRecord::Base
attr_accessible :body, :forum_id, :title
before_create :init_sort_column
belongs_to :user
belongs_to :forum
validates :forum_id, :body, :title, presence: true
has_many :comments, :as => :commentable
default_scope order: 'topics.created_at DESC'
private
def init_sort_column
self.active = self.created_at || Time.now
end
end
Comment.rb
class Comment < ActiveRecord::Base
attr_accessible :body, :commentable_id, :commentable_type, :user_id
belongs_to :user
belongs_to :commentable, :polymorphic => true
before_create :update_parent_sort_column
private
def update_parent_sort_column
self.topic.active = self.created_at if self.topic
end
end
Didn't realise you were using a polymorphic association. Use the following:
def update_parent_sort_column
commentable.active = created_at if commentable.is_a?(Topic)
commentable.save!
end
Should do the trick.
I've got the following two classes
class Car < Vehicle
has_one :steering_wheel, as: :attached
end
class SteeringWheel < ActiveRecord::Base
belongs_to :attached
has_many :components
has_one :rim, class_name: 'Components', order: 'id DESC'
attr_accessible :components
end
class Component < ActiveRecord::Base
include SpecificationFileService::Client
attr_accessible :created_by
belongs_to :steering_wheel
end
Then in my specs:
context "given an attachment", :js do
before do
#car = create(:car, make: "honda")
#steering_wheel = SteeringWheel.create(attached: #car)
#steering_wheel.save
#car.save
#car.reload
end
specify "test the setup", :js do
puts #car.steering_wheel
end
end
Which prints: nil
A way that I have found fixes this is explicitly setting steering_wheel on car like so:
#car.steering_wheel = #steering_wheel
just before the save.
EDIT:
As suggested in the comments below, I have tried adding polymorphic: true, which did not resolve the issue. Also, I've fleshed out more of the SteeringWheel model above
My question is why, and how can I add this to the callback chain implicitly
Like #abraham-p mentioned in a comment, you need to declare the belongs_to relation as:
belongs_to :attached, polymorphic: true
Otherwise it will attempt to look for an Attached model, and be sure to include these fields in your SteeringWheel model:
attached_type
attached_id
The rest is worked out by Rails :)