I am struggling to use CanCan with my polymorphic associations. It is breaking down when I try and load the polymorphic objects in my controller.
class Trip < ActiveRecord::Base
has_many :images, as: :viewable
end
class Image < ActiveRecord::Base
belongs_to :viewable, polymorphic: true
end
Now I have a controller that deals specifically with images assigned to a trip.
class TripImagesController < ApplicationController
load_and_authorize_resource :trip
load_and_authorize_resource :image, through: :trip
def index
end
end
However, when I hit this index action I get the following error:
Couldn't find Image with id= [WHERE "images"."viewable_id" = $1 AND "images"."viewable_type" = $2]
I can see the query being executed in the Rails logs:
SELECT "images".* FROM "images" WHERE "images"."viewable_id" = $1 AND "images"."viewable_type" = $2 AND "images"."id" = $3 LIMIT 1 [["viewable_id", 1], ["viewable_type", "Trip"], ["id", ""]]
So the select statement looks good, except that it's trying to find only a single image (even though I'm in an index action). It's specifying an image id (which obviously does not exist in the route params) and it's also limiting the result to a single row.
This is using Rails 4.0.2 and CanCan 1.6.10. What am I missing here?
Related
I'm at my wit's end. I upgraded to Rails 4.2.10, and everything is terrible.
Here is the relevant part of /models/product.rb
class Product < ActiveRecord::Base
delegate_attributes :price, :is_master, :to => :master
And here is /models/variant.rb:
class Variant < ActiveRecord::Base
belongs_to :product
The variants table has fields for "price" and "is_master". Products table does not.
It used to be the case that one could access Product.price and it would get/set the price for the master variant (there's really only one variant per product, the way things are currently set up).
Now it complains that:
NoMethodError: undefined method `price=' for #<Product:0x0000000d63b980>
It's true. There's no method called price=. But why wasn't this an issue before, and what on earth should I put in that method if I create it?
Here's the code to generate a product in db/seeds.rb:
product = Product.create!({
name: "Product_#{i}",
description: Faker::Lorem.sentence,
store_id: u.store.id,
master_attributes: {
listing_folder_id: uuids[i],
version_folder_id: uuids[i]
}
})
product.price = 10
product.save!
end
delegate_attributes isn't a Rails method and looks like it comes from a gem (or gems) that aren't actively maintained?
If there's a new version of whatever gem you're using that might help, because the short answer is that part of the "delegating" of an attribute would involve getting and setting the attribute, so it would generate #price= for you.
If you want to define it yourself, this should do it (within your Product class):
def price=(*args)
master.price=(*args)
end
or if you want to be more explicit:
def price=(amount)
master.price = amount
end
In my application I have models Post & Slides & I have:
class Post < ActiveRecord::Base
has_many :slides, inverse_of: :post
accepts_nested_attributes_for :slides, reject_if: :all_blank, allow_destroy: true
Everything works fine, only thing I need (because of how my application will work), is when a slide is created, I need to assign it to current_user or user that is creating the record.
I already have user_id in my slides table and:
class User < ActiveRecord::Base
has_many :posts
has_many :slide
end
class Slide < ActiveRecord::Base
belongs_to :user
belongs_to :post
end
My PostsController looks like this:
def new
#post = current_user.posts.build
// This is for adding a slide without user needing to click on link_to_add_association when they enter new page/action
#post.slides.build
end
def create
#post = current_user.posts.build(post_params)
respond_to do |format|
if #post.save
format.html { redirect_to #post, notice: 'Was successfully created.' }
else
format.html { render :new }
end
end
end
Any help is appreciated!
There are two ways to accomplish this:
First option: when saving the slide, fill in the user-id, but this will get pretty messy quickly. You either do it in the model in a before_save, but how do you know the current-user-id? Or do it in the controller and change the user-id if not set before saving/after saving.
There is, however, an easier option :) Using the :wrap_object option of the link_to_add_association (see doc) you can prefill the user_id in the form! So something like:
= link_to_add_association ('add slide', #form_obj, :slides,
wrap_object: Proc.new {|slide| slide.user_id = current_user.id; slide })
To be completely correct, you would also have to change your new method as follows
#post.slides.build(user_id: current_user.id)
Then of course, we have to add the user_id to the form, as a hidden field, so it is sent back to the controller, and do not forget to fix your strong parameters clause to allow setting the user_id as well :)
When I'm looking at this I see three ways to go about it, but since you're on cocoon already, I would drop the connection between user & slides - as it kind of violates good database practices (until you hit a point where you page is so popular you have to optimize of course, but that would be done differently).
You are using cocoon, but you're not utilizing the nesting of the relationship fully yet ...
The best practice would be to have cocoon's nesting create both & instead of trying to assign to current_user you call something like:
#slides = current_user.posts.find_first(param[:id]).slides
The #slides saves all the results, the .Post.find(param[:id]) finds a specific post for current_user.
Note: this is not the most optimized way & I haven't tested this, but it shows you the format of one way you can think about the relationships. You will need to hit rails console and run some tests like ...
(rails console)> #user = User.first
Next we test that there are posts available, as it's frustrating to test blanks & not get the results ...
(rails console)> #posts = #user.posts
Then we use the find method & I'm going to use Post.first just to get a working id, you can easily put "1" or any number you know is valid ...
