associations

问题 In my model "Post.rb", I'm trying to have it only return posts if column deleted is 0. In other words, when the user deletes posts, it doesn't remove the item from the database, but rather turns deleted to 1. So if I run Post.find(:all), I want it to automatically add the condition "deleted = '0'". How do I go about doing this from my model? Thanks! 回答1: Yes, default_scope is going to be simplest method and will allow you to continue using things like Post.find(:all) without worrying about

问题 I am implementing triply nested form where you can see I am also showing the triply nested Task model's content and also rendering a form to add new Task. The task list is displayed correctly- which means the fet has a valid Feature model, But dont know why it is failing when rendering the new task form unexpectedly!! where it shows-> ActionController::UrlGenerationError in Projects#show No route matches {:action=>"index", :controller=>"tasks", :feature_id=>nil}, missing required keys: [

问题 User and Organization have a many-to-many association through Relationship . One of the variables in the Relationship model is a boolean called member . A user can occur in the Relationship model multiple times as a user can be related to multiple organizations . How can I select a random instance from all the users that 1) don't have a relationship with any organization (so don't occur in the Relationship model) plus 2) those users that do have a relationship with an organization but for

问题 I want to fetch username or email( both are in user table) of user who creates article in blog application. Currently I am able to fetch user id from articles_controller.rb def create @article = Article.new(params[:article]) @article.user_id = current_user.id @article.save redirect_to article_path(@article) end but no idea how to fetch username or email for same. Basically I want to display username or email on article index page. Please suggest me to how to get done it user.rb class User <

问题 I'm trying to sort a table of data. I have the following domain (paraphrased and example-ified): class Car { Engine engine static constraints = { engine nullable: true // poor example, I know } } class Engine { String name } Here's the controller action that's handling the sort: def myAction = { def list = Car.findAll(params) render(view: 'list', model: [list: list]) } I provision some data such that there are several Cars, some with null engines and others with engines that are not null. I

问题 I am working on a program that is supposed to simulate bank accounts. I have my base class called "Investment", my two subclasses called "Stock" and "MutualFund", and I also have a class called "CustomerAccount" that is supposed to be associated with the base class "Investment". I'm not sure how to associate the CustomerAccount class with the Investment class. 回答1: The CustomerAccount class has a "CanHave" relationship with Investment. In your CustomerAccount class, create a collection of

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 5 years ago . Standard object modelling identifies attributes, aggregates and associations of objects. You must conform to several requirements when implementing the equals() method of a class. There is plenty of advice available on how to write this method, including pitfalls to avoid.

问题 I am trying to select specific record but when trying to save , employee_id is saved with a null value, and without putting any condition it works normally , is there any way to solve this ? <%= f.association :employee , collection: Employee.where('student_advisor' => true).map(&:full_name) %> 回答1: This is what works for me: <%= f.association :employee, :collection => Employee.where('student_advisor' => true), :label_method => :full_name, :value_method => :id %> Though IMHO its better to set

问题 here is my table association code: class UserMastersTable extends Table { public function initialize(array $config) { parent::initialize($config); $this->table('user_masters'); $this->hasOne('person_masters', [ 'className' => 'person_masters', 'foreign_key'=>'user_master_id', 'dependent' => true ]); } } when in controller i am using: $this->UserMasters->get($id); it results only user_masters table data.. so how can i also get Associated tables data?? 回答1: Use contain() Copy-Paste from the

问题 Giving an analogy: Twitter like scenario where in a person can be followed by huge number of people (one-to-many) , Few options which I could think of Use some OR mapping tool with lazy loading. But when you access the "followers" side of relations, it will still load all the data even tough lazily. So not a suitable option. Do not maintain one-to-many relation (or not use any OR mapping) . Fetch the "Followers" side in separate call and handle the paging etc programmatically. Offload