I've search everywhere for a pointer to this, but can't find one. Basically, I want to do what everyone else wants to do when they create a polymorphic relationship in a :has_many, :through way… but I want to do it in a module. I keep getting stuck and think I must be overlooking something simple.
To wit:
module ActsPermissive
module PermissiveUser
def self.included(base)
base.extend ClassMethods
end
module ClassMethods
def acts_permissive
has_many :ownables
has_many :owned_circles, :through => :ownables
end
end
end
class PermissiveCircle < ActiveRecord::Base
belongs_to :ownable, :polymorphic => true
end
end
With a migration that looks like this:
create_table :permissive_circles do |t|
t.string :ownable_type
t.integer :ownable_id
t.timestamps
end
The idea, of course, is that whatever loads acts_permissive will be able to have a list of circles that it owns.
For simple tests, I have
it "should have a list of circles" do
user = Factory :user
user.owned_circles.should be_an_instance_of Array
end
which fails with:
Failure/Error: #user.circles.should be_an_instance_of Array
NameError: uninitialized constant User::Ownable
I've tried: using :class_name => 'ActsPermissive::PermissiveCircle' on the has_many :ownables line, which fails with:
Failure/Error: #user.circles.should be_an_instance_of Array
ActiveRecord::HasManyThroughSourceAssociationNotFoundError:
Could not find the source association(s) :owned_circle or
:owned_circles in model ActsPermissive::PermissiveCircle.
Try 'has_many :owned_circles, :through => :ownables,
:source => <name>'. Is it one of :ownable?
while following the suggestion and setting :source => :ownable fails with
Failure/Error: #user.circles.should be_an_instance_of Array
ActiveRecord::HasManyThroughAssociationPolymorphicSourceError:
Cannot have a has_many :through association 'User#owned_circles'
on the polymorphic object 'Ownable#ownable'
Which seems to suggest that doing things with a non-polymorphic-through is necessary. So I added a circle_owner class similar to the setup here:
module ActsPermissive
class CircleOwner < ActiveRecord::Base
belongs_to :permissive_circle
belongs_to :ownable, :polymorphic => true
end
module PermissiveUser
def self.included(base)
base.extend ClassMethods
end
module ClassMethods
def acts_permissive
has_many :circle_owners, :as => :ownable
has_many :circles, :through => :circle_owners,
:source => :ownable,
:class_name => 'ActsPermissive::PermissiveCircle'
end
end
class PermissiveCircle < ActiveRecord::Base
has_many :circle_owners
end
end
With a migration:
create_table :permissive_circles do |t|
t.string :name
t.string :guid
t.timestamps
end
create_table :circle_owner do |t|
t.string :ownable_type
t.string :ownable_id
t.integer :permissive_circle_id
end
which still fails with:
Failure/Error: #user.circles.should be_an_instance_of Array
NameError:
uninitialized constant User::CircleOwner
Which brings us back to the beginning.
How can I do what seems to be a rather common polymorphic :has_many, :through on a module?
Alternatively, is there a good way to allow an object to be collected by arbitrary objects in a similar way that will work with a module?
It turns out that adding :class_name to both :has_many definitions will actually work (someone commented on that, but they deleted their comment). It didn't work in my non-simplified program because of something else in my program that was causing a cascading error that SEEMED to be local to the :has_many definition.
Short story: It was a lot of trouble for something that wasn't actually a problem. Blech
Related
One thing about active record that has been confusing me (I'm still kinda new with rails). I'm doing a migration like so:
def up
change_table :slide do |t|
t.references => :slideable, :polymorphic => true
end
end
and then I'll modify my models thus:
class Slide < BaseModel
...
belongs_to :slideable, :polymorphic=>true
end
class Painting < BaseModel
...
has_one :slide, :as => :slideable
end
class Paper < BaseModel
...
has_one :slide, :as => :slideable
end
Do I also have to do a migration for the has_one relationships on Painting and Paper in order to be able to use both sides of the association?
slide.painting.name
slide.paper.title
painting.slide.name
paper.slide.name
No, has_one does not affect your database. belongs_to is what will actually create a foreign key field in your table, that is why you need a migration.
'm trying to tweek Spree to my needs and I've hit a bump. I'll try to explain as best as I can without pasting too much code, 'cause Spree has quite a lot of it...
For starters. I've extended OptionType like this
Spree::OptionType.class_eval do
PRODUCT_TYPES = SuperMap.new( [:default, 0],
[:vehicle_bonnet, 1],
[:vehicle_images, 2])
super_mapped_attr :product_type, PRODUCT_TYPES
attr_accessible :product_type
end
I want to check in the show view of the ProductsController what sort of product_type I'm dealing with, like this:
<% if #product.option_types.product_type_key == :vehicle_bonnet %>
...
<% end %>
and I get undefined method ``product_type_key'. This method should be available thanks to SuperMap.
