associations

问题 Banging my head against this one for a long time. On Rails 2.3.2, Ruby 1.9.1. Trying to use one form to create three objects that have these relations: class Person has_one :goat end class Goat belongs_to :person has_many :kids end class Goat::Kid belongs_to :goat end Here's a summary of the schema: Person first_name last_name Goat name color Goat::Kid nickname age I'd like my #create action to instantiate new instances of all three models with the specified associations. However, while it

问题 I have an invoice form. This is a simplified version: so it has line items where you select a drop down menu of product names. This is working well: So the invoice-line_item relations is this: invoice has_many line_items and line_item belongs to invoice. line_item belongs to item and item has_many line_items. I have the items, line_items and invoice setup correctly. But now I want to add taxes to the line items. So I created a line_items_taxes table to create a HABTM relationship between line

问题 My model structure looks like this: Board has_many Topics. Topic has_many Posts. app/models/board.rb class Board < ActiveRecord::Base has_many :topics end app/models/topic.rb class Topic < ActiveRecord::Base belongs_to :user belongs_to :board has_many :posts accepts_nested_attributes_for :posts validates :title, presence: true, length: { maximum: 255 } validates :user_id, presence: true validates :board_id, presence: true ... end app/models/post.rb class Post < ActiveRecord::Base belongs_to

问题 This seems like a bug in Rails to me, but there's probably not much I can do about that. So how can I accomplish my expected behavior? Suppose we have: class User < ActiveRecord::Base has_many :awesome_friends, :class_name => "Friend", :conditions => {:awesome => true} end And execute the code: >> my_user.awesome_friends << Friend.new(:name=>'jim') Afterwards, when I inspect this friend object, I see that the user_id field is populated. But I would also expect to see the "awesome" column set

问题 I am looking for a good solution for a probably typical problem of managing models with HABTM association in Rails. Let's assume that we have two models -- products and categories: Products has_many :categorizations has_many :categories, :through => :categorizations Categories has_many :categorizations has_many :products, :through => :categorizations Categorization belongs_to :product belongs_to :category Pat Shaughnessy is developing modified auto_complete plugin which can allow to manage

问题 Please help to understand how to do @project.payments having this tree: Project |__Stages |__Costs |__Payments project.rb has_many :stages has_many :costs, :through => stages stage.rb belongs_to :project has_many :costs has_many :payments :through => costs cost.rb belongs_to :stage has_many :payments payment.rb belongs_to :cost 回答1: Note: As this is a nested has_many :through relationship, it'll only work in Rails 3.1+ (RC4 of 3.1 is out) project.rb has_many :payments, :through => costs 来源：

问题 Both Attendment & Vouching: belongs_to :event belongs_to :account Therefore: 1 to 1 relationship between attendments and vouchings. Is there a way to do this without my thinking too much? # attendment has_one :vouching :through => [:event, :account] Note: I don't mind thinking too much, actually. 回答1: Yeah i don't think you can use a has_one for this. Assuming I'm reading this correctly, you have two models: Attendment Vouching They both store an event_id and account_id. You want to know from

问题 I have two models. User and Account as follows class Account < ActiveRecord::Base has_many :manages has_many :users, :through => :manages end class User < ActiveRecord::Base has_many :manages has_many :accounts, :through => :manages end If I were to use the rails console and create an instance of account by acc = usr.accounts.build acc.save The following command would return the account instance created usr.accounts But the following command would not return the user instance acc.users Also

问题 I am using Ruby on Rails v3.2.2 and, after post my previous question, I would like to know and understand if (or not) to explicitly validate foreign keys related to ActiveRecord::Associations is needed. For example: class CategoryAssociation < ActiveRecord::Base belongs_to :article, :foreign_key => 'article_id' belongs_to :category, :foreign_key => 'category_id' validates :article_id, :presence => true, :numericality => { :only_integer => true } validates :category_id, :presence => true,

问题 model Post # ActiveRecord associations have tons of options that let # you do just about anything like: has_many :comments has_many :spam_comments, :conditions => ['spammy = ?', true] # In Rails 3, named scopes are ultra-elegant, and let you do things like: scope :with_comments, joins(:comments) end Is there any way to use AREL, or an otherwise leaner syntax, to define custom associations as elegantly as named scopes? update I've decided it's not a good idea to put that sort of detail into an