has-many-through

I have a has_many through join table setup for a recipe app where Ingredient and Meal connect through MealIngredient . Within MealIngredient , I have meal_id , ingredient_id , and amount . My question is: How can I save and update the amount column in the meal form? My form field for adding an ingredient looks like this: <% Ingredient.all.each do |ingredient| %> <label> <%= check_box_tag "meal[ingredient_ids][]", ingredient.id, f.object.ingredients.include?(ingredient) %> <%= ingredient.name %> </label> <br /> <% end %> How do I save the amount for each ingredient? I am referencing this

Let's say I have the following 4 tables (for examples' sake): Owners, Trucks, Boxes, Apples. An owner can have many trucks, a truck can have many boxes and a box can have many apples. Owners have an id. Trucks have an id and owner_id. Boxes have an id and truck_id. Apples have an id and box_id. Let's say I want to get all the apples "owned" by an owner with id = 34. So I want to get all the apples that are in boxes that are in trucks that owner 34 owns. There is a "hierarchy" if you will of 4 tables that each only has reference to its direct "parent". How can I quickly filter boxes while

It seems ActiveRecord's counter_cache feature can result in a counter cache being incremented twice. The scenario in which I am seeing this behavior is when I have two models that have a has_many :through relationship with each other through a join model (ie: Teacher has many Student through Classroom ). When using the has_many :through generated methods to associate Teacher and Student directly (without manually creating the join record) the count goes up 2 times. Example: teacher.students << Student.create(name: "Bobby Joe") causes teacher.students_count to increment by 2. Please help me

I'm having problems building an association that is a has_many :through with conditions. I have this model: class Contact < AR has_many :group_contacts has_many :groups, :through => :group_contacts, :conditions => {:groups => {:published => true}} end problem happens when I try to instantiate a group from a contact. With the above syntax, I get an error: contact.groups.build => ActiveRecord::UnknownAttributeError: unknown attribute: groups But when I use the following syntax it works: has_many :groups, :through => :group_contacts, :conditions => ['groups.published = ?', true] contact.groups

Is there a way to dynamically add after_add and after_remove callbacks to an existing has_many or has_and_belongs_to_many relationship? For example, suppose I have models User , Thing , and a join model UserThingRelationship , and the User model is something like this: class User < ActiveRecord::Base has_many :user_thing_relationships has_many :things, :through => :user_thing_relationships end I'd like to be able to, in a module that extends User , add :after_add and :after_remove callbacks to the User.has_many(:things, ...) relationship. I.e., have something like module DoesAwesomeStuff def

In my models I have the following setup: class User < ActiveRecord::Base has_many :assignments has_many :roles, :through => :assignments end class Role < ActiveRecord::Base has_many :assignments has_many :users, :through => :assignments end class Assignment < ActiveRecord::Base belongs_to :user belongs_to :role attr_accessible :role_id, :user_id end In my factory.rb file I have: FactoryGirl.define do factory :user do sequence(:username) { |n| "user#{n}" } email { "#{username}@example.com" } password 'secret' password_confirmation 'secret' factory :admin do ... end end factory :role do name

I have two models I link together using a polymorphic has_many through association and I would like to add a counter_cache but it seems Rails/ActiveRecord does not support this feature out of the box. class Classifiable < ActiveRecord::Base has_many :classifications, :as => :classifiable, :foreign_key => :classifiable_id end class Taxonomy < ActiveRecord::Base has_many :classifications, :as => :taxonomy, :foreign_key => :taxonomy_id end class Question < Classifiable has_many :categories, :through => :classifications, :as => :classifiable, :source => :taxonomy, :source_type => "Category" end