Now, the Product and OptionType has a bit strange association (for me at least).
module Spree
class Product < ActiveRecord::Base
has_many :product_option_types, :dependent => :destroy
has_many :option_types, :through => :product_option_types
end
end
so far seems to be ok.
module Spree
class ProductOptionType < ActiveRecord::Base
belongs_to :product
belongs_to :option_type
acts_as_list :scope => :product
end
end
and now comes the weird part:
module Spree
class OptionType < ActiveRecord::Base
has_many :option_values, :order => :position, :dependent => :destroy
has_many :product_option_types, :dependent => :destroy
has_and_belongs_to_many :prototypes, :join_table => 'spree_option_types_prototypes'
attr_accessible :name, :presentation, :option_values_attributes
validates :name, :presentation, :presence => true
default_scope :order => "#{self.table_name}.position"
accepts_nested_attributes_for :option_values, :reject_if => lambda { |ov| ov[:name].blank? || ov[:presentation].blank? }, :allow_destroy => true
end
end
this is actually the whole OptionType model. What suprises me it doesn't have has_many :products, through: :product_option_types. I've tried to add this line to my extension, but didn't help. I've tried few other thing of course, but it just made such a mess I went back to this version, since I think it shows best what I'm trying to achieve. What am I missing?
EDIT (solved, I should hope so...):
Turned out that in the Product model there was an alias alias :options :product_option_types, which was (imho) in the wrong place, because somewhere in the middle of a quite a long model (I should think it should have been somewhere closer to the has_many, but that's just me).
Further more, the options turned out to be an array, no that shocking come to think of it. So, what I did is extended the product model, added a method, where I'm checking the product_type_key, like so:
def type_of_product?(type)
options.each do |opts|
if opts.option_type.product_type_key == type
return true
end
end
false
end
Not the prettiest method, but it works as I expect it to...
I have a Model called Challenge that is created by a User. It has a Difficulty associated with it as well. When I create the Challenge and hand it the Author (User) and Difficulty, the Difficulty associate works, but the Author (User) one doesn't. The weirdest part is, when you look at the Challenge object, it shows the Author key its associated with.
challenge = Challenge.first
challenge.author (prints Nil) #Doesn't even run a Query
When I create a Challenge using the following code, the user_id is Nil.
user = User.find(1)
diff = Difficulty.find(1)
Challenge.create(:author => user, :difficulty => diff, :title => "My Challenge")
When I create a Challenge using this code, the User gets the relation to the Challenge and the Challenge gets the user_id of the User. But you can only go from User to Challenge. Challenge to User returns Nil.
user = User.find(1)
diff = Difficulty.find(1)
chall = Challenge.create(:difficulty => diff, :title => "My Challenge")
user.authored_challenges << chall
Here are my Models and Tables
# Models
class User < ActiveRecord::Base
has_many :authored_challenges, :class_name => "Challenge"
attr_accessible :display_name, :authored_challenges
end
class Reward < ActiveRecord::Base
has_many :challenges
attr_accessible :name, :value, :challenges
end
class Challenge < ActiveRecord::Base
belongs_to :reward
belongs_to :author, :class_name => "User"
attr_accessible :title, :description, :reward, :author
end
# Tables
create_table :users do |t|
t.string :display_name
t.timestamps
end
create_table :rewards do |t|
t.string :name
t.float :value
t.timestamps
end
create_table :challenges do |t|
t.integer :user_id
t.integer :reward_id
t.string :title
t.string :description
t.timestamps
end
According to: http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html the foreign key should be:
:foreign_key => :author_id
Don't forget to add the field. Good Luck!
Have you tried:
belongs_to :author, :class_name => "User", :foreign_key => :user_id
From the Rails documentation:
By convention, Rails assumes that the column used to hold the foreign key on this model is the name of the association with the suffix _id added. The :foreign_key option lets you set the name of the foreign key directly
The example given in the docs is very similar to the one you have:
class Order < ActiveRecord::Base
belongs_to :customer, :class_name => "Patron", :foreign_key => "patron_id"
end
Let's say I have:
class Comment < ActiveRecord::Base
belongs_to :commentable, :polymorphic => true
end
class Article < ActiveRecord::Base
has_many :comments, :as => :commentable
end
class Photo < ActiveRecord::Base
has_many :comments, :as => :commentable
#...
end
now I want to find all comments on Jim's photo:
#jims_photo = Photo.where(:of => "Jim")
#photo_comments = Comment.where(:commentable => #jims_photo)
this seems to not work in rails (Rails 3). The generated query seems to not expand the polymorphic object into commentable_id and commentable_type fields:
SQLite3::SQLException: no such column: comments.commentable:
I'm new to ruby and rails so I might be using the paradigm incorrectly but my expectation was that rails automatically expands
:commentable => #jims_photo
to:
:commentable_id => #jims_photo.id, :commentable_type => #jims_photo.class.name
If you want to be really safe with:
:commentable_id => #jims_photo.id, :commentable_type => #jims_photo.class.name
Then I'd recommend replacing .class.name with .base_class (you don't actually need the name: to_s returns name and will be called automatically).
