relationship

问题 I currently have two Backbone models: user and project. I would like to have a Backbone view containing a form that enables the creation of a new project, and the association of currently existing users (entries from the database users table) with this project. When a user completes this form and clicks the save button, the new project should be saved into the database (in the projects table) and the relationship between the saved project and the related users should be saved into a

问题 I'am using graph database (Neo4j) , and I need to make relations between relations , for example : (user1)-[:FOLLOWED]->(user2) I want to allow other users to like this activity (that user1 followed user2) , what's the best implementation for this ? 回答1: Short answer: You can't create a relation to a relation. How to do? You have to create an activity node in the middle of your relation: (user1)-[:FOLLOWED]->(activity{date:..., blabla:...})-[:ACTIVITY_FOR]->(user2) Then you'll be able to make

问题 I'm working on a new app in Rails 3 but I'm not sure how can I build the relations between the models. Basically I have a model User and a model Project . An user can create a Project, becoming the project owner. But any other user besides the project owner can join this project as well, but as team member. Would I need to create a new model for this team relationship? And how would be the relations among this all? Thanks in advance. 回答1: I'm doing something similar with a photo gallery that

问题 I am building a core data iphone app, and having trouble with retrieving one-many relationship data. Please bear with me while I explain. I have used the data model designer to setup an entity called "Item" that contains many entities called "Comment". I then retrieve multiple entities and display them in a UITableView . I fetch these entities like this (in the viewDidLoad method): NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription

问题 Say I have two collection resources: /persons /organizations A GET to /persons/id/ returns a specific person. Likewise, a GET to /organizations/id returns a specific organization. A person can be member of one or more organizations. In this relation context, we have data such as the role of the person in the organization, the date on which the person joined the organization, ... Which of the designs make most sense? A membership resource /memberships/id , to which a GET returns the data of

问题 Following java doc @Where Where clause to add to the element Entity or target entity of a collection. The clause is written in SQL. A common use case here is for soft-deletes. @WhereJoinTable Where clause to add to the collection join table. The clause is written in SQL. Just as with {@link Where}, a common use case is for implementing soft-deletes. It seems annotations can be used in same way in general: |---------------------|-------------------|-------------------| | |@Where | @WhereTable

问题 I have two models: User and HairColor. A user has only one hair color, but can have many hair color preferences. What's the best way to model this? Here's what I started to do: #models/user.rb class User < ActiveRecord::Base belongs_to :hair_color has_many :preferences, has_many :hair_colors, :through => :preferences end #models/hair_color.rb class HairColor < ActiveRecord::Base has_many :users end #models/preference.rb class Preference < ActiveRecord::Base belongs_to :user belongs_to :hair

问题 I need to query all posts from a specific user and include all comments and the user who belongs to the comment. class User < ... has_many :posts has_many :comments end class Post < ... belongs_to :user has_many :comments end class Comment < ... belongs_to :user belongs_to :post end @posts = current_user.posts.include(:comments) Is is possible to also get the comment user? I list a lot of posts and comments. I do not want to query each comment user. Thx / Tobias 回答1: Try @posts = current_user

问题 I have a three-levels Invoice model which I'd like to display on Django's admin area... in a "kind of special " way. Allow me to provide a bit of background: Each Invoice is conformed by several SubInvoice (s), and each SubInvoice is conformed by several InvoiceItem (s), which contain a break down of the Products purchased by a customer. Logically speaking, it'd be something like this (hopefully the ascii art works) +---------- Invoice id=3 -----------+ | Full total: $100.00 | | | | +-----

问题 I have a: has_and_belongs_to_many :friends, :join_table => "friends_peoples". To add a friend I do: @people.followers << @friend which create the relationship and a new person profile. Now I'd like to delete the relationship ONLY and not the person profile. I tried @people.friends.delete(guilty.id) but it deletes the person profile and not the relationship. Any idea? 回答1: Have you tried this? @people.friends.delete(guilty) 来源： https://stackoverflow.com/questions/3852017/delete-a-has-many