similar to: Eager Loading: Stacking Includes?

I wonder if you can have more than one has_many :through association between 2 models. For example... I have a model Teacher and a model Class Now, 1 Teacher works in many Classes, right?. So I need a join model like class Work < ActiveRecord::Base belongs_to :teacher belongs_to :class end But I also would like to know if a teacher CAN teach a class before I

I am a bit confused about counter_cache here. The API docs http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html say that only the belongs_to association can take the :counter_cache option. When I try to use it on a has_many I get an "unknown key(s): counter_cache" error. Why would this be the case? belongs_to means that this model has a field with an id

Can someone please confirm or correct the following statements? If I have the following tables create table as (id int, [...], b_id int); create table bs (id int, [...], a_id int); create table as_bs (a_id int, b_id int); and the associations woould be defined like this class A << ... habtm :bs belongs_to :b end so my Model A has a habtm collection of Bs *plus* a direct

Hi there, I''ve been working on this for awhile and have finally decided to ask for a little guidance.I have a slight problem trying to save a selection. I have two models: A "Posting" has_many "Categories", and a "Category" belongs_to one "Posting". With that said, in the posting model I have "has_many :categories" and within the

In a belongs_to association, is there a way to tell if the associated object was newly created? Hopefully this will explain my question: A Firm class declares has_many<http://api.rubyonrails.com/classes/ActiveRecord/Associations/ClassMethods.html#M000530>:clients and a client class declares

Here''s the problem I have the following models User - is a person Team - is a team Wherenote - snipet of info about a user''s whereabouts on a certain day Team has_and_belongs_to_many :users User has_and_belongs_to_many :teams has_many :wherenotes Wherenote belongs_to :user each Wherenote has a note_date On one page I want to pull back all the Users from a particular Team

Here''s the setup (working off Rails 1.1.4): Class Project belongs_to :employee Class Employee < Person has_many :projects When I try to paginate(:employees, :include => :projects) I get the error "Association named ''projects'' was not found; perhaps you misspelled it?" I can :include other models that the Person class has_many or habtm of, and if I

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

I have the following models: class Resume belongs_to :resume_assignments end class User belongs_to :resume_assignments end class ResumeAssignment has_one :resume has_one :user end When I delete a resume, I want to make sure that its associated ResumeAssignment gets deleted also. Calling destroy_all to delete some resumes doesn''t seem to do this. Is there an option that will

Can someone clarify this for me? Suppose I have two tables like: class Company < ActiveRecord::Base belongs_to :category end class Category < ActiveRecord::Base has_many :companies end I understand that the belongs_to causes related companies to be read from the db when I ask for a category. I suspect SQL something like select * from categories, companies where category.id

I have two models, Stop and Station, they relate one station to many stops. Stop has_one :station Station belongs_to :stop So I can do @station.stops, but I cant do @stop.station, is this right? For example in the view I have: <% for @stop in @stops %> <tr> <td><%= @stop.station.name %></td> <td><%= @stop.time.hour.to_s + '':''

so when I''m reading the pick axe book second edition I don''t see anything like the syntax you see people using in rails code. Specifically when you see. belongs_to :Person has_many :Phones etc these are methods on ActiveRecord right? Why is this invocation syntax never described in the Pick Axe book? I do see things like attr_reader :some_attribute etc but you

I have two tables: class PgmUpdate < ActiveRecord::Base has_many :pgm_visits, :foreign_key => ''pgm_update_fk'' ... and class PgmVisit < ActiveRecord::Base belongs_to :pgm_update, :foreign_key => ''pgm_update_fk'', :dependent => true ... According to the has_many docs (http://api.rubyonrails.org/classes/

Wow, got myself lost as *soon* as I left the hand-holding exercises in the books. I''m trying to set it up so when I click the (scaffold-generated) ''destroy'' link on one (of a list) of parent MySQL records, the children records in a different table get deleted also. Very simple setup: my tables are ''customers'' and ''accounts'' class

Hello. Using the ":include", which generates a "LEFT OUTER JOIN" SQL command, it is possible to eagerly preload second order data objects (children) for a given association. I wanted to know, if it is possible to eagerly preload and cache third order (or more) data objects, which are little-children or little-little-children. As I''ve seen. it is possible to add

I have two problems. I have a comment that has_many uploads. Before saving the comment, I want to be sure that the upload(s) has passed validation, but I also need to validate in other ways. For example, I do not want to save the comment if there is no comment or upload. Or, I do not want to save the comment if the image has been uploaded previously (comparing md5s with past upload md5s

My problem is that I have two classes where the eager loading isn''t working as well as I would hope... Here are my two classes: class Daynote < ActiveRecord::Base belongs_to :userplace class Userplace < ActiveRecord::Base has_many :daynote, :dependent => true When I show my userplaces, I want to get the associated daynotes with them, so I am doing: @userplace =

Ok, been banging my head on this and just can''t figure it. Normally, any table that has a belongs_to to another table you can easily access it by: table1.table2.field And it works perfectly for one table I have. Let''s call it... tags. So, I''ve got: Tag -> has_many :blah_tags Blah -> has_many :blah_tags Blah_tag -> belongs_to :tag, belongs_to :blah Ok, works

I''m attempting to wrestle an old DB into Rails. This relationship is giving me trouble: class Show < AR::Base has_many :segments end class Segment < AR::Base belongs_to :show has_one :media #this has no PK/FK relation end A Segment is "linked" to Media by Media.name, which is the result of concatenating Segment.name and Segment.part. As I said there are is no

Can anyone point me to a resource for hand coding some sql so I can create my own for the following models: I''m using single table inheritance to store related objects eg: Thumbnail < Image < File :: ActiveRecord:Base Image has_many thumbnails Thumbnail has_one image When I come to list thumbnails I''d like to be able to: 1. List all images relating to a product 2.