associations

问题 I have four models: class User < ActiveRecord::Base has_many :posts end class Category < ActiveRecord::Base has_many :posts end class Post < ActiveRecord::Base belongs_to :user belongs_to :metric has_many :comments end class Comments < ActiveRecord::Base belongs_to :post end I'd like to be able to access a post within a certain category for a specific user. For example: http://domain.com/users/1/categories/1/posts Also I want to see a list of all categories if I visit: http://domain.com/users

问题 If form fails validation, fields for has_many association, disappears from view: my new action looks like def new @realty = Realty.new @realty.build_user @realty.build_address #user, address are has_one association, and they stay in view after failed validation 6.times { @realty.realty_images.build } # and this one vanishes away respond_to do |format| format.html # new.html.erb format.json { render json: @realty } end end if I add to my form this snippet - if @realty.realty_images.empty? - 6

问题 I have successfully set up a friendship self referencial association for users in my Ruby on Rails app after following Ryan Bates' railscast. I can successfully follow, unfollow, and view who is following. Now I want to pull in another element and I am not sure how to do it. When visiting a user/show page of a user that the current_user is already friends with...what is the syntax for checking the Friendships table for an existing friendship. Here is how the associations are set up.

问题 There is one example to explaining associations in UML. A person works for a company; a company has a number offices. But I am unable to understand the relationship between Person, Company, and Office classes. My understanding is: a company consists of many persons as employees but these classes exist independently so that is simple association with 0..* multiplicity on Person class' end a company has many offices and those offices will not exist if there is no company so that is composition

问题 I want to use chartkick to create a line graph of records, which belong to a planned task. In other words: plantask has_many records Records has two fields I'm interested in graphing. The created_at, which will be my X-axis, and data(An integer), which will be my Y-axis. So far I've gotten pretty close. By inserting this into my view: <%= line_chart @plantask.records.group_by_day(:created_at).sum(:data) %> I can see that my x-axis is displaying perfectly. However, it appears that the y-axis

问题 I have a Ruby on Rails application setup like so: User Model has_and_belongs_to_many :roles Role Model has_many :transactions has_and_belongs_to_many :users Transaction Model belongs_to :role This means that a join table is used called roles_users and it also means that a user can only see the transactions that have been assigned to them through roles, usage example: user = User.find(1) transactions = user.roles.first.transactions This will return the transactions which are associated with

问题 Current the following exists: Listing Entity class Listing { /** * @var integer $id * * @ORM\Column(name="listing_id", type="integer") * @ORM\Id * @ORM\GeneratedValue(strategy="AUTO") */ private $id; /** * @var string $title * * @ORM\Column(name="title", type="string", length=255) */ private $title; /** * @ORM\ManyToOne(targetEntity="IntA\UserBundle\Entity\User", cascade ={"delete"}, inversedBy="listings") * @ORM\JoinColumn(onDelete="CASCADE") */ protected $user; /** * @ORM\OneToMany

问题 Using the Rails 4.1.4 framework. Having a problem adding a 'friend_id' to the user_friendships table below... when the program runs in rails, I am redirected to the root (as expected) and given the success message that the friendship was created. However, when I crack open the database GUI, I see that only a user_id is saved into the user_id column, and the friend_id column is always left 'nil', no matter who friends who. I've searched high and low - I know it must be something simple and it

问题 I'm trying to do a has_many relation with a table on creation and also to add it in another table already created. I have my User table already with no relations. I want to create a Pro_user with a relation has_many User . The thing is that one User can have multiple Pro_user and a Pro_user can also also have multiple User . So both tables need a has_many right ? So what I thought of was that rails g model pro_user name:string email:string password_digest:string user:references But this is

问题 i have two model 'Asset' , and 'User' .'Asset' can be assigned to one 'user' and 'asset' is created by one 'user'.here is detail of model classes class Asset < ActiveRecord::Base belongs_to :assigned_to ,:class_name=>'User' belongs_to :creator ,:class_name=>'User' end and class User < ActiveRecord::Base has_many :assets end now in assets show.html.erb i can access name of creator with @asset.creator.name but i can not see name of 'assigned_to' @asset.assigned_to.name #gives nothing both