I've been jumping between design patterns, firstly trying polymorphic, now landing on STI. The main goal is to implement a Server > Host > Guest model where a Server has Hosts, Hosts have Guests and each able to have Posts. Although not the main purpose of the question any ideas in the design matter would be helpful as this is my first rails or ruby project.
What I have now is:
class Device
has_may :children, :class_name => "Device", :foreign_key => "parent_id"
belongs_to :parent, :class_name => "Device"
has_many :posts
end
class Server,Host,Guest < Device
end
STI is used because Server,Host,Guest basically have the same attributes.
I'm having trouble setting up the routes and controllers so I could view a Server's children which would be of type Host or to create a new Server's Host.
First, a good thing would be to add the following things, making everything easier to use for you :
class Device < ActiveRecord::Base
has_many :children, :class_name => "Device", :foreign_key => "parent_id"
has_many :servers, -> { where type: "Server" }, :class_name => "Device", :foreign_key => "parent_id"
has_many :hosts, -> { where type: "Host" }, :class_name => "Device", :foreign_key => "parent_id"
has_many :guests, -> { where type: "Guest" }, :class_name => "Device", :foreign_key => "parent_id"
belongs_to :parent, :class_name => "Device"
has_many :posts
end
With that, you will be able to do server.hosts, etc, which is quite convenient.
Then, you should move each subclass (Server, Host, Guest) to its own file due to Rails loading system. You can try to access the model Server in the console, you will get an undefined error. To fix it, you need to load the model Device, or simply move each subclass in a different file.
Finally, for the routing/controller part, I will advise you to read this post I wrote about common controller for STI resources : http://samurails.com/tutorial/single-table-inheritance-with-rails-4-part-2/.
Note that this is the second part, for more details check out the other articles.
Related
Hi I have a normal setup of Paperclip and S3 for image uploads in my application, this is the model I use for attachments:
class Picture < ActiveRecord::Base
belongs_to :ofert, dependent: :destroy
has_attached_file :image, :styles => { :medium => "300x300#", :thumb => "100x100>", :large => "600x400#", :morethumb => "50x50#", :ultrathumb => "25x25#" },
:default_url => "https://s3-sa-east-1.amazonaws.com/:s3_bucket/ofert_defaults/:style/brown_hat.jpg"
validates_attachment_content_type :image, :content_type => /\Aimage\/.*\Z/
validates_attachment_presence :image, :if => :isProduction?
validates_attachment_size :image, :less_than => 5.megabytes
#process_in_background :image, processing_image_url: 'https://s3-sa-east-1.amazonaws.com/:s3_bucket/ofert_defaults/:style/brown_hat.jpg'
end
The above works very well, however, when I try to destoy a picture:
picture.destroy
I get the following error: stack level too deep
but if instead I do the following:
picture.delete
It works, however the above only deletes the record but not the file uploaded to my S3 bucket, any idea?
It is a bug in rails. Read here
Using
belongs_to :ofert, dependent: :destroy
will cause a circular loop (assuming you have a similar line in the associated model 'Ofert' as well)
You can try replacing it with dependent :delete in one of these models or write after_destroy methods in both to manually destroy the associated model.
Read this discussion here on stackoverflow
I have a Has-Many:Through association , in which one side (AccessLevel ) is a defined model 'AccessLevel' , but the other side can be set for multiple resources
I defined a specific concern to be included in these models, and tried to use a polymorphic association
class AccessLevel < ActiveRecord::Base
has_many :allowed_activities
has_many :actionable, through: :allowed_activities
end
class AllowedActivity < ActiveRecord::Base
belongs_to :access_level
belongs_to :actionable, polymorphic: true
end
class <Model> < ActiveRecord::Base
include Authorizable
end
module Authorizable
extend ActiveSupport::Concern
included do
has_many :allowed_activities, as: :actionable
has_many :access_levels, through: :allowed_activities
end
end
is that a correct implementation or am I going to raise some unexpected collateral issues ?
thanks for feedback
It's not possible to use has_many: :through on polymorphic object
I need to specify the source_type of each object ( Sheet, ...
has_many :actionable_sheets, :through => :allowed_activities, :source => :actionable, :source_type => 'Sheet'
I have a Vehicles model where each vehicle has a make and model. When a user creates a vehicle, they can either select from currently available makes and models, or they can create a new make and model. Both make and model contain no extra data, so they are stored in the CommonLookup model I use for dynamic enumerations.
I want to limit model choices through ajax based on the currently selected make. To do this, I've created a blongs_to relationship on the CommonLookup model to itself; in other words, any record of that type can optionally reference a parent record of the same type in a many-to-one relationship.
The problem I'm running into is actually saving the relationship. My model code, which works for creating non-related make and model records, is as follows:
class Vehicle < ActiveRecord::Base
belongs_to :make, :class_name => "CommonLookup", :foreign_key => "make_id"
belongs_to :model, :class_name => "CommonLookup", :foreign_key => "model_id"
attr_accessor :new_make_name
attr_accessor :new_model_name
before_save :create_make_from_name, :create_model_from_name
def create_make_from_name
create_make(
:value => new_make_name
)
end
def create_model_from_name
create_model(
:value => new_model_name
)
end
end
This code successfully creates a vehicle with the associated new make and model, but the new make and model are not associated with each other as I need them to be. I need a many-models to one-make relationship that I can use to easily limit choices. To be clear, this question has nothing to do with the ajax part that is necessary for limiting choices; I'm focusing on the creation of the model instances themselves so that they are related, all from a single form.
