has-and-belongs-to-many

问题 With Rails 3.1.3 on Ruby 1.9.2 , I have: class User < ActiveRecord::Base has_and_belongs_to_many :states end class State < ActiveRecord::Base has_and_belongs_to_many :users end A User is associated with many State s, and a State with many User s. Given a User , I want to find all other User s who are in any of her states. I tried: class User < ActiveRecord::Base scope :in_state, lambda { |states| joins(:states).where(:states => states) } end User.in_state(current_user.states).all With this

问题 I understood that every new row, causes the deletion of the rows that were there before? What is the idea behind it? I don't believe that it is .. So, what am i getting wrong? Edit A I have a form that adds a store to the Stores table. the store have a column named owner_id which is associated to the Users table through a belongsTo relationship. There is also a table named stores_users that supposed to store the mangers for each store, using the HABTM relationship. For this table there is a

问题 Working with an has_and_belongs_to_many_association class Category has_and_belongs_to_many :projects end I would would like to use a before_filter to set projects before saving categories before_filter :set_projects, :only => [:create, :update] def set_projects @category.assign_attributes({projects: Project.all}) end This works well, except when the category cannot be saved and there is a rollback. The projects are still updated in database. Why this line @category.assign_attributes({projects

问题 For an e-commerce app that I'm building I am using CakePHP. I have created the db and afterwards baked my app with cake bake . My models are all linked up properly as follows: Product hasMany CategoryProduct,ImagesProduct Category hasMany CategoryProduct CategoryProduct belongsTo Product,Category Image hasMany ImagesProduct ImagesProduct belongsTo Product,Image I have tried in various ways to obtain a paginated view of products dependent of the category_id with no succes. I have managed to

问题 So I have three models: Coach: var $hasAndBelongsToMany = array("Tour") Tour: var $hasAndBelongsToMany = array("Coach") CoachesTour: var $belongsTo = array("Tour", "Coach") There is an HABTM association between Coach and Tour, and it should use the CoachesTour as the join model. I'm using scaffold. When modifying a Tour, if I add a new CoachesTour to it, the beforeSave method of CoachesTour isn't called. It seems as if the records of the join model are being inserted as SQL statements,

问题 I've been tinkering with this for some time now, and can't seem to figure this out. It's probably something simple, but here goes: I have a has_many :trough relationship between 'laminate', and 'standards' with a joined model 'standardization'. Standard.rb class Standard < ActiveRecord::Base attr_accessible :description, :name has_many :standardizations has_many :laminates, :through => :standardizations end Standardization.rb class Standardization < ActiveRecord::Base attr_accessible

问题 This is only my 3rd CakePHP app, and the first to require a HABTM type association. I'm working with Cake 2.1, in which there was a change to HABTM parameters allowing for extra information to be saved by setting the 'unique' key to 'keepExisting'. In a normal HABTM association you have a table with 2 fields, each foreign keys. I think I need one with 3 foreign keys. Is that possible by using the 'unique' key, or should I use a hasMany through association? Here's my schema: /* repair_orders *

问题 I'm a rails noob working on my first own project. I got two models linked using a has_and_belongs_to_many relationship : Wine and Shop . To make it simple a wine can be sold in different shops and a specific shop can sell many different wines. Here are the models : class Shop < ActiveRecord::Base has_and_belongs_to_many :wines end class Wine < ActiveRecord::Base has_and_belongs_to_many :shops end My goal is to make a form to create instances of Wine including the Shops where the wine can be

问题 I'm trying to build a CMS with Nodes as the main model. Each Node belongsTo a NodeType , and every Node can be related to any/every other Node . So - thought this called for HABTM: //Node model public $hasAndBelongsToMany = array( 'AssociatedNode' => array( 'className' => 'Node', 'foreignKey' => 'node_id', 'associationForeignKey' => 'associated_node_id', 'joinTable' => 'node_associations' ) ); The problem is, it seems like the only way it works is if I have TWO rows for each association.

问题 I have an invoice form. This is a simplified version: so it has line items where you select a drop down menu of product names. This is working well: So the invoice-line_item relations is this: invoice has_many line_items and line_item belongs to invoice. line_item belongs to item and item has_many line_items. I have the items, line_items and invoice setup correctly. But now I want to add taxes to the line items. So I created a line_items_taxes table to create a HABTM relationship between line