similar to: Using :include with has_one vs. has_many

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

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

People, In the cookbook eg, categories has_many recipes but in a book eg, book has_one description - doesn''t that mean that the id of the description should be the same as the id of the book (instead of having it''s own "description_id" in the book table? Thanks, Phil. -- Philip Rhoades Pricom Pty Limited (ACN 003 252 275 ABN 91 003 252 275) GPO Box 3411 Sydney

Hi, How do I associate two different tables which have a lookup id (table) as common. I tried the has_many :table2, :through => look_up_table in my table1 model. Any hints? Thanks, Hari -- Posted via http://www.ruby-forum.com/.

I have users who belong to a group. I also have a room that belongs to a group. I want to use a has_many through association to link the room and the users as such: class Room < ActiveRecord::Base belongs_to :group has_many :users, :through => :group end The SQL generated for the search is incorrect: SELECT users.* FROM users INNER JOIN group ON users.group_id = groups.id WHERE

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

Acts as automatic has two purposes: 1) provide acts_as_automatic act, which will automatically run the appropriate methods when conventions are adhered to (e.g. if you have category_id, it will assume that the model belongs_to :category). Only belongs_to via something_id is currently implemented. 2) Allow the creation of associations.yml, which will hold associations instead of inside each

This is a bit of a long question, but to those of you with some experience, it should be fairly simple I think. I have a notes page that should list all notes the user has entered for all books chronologically like this. Book One: This is the note. Book Four: This is the note. Book One: A different note, entered later. Right now my models are: User has_many :books Book has_many

Hi, seem to keep running into a wall here. I can''t find any resources on site navigation that can deal with any model being in the nav, allow nesting, and can dynamically update. So I thought about it for a while, and decided on a MenuItems class, which contained the position of the child in relation to it''s siblings, where the parent and the child were polymorphic. Then a given

It seems that using a join model that joins with two has_many''s will fail to generate proper SQL class StudentSemesterRecord < ActiveRecord::Base belongs_to :semester has_many :discipline_records, :through => :semester end class Semester < ActiveRecord::Base has_many :student_semester_records has_many :discipline_records end class DisciplineRecord <

Dear Railers, I am toying with a new project and have a schema design question. I have a tree-like node structure. Each of the nodes will be associated with a single object. This associated object can be of a variety of types. I represent the tree through a Node class which acts_as_tree. Now imagine three other classes--Animals, Fruits and Vegetables. Each node will have an association

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

1. A category has parent categories. 2. A product is in many categories and a category has many products. 3. Products and category both have images in the same image table. ie. a product and / or category could have multiple images.<=== my question is related to this So among other things I presume I have to do the following: class Category < ActiveRecord:Base #...

I''ve got an order model that stores order data. One piece of data is a credit card type, which is a digit 1,2 or 3. I have a cardType model that has an id, shortName and LongName for the credit card merchant (visa, mastercard, amex). I want to be able to say: order.cardType.shortName, but can''t seem to get has_one working. It works with has_many and a finder_sql statement on

I have this code that is using svn externals with rails EDGE working fine for the past couple of months. A couple of days ago, this code died. Even after deleting vendor/rails, this code doesnt work: class Tag < ActiveRecord::Base has_many :taggings has_many :events, :through => :taggings has_many :users, :through => :taggings end class User < ActiveRecord::Base # Virtual

If the associated object of a has_one association has been loaded, it is resaved when the parent is saved. Eg: class Person < ActiveRecord::Base has_one :user end class User < ActiveRecord::Base belongs_to :person end p = Person.find(:first) p.save # As expected, nothing happens with the user association p.user # Loads the associated object p.save # As well as saving the person, the

I have following tables with following models: users(id, role_id) *has_many :entries* categories(id, category_name) *has_many :entries* entries(id, category_id, user_id) *belongs_to :user, belongs_to :category, has_one :storage* storages(id, title, content, entry_id)* belongs_to :entry*, *has_one :vote* votes(id, count, storage_id) *belongs_to :storage* Now,

Hi all. Got a stupid-simple question about associations. I have two models - school and course. There are a fixed number of schools (set up in the migration). Each course is assigned a school and a school will be associated with multiple courses... How do I set up the associations? Do (can) I have School :has_one :course and Course :has_many :schools? Does the schools table then get a course_id

Hi I have a has_many :through. It''s a basic mapping of Project id .... User id .... TeamMembers project_id user_id role What I would like to do is have different roles so I can have in the project model has_many :core_members, :through => :team_members, :source => :user but I would like to limit this to only those with the "core" role in the team members table for

Hi, Why is it that polymorphic associations only work with the :has_many and :belongs_to relationships? Why can''t it be a :has_one? Matt