The reason for this is that when ActiveRecord saves the _type for a polymorphic association it'll use base_class to ensure it's not saving a class which itself is a polymorphic one.
If you play with store_full_sti_class you'll probably have to take even more precautions.
I highly recommend looking at Rails' STI code, here.
The guides for Rails are one of the best so I'd suggest you start reading about Polymorphic Associations
You class declarations looks OK and I'm assuming that you're migrations is as well. But just for the sake of it. Let's say it looks like this:
class CreateComment < ActiveRecord::Migration
def change
create_table :comments do |t|
t.string :name
t.references :commentable, :polymorphic => true
# this is the equivalent of
# t.integer :commentable_id
# t.string :commentable_type
t.timestamps
end
end
end
Not if you have a Article or Photo object and you want to get the comments for that object then Thilo's suggestion is right on. All you need to do is this: #jims_photo.comments
If, on the other hand, you have a an instance of the Comment model, you can get the parent like this: #comment.commentable. But if you want to get Jim's photo comments best to do it like that. Otherwise, you'd have to supply as arguments both the :commentable_id and commentable_type. I'm not aware of any finder that expands the polymorphic object into commentable_id and commentable_type fields for you.
But you can always create a class method for that:
def self.find_by_parent(parent)
where(:commentable_id => parent.id, :commentable_type => parent.class.name)
end
I'm trying out the new Rails gem http://activeadmin.info/ and it's working great! However I can't find any documentation on how to use it across associations. For example:
class Membership < ActiveRecord::Base
belongs_to :course
belongs_to :person
class Course < ActiveRecord::Base
has_many :memberships
has_many :people, :through => :memberships
class Person < ActiveRecord::Base
has_many :memberships
has_many :courses, :through => :memberships
The membership join table includes some extra data as well (ie: attendance). I'm trying to show the membership with both the course and student name - and allow filtering / sorting on those names. As far as I have found, Active Admin doesn't work across associations. Has anyone else been successful in doing that, or found another gem that does? Thanks so much!
ingredient.rb
class Ingredient < ActiveRecord::Base
has_and_belongs_to_many :products, :join_table => :ingredients_products
end
product.rb
class Product < ActiveRecord::Base
has_and_belongs_to_many :ingredients, :join_table => :ingredients_products
end
don't forget the migrations for the joining table (:id to false!)
class CreateProductsIngredients < ActiveRecord::Migration
def self.up
create_table :ingredients_products,:id => false do |t|
t.integer :product_id
t.integer :ingredient_id
t.timestamps
end
end
def self.down
drop_table :products_ingredients
end
end
Now define the form in you ActiveAdmin resource, override the default
ActiveAdmin.register Product do
form do |f|
f.inputs "Details" do
f.input :product_name
f.input :brand
f.input :ingredients # don't forget this one!
end
end
I've been playing with ActiveAdmin for a while now, here's how I managed to get associations to work in Indexes and Forms.
I've just guessed some of your model columns below. Also note, in the form. The 'person' section will show all the columns for editing, whereas the 'course' section will just show the specified column.
ActiveAdmin.register User do
index do
column :id
column :name
column :attendance
column :person do |membership|
membership.person.name
end
column :course do |membership|
membership.course.name
end
default_actions
end
form do |f|
f.inputs "Membership" do
f.input :name
f.input :created_at
f.input :updated_at
end
f.inputs :name => "Person", :for => :person do |person|
person.inputs
end
f.inputs :name => "Course", :for => :course do |course|
course.input :name
end
f.buttons
end
end
I haven't tested this, but you should be able to apply these ideas to your case. It's working for mine.
Update: I've just read your question again and noted that you're wanting to be able to sort on the association column. I've just checked my implementation and this indeed is not working. My answer may be useless to you but I'll leave it here anyway (might help someone else).
I've just started using this gem myself, and while I haven't gotten around to showing association information, here's how you create a form for associations:
form do |f|
f.inputs
f.has_many :associations do |association|
association.inputs
end
f.buttons
end
That will give you a basic form with scaffolding.
ingredient.rb
class Ingredient < ActiveRecord::Base
has_and_belongs_to_many :products, :join_table => :ingredients_products
end
product.rb
class Product < ActiveRecord::Base
attr_accessible ingredient_ids
has_and_belongs_to_many :ingredients, :join_table => :ingredients_products
end
migration_xxx.rb
class CreateProductsIngredients < ActiveRecord::Migration
def self.up
create_table :ingredients_products,:id => false do |t|
t.integer :product_id
t.integer :ingredient_id
t.timestamps
end
end
def self.down
drop_table :products_ingredients
end
end
products.rb
ActiveAdmin.register Product do
form do |f|
f.inputs "Details" do
f.input :product_name
f.input :brand
f.input :ingredients
end
end
...
end