I've attempted to set up code in the create_model_from_name callback but to no avail; there is no accessible reference to the object created in the first callback that could be used to set up the relationship. What I tried:
def create_model_from_name
create_model(
:value => new_model_name,
:parent => :make
)
end
But this didn't work. Any help would be greatly appreciated.
I solved this by combining the before_save callbacks and including a little more logic:
class Vehicle < ActiveRecord::Base
belongs_to :make, :class_name => "CommonLookup", :foreign_key => "make_id"
belongs_to :model, :class_name => "CommonLookup", :foreign_key => "model_id"
attr_accessor :new_make_name
attr_accessor :new_model_name
before_save :create_make_and_model_from_names
def create_make_and_model_from_names
if not new_model_name.blank?
if not new_make_name.blank?
create_model(
:value => new_model_name,
:parent => create_parent(
:value => new_make_name
)
)
else
create_model(
:value => new_model_name,
:parent => model
)
end
end
end
end
This met my requirements by setting up a way of creating new makes and creating and associating new models with both new makes and existing makes. The end result is that my ajax request is much easier to set up because I can easily locate the models associated with each make and place these in the options list.
I am using Rails 4.1.1, ruby 2.1, mongodb, mongoid as a wrapper, rails_admin for creating admin interfaces
I know that 'attr_accessible' no longer works for Rails4. So i have installed 'protected_attributes' gem. But still no success i am still getting warning in my console
[RailsAdmin] Could not load model Company, assuming model is non existing. (undefined method `attr_accessible' for Company:Class)
So, rails admin do not load the class Company because i have defined attr_accessible in the model. Here is my company model.
class Company
include Mongoid::Document
##employees_strength = {0 => '0-10', 1 => '11-50', 2 => '51-100', 3 => '101-500', 4 => '501-1000', 5 => '1000+', 6 => '5000+'}
field :name, type: String
field :website, type: String
field :domain_name, type: String
field :strength, type: Integer
has_many :employees
has_one :admin, :class_name => 'Employee', :dependent => :destroy, :inverse_of => :organization
#attr_accessible :name, :website, :domain_name, :strength#, :admin_attributes, :allow_destroy => true
attr_accessible :admin_attributes
accepts_nested_attributes_for :admin, :allow_destroy => true
end
Please any can body can help?
Thanks
Mongoid 4 (<= 4.0.2 at the time of writing) does not know about the ActiveModel::MassAssignmentSecurity module provided by protected_attributes gem.
As such you must include the behaviour in your models manually e.g.
class SomeDocument
include Mongoid::Document
include ActiveModel::MassAssignmentSecurity
field :some_field
attr_accessible :some_field
end
However, this gets tedious pretty quickly so a reasonable alternative is to include the module into the Mongoid::Document module before any of your models are defined.
module Mongoid
module Document
include ActiveModel::MassAssignmentSecurity
end
end
How to set the following association:
class Midatum < ActiveRecord::Base
# ..., diagn1, diagn2, diagn3
# sample data:
# ..., "0123", nil ,"0124"
# ..., "0123", nil ,"0124"
# ..., "0123", "1123", nil
belongs_to :icd9, :foreing_key => :diagn1
belongs_to :icd9, :foreing_key => :diagn2
belongs_to :icd9, :foreing_key => :diagn3
end
class icd9 < ActiveRecord::Base
# icd9, description
# sample data:(unique)
#"0123", "some text"
#"0124", "some other text"
#"1123", "description text"
#"1133", "description text"
has_many :midata, :foreing_key => :icd9, :primary_key => :icd9
end
This does not work. It may be obvious for someone but not for me. The database
is a legacy DB and readonly. I need to establish this assoc to able to work with the data.
This answer comes from a Rails expert and it does solve my problem. I am posting it in case someone else have the same problem.
belongs_to :icd9_a, :foreign_key => :diagn1, :class_name => "Icd9"
belongs_to :icd9_b, :foreign_key => :diagn2, :class_name => "Icd9"
belongs_to :icd9_c, :foreign_key => :diagn3, :class_name => "Icd9"
But that means you'll need to query the association using all three methods:
m = Midatum.first
m.icd9_a
m.icd9_b
m.icd9_c
In the same way, over in the Icd9 class you'll need three separate associations with unique names:
class Icd9 < ActiveRecord::Base
self.primary_key = :icd9
has_many :midata_a, :foreign_key => :diagn1, :class_name => "Midatum"
has_many :midata_b, :foreign_key => :diagn2, :class_name => "Midatum"
has_many :midata_c, :foreign_key => :diagn3, :class_name => "Midatum"
end
Note also that since the icd9 table doesn't have an 'id' column but uses the 'icd9' column as the primary key, you'll need to set it as I've done:
self.primary_key = :icd9