similar to: How to save has_one belongs_to models?

With a has_one/belongs_to relationship, what''s the best way to guarantee that the belongs_to object gets created and is accessible alongside the has_one object? I *think* the after_create callback is a good choice, but I discovered an oddity while trying it. F''rinstance, if every horse has a carriage: ============ ActiveRecord::Schema.define do create_table(:horses) {|t|

Hi. My model data is the following: - Place - User - Checkin Instead of having a Checkin that belongs to both User and Place, I chose to add another model, Program, that allows to list all the places a user can checkin into, and also hide the checkins he''s no longer involved in (= the user sign out of a specific program). That give me crazy relationships: Program has_many Checkin

There really doesn''t seem to be a *declarative* way to define a default value for belongs_to and has_one associations class Person < ActiveRecord::Base belongs_to :address end p = Person.new p.address.city = ''Atlantis'' # Bummer! Of course, there''s an easy way to avoid this class Person < ActiveRecord::Base belongs_to :address

So, I have 2 models A and B that share 5 common attributes and all other attributes are different. So I wanted to extract these 5 out into one common table and use has_one, belongs_to to knit it back together. So now there are 3 tables with 1 having the shared properties, we''ll call this table C. Table A id dollar_amount Table B id quantity_on_hand Table C id version My question is,

Hi All, Probably this has been asked numerous times, I apologize already! Can somebody point me to a good tutorial on how Rails works with relations? I know about database design and normalization, I also know about programming in general (and OOP for that matter). Only thing I can say is that I''m following the "Four days on Rails" tutorial by John McCreesh. He writes

Hello all, I have a syntax question. How does one refer to a field brought in via a has_one/belongs_to relationship in a form helper? Basically, I have two models: class Resource < ActiveRecord::Base has_one :other_thing end class OtherThing < ActiveRecord::Base belongs_to :resource end It has the normal id-resource_id foreign key relationship. OtherThing has two fields, plus the

The setup: class Location::Base < ActiveRecord::Base set_table_name :locations ... end class Location::Address < Location::Base ... end class Location::Airport < Location::Base ... end class Person < ActiveRecord::Base belongs_to :location, :polymorphic => true, :class_name => "Location::Base" ... end I want a unidirectional belongs_to relationship. That

Hi, I am very confused about an aspect of has_one and has_many relations, with regard to using the build method, and saving the belongs_to side. It''s a somewhat long post. so please bear with me :) First let''s consider the has_one scenario. Let''s say I have a student who must own exactly one car: class Student has_one(:car) end class Car belongs_to(:student)

I have a question about regarding the use of ''has_one'' in this scenario: Schema: User ---- id first_name last_name UserMessage ---- user_id message_id Message ---- id Assuming business rules dictate that a Message can have at most ONE User (let''s assume a message can be created without a user associated to it), these are my questions: 1) How would I use has_one

I''m new to ruby and rails and as a result am a bit lost on implementing a one to many relationship. In my DB I have 2 tables contents and locations, contents contains the foreign key location_id. I generated a content and a location model using rails scripts and then edited the models as follows class Content < ActiveRecord::Base has_one :location end class Location <

I have two models (Car and Driver) and a combobox to select which driver belongs to which car. I want the combobox just show the objects that have not yet been associated. # vehicle belongs_to: driver # driver has_one: vehicle # simple_form # vehicle/_form.html.haml = f.association: driver, label_method: :name, value_method: :id How to ensure validation before saving, to avoid problems of

I have two models called entity and user. The entities table has a column called users_id that contains the user id of the user that created the entity. In entity I have... has_one :user ... as I want to be able to show the user who created the entity from the entity object. But this produces the following error... Mysql::Error: #42S22Unknown column ''users.entity_id'' in

I know you get a lot of questions like this, but I couldn''t find one which answers exactly what I''m after. I''m reasonably new to rails, and I''m having a bit of trouble with when to use belongs_to. On the rails wiki ( http://wiki.rubyonrails.org/rails/pages/belongs_to), it says "In general, the Foo model belongs_to :bar if the foo table has a bar_id foreign

I''ve been using this sort helper to have sortable tables. http://wiki.rubyonrails.com/rails/pages/Sort+Helper I''ve encountered a situation where I need to sort a column that is not part of a table, but it''s related table. For example, say I have db tables called foos and bars. Foos have fields called name and title. And bars have fields called note and foo_id. Foos

I''m trying to build a system for generically storing an object graph, on top of AR itself. The idea is to define one base class, and use AR''s automatic single table inheritance to have it create the right class. Here''s what I have so far: table generic_objects: id int(11) not null auto_increment primary key type varchar(255) table generic_fields: id

Let me preface by saying i''m a total noob at ruby/rails. :-) For some reason, I am just not grasping the concept of has_one & belongs_to... I''m working on a project that includes user authentication, and 3 different types of user profiles. User profiles are either "fan", "band", or "venue" objects, and user logins are "user"

Suppose I have one table: states id statename And I have two other tables that contains states: houses id color state_id places id place_name state_id How would my model relationships look like? class State < ActiveRecord::Base belongs_to house belongs_to place end class House < ActiveRecord::Base has_one state end class Place <

I am having a problem with using SIngle Table Inheritance with a has_one relationship, and I am at a loss of what could be causing it. Below is the related code and the error message. class User < ActiveRecord::Base has_one :wishlist end class List < ActiveRecord::Base belongs_to :user end class Wishlist < List has_and_belongs_to_many :items, :class_name =>

Heya everyone! I am quite new to Rails and I am reading AWDwR. I am at Task E "Check Out!". I understand it quite well, but I have a problem with the last playground exercise: Add a Table which contains the payment types. All goes well, but I am not sure whether I should use has_many or has_one(as in the Playground wiki at http://wiki.pragprog.com/cgi-bin/wiki.cgi/PT-E-3). I use the

I''m having a difficult time wrapping my head around a set of models and their associations and seeing how they map into Rails. I''ll try to lay out my problem using the has_many and belongs_to structures. I have a RuleSpace, a Rule, and a Subject. A RuleSpace has_many Rules A RulesSpace has_many Subjects through Rules A Rule belongs_to (many) RuleSpaces A Rule has_many