has-many

I am new to Backbone-relational, I am not sure what is the right way to use HasMany. I have a Parent model which have many children (by "many" I mean thousands of children). In order to avoid performance issue, I query children by their foreign key: /child/?parent=1 , instead of create a huge list of child_ids in Parent . But seems this is not the way Backbone-relational work. So I am wondering what is the right way to handle this. 1, Change my json api to include list of child id in parent, then send thousands of ids as Backbone-relational recommend: url = function(models) { return '/child/'

I've been playing around with STI and belongs_to / has_many relationships and I'm a bit confused. I have a few questions based on a model configuration similar to: class Parental < ActiveRecord::Base end class Mother < Parental has_many :babies end class Father < Parental has_many :babies end class Baby < ActiveRecord::Base belongs_to :?????? end What should Baby belong_to? In terms of a migration, what should i name/add for foreign key on the babies table? I've had a hard time researching this, is there a definitive source that explains this? The API docs did not seem to hit it on the head OR

I try to create a polymorphic association, what is common in Rails but unfortunately not in Yii2. As part of the implementation I need to define the relation: public function getImages() { return $this->hasMany(RecipeImage::className(), ['imageable_id' => 'id', 'imageable_type' => 'Person']); } But this doesn't work, because 'Person' is treated as an attribute of the current model, but it is a constant (class name for the polymorphic association). If I try to use 'andWhere' it adds the condition of course in a WHERE clause instead of the ON clause, causing that only records with existing image

While I'm not a complete Ruby/Rails newb, I'm still pretty green and I'm trying to figure out how to structure some model relationships. The simplest example I can think of is the idea of "recipes" for cooking. A recipe consists of one or more ingredients and the associated quantity of each ingredient. Assume we have a master list in the database of all ingredients. That suggests two simple models: class Ingredient < ActiveRecord::Base # ingredient name, end class Recipe < ActiveRecord::Base # recipe name, etc. end If we just wanted to associate Recipes with Ingredients, that's as simpling as

Following are the 1-to-M models: class FotoGossip < ActiveRecord::Base has_many :uploads attr_accessible :published_at, ... end class Upload < ActiveRecord::Base belongs_to :foto_gossip end Now I want the Uploads.all with the condition :published_at NOT NULL of the corresponding upload's parent model? Just add this to your Upload model: named_scope :with_published_foto_gossip, :joins => :foto_gossip, :conditions => "foto_gossips.published_at IS NOT NULL" then you can get all the uploads with published foto_gossip like this: Upload.with_published_foto_gossip 来源： https://stackoverflow.com

I was considering adding some extra properties between a has_many relationship. For example, I have a Users table, and a Group table. Users can join groups via a :through has_many relationship. I want to add the property of the 'role' of the user in that group. create_table "groupization", :force => true do |t| t.integer "user_id" t.integer "group_id" t.string "role" t.datetime "created_at", :null => false t.datetime "updated_at", :null => false end I was wondering, how can I access the role attribute. I was thinking something like: user.groups[0].role Is that a correct approach? I know the

I'm using Rails 1.2.3 (yeah, I know) and am confused about how has_many works with respect to object persistence. For the sake of example, I'll use this as my declaration: class User < ActiveRecord::Base has_many :assignments end class Assignment < ActiveRecord::Base belongs_to :user end As I understand it, this generates, among others, a method User#assignments.build , which creates an Assignment object whose user_id is the receiving instance's id (and whose other fields are as specified in the argument), but does not save this object in the database. The object can be saved later by calling