model-associations

I'm trying sails.js association using one way reference (according to sails.js in action book). Now, the value of owner is successfully inserted in owner column, but value in cars column is not inserted. When I tried console.log(foundDriver) and console.dir(foundDriver) , it showed following things: { id: 1, Name: 'asdf' } { cars: [Getter/Setter], id: 1, Name: 'asdf' } My tables (1: driver , 2: car ): CODE: Car.js module.exports = { connection: 'mysqlAdapter', tableName: 'car', attributes: { id: { type: 'integer', primaryKey: true }, Name: { type: 'string' }, Brand: { type: 'string' }, Model:

I have 2 models - Teacher and Subject . A want to connect them via Join table with name Qualification . It looks like i do something wrong: class Teacher < ActiveRecord::Base has_and_belongs_to_many :subjects, :join_table => "Qualification" end class Subject < ActiveRecord::Base has_and_belongs_to_many :teachers, :join_table => "Qualification" end My migration: class CreateQualificationJoinTable < ActiveRecord::Migration def change create_table :qualification, :id => false do |t| t.integer :subject_id t.integer :teacher_id end add_index :qualification, :subject_id add_index :qualification,

I'm trying to design UML Analysis Class Diagram for a college project. My UML Diagram looks like this: I have encountered two different problems: User can have multiple roles. A user with Manager role can manage other users and their roles. How to illustrate this association in UML? User uses SwipeCard to access a room. How to show this association in UML? You have a really good start to an analysis model. Some things I would do: Reify the association between User and Role (or make it an association class) called Role Assignment . Add a verb-phrased property name to every end of every

For performance reason, I use as often as possible the only() keyword when writing up a mongoid query in order to specify the fields I want to load. The usual suspect, is for instance when I want a user's email of all my admins only for display purposes. I would write: User.where(:groups => :admins).only(:email).each do |u| puts u.email end I do this because my user model are quite full of a lot of data that I can gladly ignore when listing a bunch of emails. However, now let imagine, that my users are referenced via a Project model, so that for each project I can do: project.user . Thanks to

If I have a 'belongs_to' association in a model, I'd like to know the notional difference between validating an association: class Topping < ActiveRecord::Base belongs_to :pancake validates :pancake, presence: true ... and validating the associated model id: class Topping < ActiveRecord::Base belongs_to :pancake validates :pancake_id, presence: true ... Motivation: Some code which assigned a topping to a pancake stopped working at some time in the past. Changing the validation from association to id 'fixed' the problem, but I'd like to know the deeper reason why. (FYI, when stepping into the

I am porting a Rails app to Rails 4.2. This Rails app contains some rather complex manual SQL code in associations - partly due to DB optimizations (e.g. subselects instead of JOINs), partly due to no feasible alternative at the time of writing (Rails 3.0), partly surely due to lack of knowledge (I hope, at least - that would be easy to solve). Example: An InternalMessage class. Messages can be sent between users (Recipients of an InternalMessage, and 'deletions' of messages, are stored in InternalMessagesRecipients, since there can be several) and they can be read, replied to, forwarded and

I have been (hours) trouble with associations in Rails. I found a lot of similar problems, but I couldn't apply for my case: City's class: class City < ApplicationRecord has_many :users end User's class: class User < ApplicationRecord belongs_to :city validates :name, presence: true, length: { maximum: 80 } validates :city_id, presence: true end Users Controller: def create Rails.logger.debug user_params.inspect @user = User.new(user_params) if @user.save! flash[:success] = "Works!" redirect_to '/index' else render 'new' end end def user_params params.require(:user).permit(:name, :citys_id)