polymorphic-associations

问题 I have Rails polymorphic model and I want to apply different validations according to associated class . 回答1: The class name is in the _type column for instance in the following setup: class Comment belongs_to :commentable, :polymorphic => true end class Post has_many :comments, :as => :commentable end the comment class is going to have the commentable_id and commentable_type fields. commentable_type is the class name and commentable_id is the foreign key. If you wanted to to a validation

问题 I'm making an app with the following attributes, and I'm working on a creating a single form to be able to save a goal, a goal's tasks, a goal's milestones, and a milestone's tasks. #app/models/goal.rb has_many :tasks, :as => :achievement has_many :milestones accepts_nested_attributes_for :tasks accepts_nested_attributes_for :milestones #app/models/milestone.rb belongs_to :goal has_many :tasks, :as => :achievement #app/models/task.rb belongs_to :achievement, :polymorphic => true Whenever I

问题 I have an Activity model. It belongs_to :parent, :polymorphic => true . Does Rails use parent.class.name , parent.model_name or something else to populate the parent_type field? I want a Presenter to behave like the parent object it wraps, and I need to override the right method. Thanks. 回答1: I'm working with Rails 3.0.7 right now, and the polymorphic type is being defined in active_record-3.0.7/lib/active_record/association.rb , line 1773. def create_belongs_to_reflection(association_id,

问题 I am working on my first polymorphic association relationship and I am having trouble refactoring my form_for create comments. I tried going through the Polymorphic Association RailsCasts http://railscasts.com/episodes/154-polymorphic-association?view=asciicast, but it seems dated. I have two questions: How do I rewrite my comment_form partial so that it would work for anything commentable? The way I have it right now, it would only work for traveldeals since (:commentable_id => @traveldeal

问题 I am using a legacy database, so i do not have any control over the datamodel. They use a lot of polymorphic link/join-tables, like this create table person(per_ident, name, ...) create table person_links(per_ident, obj_name, obj_r_ident) create table report(rep_ident, name, ...) where obj_name is the table-name, and obj_r_ident is the identifier. So linked reports would be inserted as follows: insert into person(1, ...) insert into report(1, ...) insert into report(2, ...) insert into person

问题 I am trying to create an associated polymorphic object through fields_for. I am getting an unknown attribute error though when the parent is created, are the @order params not getting through somehow? Parent/Order controller - # GET /orders/new def new @order = Order.new @order.build_patient @order.product = OrthosisSpecification.new end # GET /hotels/1/edit def edit @order.build_patient end # POST /orders # POST /orders.json def create @order = Order.new(order_params) respond_to do |format|

问题 I've read some of Bill Karwin's answers about single table inheritance and think this approach would be good for the setup I am considering: Playlist -------- id AUTO_INCREMENT title TeamPlaylist ------------ id REFERENCES Playlist.id teamId REFERENCES Team.id UserPlaylist ------------ id REFERENCES Playlist.id userId REFERENCES User.id PlaylistVideo ------------- id playlistId REFERENCES Playlist.id videoId REFERENCES Video.id All the CASCADE options are set to DELETE which will work

问题 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

问题 Hey all, I have something of an interesting requirement for my project. I need a has_one relationship where it is either one class or the other, but without inheritance. I could get away with inheritance if it is the only way, but the two associate records have completely different data and aren't related at all. What I need to figure out is something like the following. # 1. Foo never belongs to anything. # 2. Foo MUST have one assigned sub-record for validity. # 3. Foo can only have either

问题 Hey all, I have something of an interesting requirement for my project. I need a has_one relationship where it is either one class or the other, but without inheritance. I could get away with inheritance if it is the only way, but the two associate records have completely different data and aren't related at all. What I need to figure out is something like the following. # 1. Foo never belongs to anything. # 2. Foo MUST have one assigned sub-record for validity. # 3. Foo can only have either