(rails console)> #post = #posts.find(Post.first)
Finally, we go with either all slides to make sure its a valid dataset
(rails console)> #post.slides
If you want a specific slide later & have a has_many relationship just tag that find method on the .slides after.
Also one last thing - when you state earlier in there you need the current_user to be related, you can use an entry in your model.rb to create a method or a scope to get the data & allow you to link it to the current_user more easily & even drop some directed SQL query with the .where method to pull that information up if performance is an issue.
I spotted a second optimization in there ... if everything really is working - don't worry about this!
And don't forget about the strong_parameters nesting to do this fully ... Strong Param white listing
Basic format ... `.permit(:id, :something, slide_attributes: [:id, :name, :whatever, :_destroy])
I’m using Rails 4.2.3. I have these two models
class Address < ActiveRecord::Base
…
has_one :user
and
class User < ActiveRecord::Base
belongs_to :address
default_scope includes(:address)
I want to auto-load my parent association when I load my “MyObject” but I’m getting this error on the “default_scope” line …
Support for calling #default_scope without a block is removed. For example instead of `default_scope where(color: 'red')`, please use `default_scope { where(color: 'red') }`. (Alternatively you can just redefine self.default_scope.)
How do I adjust my “default_scope” line to auto-load my parent association?
You are missing block in your line, Change it like this:
default_scope { includes(:address) }
I am connecting to one of my company's SQL Server databases, and trying to set up ActiveRecord so I can treat them just the same as Rails objects.
I have these two models:
class Change < ActiveRecord::Base
belongs_to :affected_contact, class_name: "Contact"
end
class Contact
# Contact's primary key is a binary UUID; I can't change this
end
I am trying to get the affected contact of one particular change. Normally, this would be a simple case, but:
Change.first.affected_contact
Change Load (52.6ms) EXEC sp_executesql N'SELECT TOP (1) [chg].* FROM [chg] ORDER BY [chg].[id] ASC'
Contact Load (28.0ms) EXEC sp_executesql N'SELECT TOP (1) [ca_contact].* FROM [ca_contact] WHERE [ca_contact].[contact_uuid] = #0', N'#0 binary', #0 = 0xfcf9a8ac6381aa4386c9b10ee382e10b [["contact_uuid", "<16 bytes of binary data>"]]
=> nil
... that's not what I want! And yet, if I eager-load the join first, it works:
Change.eager_load(:affected_contact).first.affected_contact
SQL (34.4ms) EXEC sp_executesql N'SELECT TOP (1) holy_crap_theres_a_lot_of_columns FROM [chg] LEFT OUTER JOIN [ca_contact] ON [ca_contact].[contact_uuid] = [chg].[affected_contact] ORDER BY [chg].[id] ASC'
=> #<Contact contact_uuid: "\xFC\xF9\xA8\xACc\x81\xAAC\x86\xC9\xB1\x0E\xE3\x82\xE1\v", ... >
In fact, if I force the matching to happen in the JOIN clause in any way, it will work, but belongs_to seems to use the WHERE clause instead, and nil is the best response I can get (a lot of the time, there are conversion errors between the string and its binary type).
Is there a way to ensure eager-loading through the JOIN clause happens by default on the belongs_to association?
I found that #find_by_contact_uuid (contact_uuid being the primary key) worked, where #find didn't, for some reason. That led to this being implemented.
I have ended up essentially rewriting the association methods that Active Record supplies:
module AssociationMethods
def self.included(base)
base.reflect_on_all_associations(:belong_to).each do |a|
define_method a.name do
# #find_by_<uuid_pk> seems to work where #find doesn't
a.klass.send "find_by_#{a.association_primary_key}", self[a.foreign_key]
end
end
base.reflect_on_all_associations(:has_many).each do |a|
define_method a.name do
a.klass.where(a.foreign_key => self.send(a.association_primary_key))
end
end
end
end
class Contact
has_many :changes, foreign_key: :affected_contact_id
include AssociationMethods # include *after* all associations are defined
end
class Change
belongs_to :affected_contact, class_name: 'Contact'
include AssociationMethods
end
It doesn't cover everything that Active Record supplies when setting up the associations, but it seems to do the trick.
Using includes should resolve your problem. This is because includes will preload or eager_load depending on your other conditions.
read more here
I'm upgrading a Rails application from v3.2.13 to v4.1.5. Consider the following models.
class Camera::Clip < ActiveRecord::Base
belongs_to :camera
def self.cleanup(opts)
# blah blah method stuff
system_clips = Camera::Clip.includes(:camera).where(['cameras.control_system_id = ?', opts[:control_system_id]])
# In Rails 4, raises Mysql2::Error: Unknown column 'cameras.control_system_id'
end
end
class Camera < ActiveRecord::Base
belongs_to :control_system
has_many :clips, dependent: :destroy
# rest of class
end
I can get the method to function as it had originally by changing the :includes call to :joins, but why is that necessary? I thought :includes used a LEFT OUTER JOIN call on the database to combine the resources?
This may have been lost on me in Release Notes documentation, but a second step is needed to tell the where clause what I mean by 'cameras'.
This documentation pointed me to the :references method.
Swapping out the line for
Camera::Clip.includes(:camera).where('cameras.control_system_id = 13').references(:camera)
shows the exact same output in the Rails console as my environment running in Rails 3.2.13, with no error! Great success.