has-many

问题 With these models: class Week has_many :proofs end class Proof belongs_to :week end I want to do something like: Week.where(:proof.count.gt => 0) To find only weeks that have multiple proofs. There is one answer that seems to address this: Can rails scopes filter on the number of associated classes for a given field But in this example, there is no such attribute as proof_ids in Week since the ids are stored with the proofs. This does not work for example: Week.where(:proof_ids.gt => 0) How

问题 I'm setting up a simple ruby/rails app where users can review albums. On an album's show page I average all the user reviews associated with that album through this code in my albums controller def show @album = Album.find_by_id(params[:id]) if @album.reviews.present? @ratings = Review.where(album_id: @album).average(:rating).truncate(2) else render 'show' end end This gives me an average rating for each album. On my home page (routed through a different controller) I want to display the top

问题 My problem looks as follows: I want to make a vote app where People can choose one or more Events(like Doodle). For this I have set up a function called vote. In the View you can choose the Events using checkboxes. The Models are Poll and Groupevent. A Poll has Many Groupevents. My Problem is when I call updateAll() , all values of the associated Groupevents are incremented. Here is my code: View: echo $this->Form->create('Poll', array('action' => 'vote')); for($i=0; $i<$count; $i++){ echo

问题 I have domain like this: class Team { hasOne [leader: Person] hasMany [member: Person] } class Person { belongsTo [team: Team] } But when the tables are generated, there is not a column like leader_id in the team table. And thus the leader relation is not persisted. How should I fix it? 回答1: I figured that, what I need is class Team { belongsTo [leader: Person] hasMany [member: Person] } class Person { belongsTo [team: Team] } so that the Team table can have the desired "leader" reference

问题 I have a database with 6500 players and each player has an average of 15 game results . Use case I want to generate a list of players, ordered by the sum of their prize money (a field in the results table). I prefer this to be in some sort of scope, so I can also filter the list on the player's country, etc. Performance I have seen posts that mention a cache_counter field for performance. In my case I have thousands of result records (75.000+) so I don't want the calculations being done every

问题 how I can get the has_many associations of a model? For example if I have this class: class A < ActiveRecord::Base has_many B has_many C end I would a method like this: A.get_has_many that return [B,C] Is it possible? Thanks! 回答1: You should be using ActiveRecord reflections. Then you can type something like this: A.reflect_on_all_associations.map { |assoc| assoc.name} which will return your array [:B, :C] 回答2: For Example you could try : aux=Array.new Page.reflections.each { |key, value| aux

问题 This question already has answers here : Want to find records with no associated records in Rails (8 answers) Closed 5 months ago . This seems fairly simple but I can't get it to turn up on Google. If I have: class City < ActiveRecord::Base has_many :photos end class Photo < ActiveRecord::Base belongs_to :city end I want to find all cities that have no photos. I'd love to be able to call something like... City.where( photos.empty? ) ...but that doesn't exist. So, how do you do this kind of

问题 New to both Ruby and Rails but I'm book educated by now (which apparently means nothing, haha). I've got two models, Event and User joined through a table EventUser class User < ActiveRecord::Base has_many :event_users has_many :events, :through => :event_users end class EventUser < ActiveRecord::Base belongs_to :event belongs_to :user #For clarity's sake, EventUser also has a boolean column "active", among others end class Event < ActiveRecord::Base has_many :event_users has_many :users,

问题 I have the following model relationships: class Article < ActiveRecord::Base has_many :tags, :through => :article_tags end class ArticleTag < ActiveRecord::Base belongs_to :tag belongs_to :article end class Tag < ActiveRecord::Base has_many :articles, :through => :article_tags end Now I want to load all the Articles that are tagged with both tag "A" and tag "B". I'm pretty new to Rails and it has been a few years since I did any serious web-dev/SQL work but for the life of me I can't figure

问题 I have an NHibernate map which defines a HasMany-relationship on a type, i.e. a class has a list of another class. I would like NHibernate to be able to read uncommitted data including the list resulting from the HasMany-relationship. I have isolationlevel ReadUncomitted and I am able to write data and read it back before committing. However, the list is always empty, unless I commit first. Is there a way to make NHibernate populate objects with data from HasMany-relationships? EDIT It turns