rails organizing folders for service objects - ruby-on-rails

I'm trying yo create a service object to extract a few methods from the product.rb AR model, but for some reason I can't autoload the new TwitterShare class. When I hit up the console and try something like Product.last.twitter_share_text I get NameError: uninitialized constant Product::TwitterShare error.
What's going on in here? How should I organize my folders/files? Do I have to tell rails to autoload services? Here is the current code:
app/models/product.rb
class Product < ActiveRecord::Base
def twitter_share_text
TwitterShare.new(name: self.name, oneliner: self.oneliner).return_text
end
app/services/twitter_share.rb
class TwitterShare
attr_reader .........
def initialize....
end

You need to let rails know where it could possibly find TwitterShare.
Add the following to your application.rb
config.autoload_paths << "#{Rails.root}/app/services"
and then restart the console or server.
rails should now be able to locate twitter_share.rb and load TwitterShare correctly.
Refer to Autoloading and Reloading Constants for more info.

Related

Ruby - NameError: uninitialized constant. Using class from a different module

I have these 2 files in a large system, both are located in PackA
people.rb
module People
class HobbyValueObject
end
end
job.rb
module People
class Job
end
class CityValueObject
end
end
I am trying to use CityValueObject in a different module like this,
Module is in PackB
work.rb
module Profile
class Work
....
def calculateTaxes
...
a = People::CityValueObject....
end
end
end
But it's giving me an error saying,
NameError: uninitialized constant People::CityValueObject
Did you mean? People::HobbyValueObject
Why is not being able to fine CityValueObject but can find HobbyValueObject just fine?
How do I make it find the object that I am intending to use?
I am not explicitly declaring any requires or includes
I was able to resolve this by adding require at the top while using full path file name.
require './packs/people/app/public/people/job'

New model in Spree extension: uninitialized constant Spree::MyClass

I'm trying to create a new model in spree extension. I generated a model and it is in /spree_extension/app/models/my_class.rb:
module Spree
class MyClass < Spree::Base
belongs_to :product
end
end
But when I start my application, there is no Spree::MyClass, I get this error:
NameError: uninitialized constant Spree::MyClass
I tried moving my_class.rb to "spree" directory, but nothing helps.
Most probably, you need to put your class into:
/spree_extension/app/models/spree/my_class.rb
As rails is always expecting to find classes inside file with the same name, inside folder that has the module name.
The problem was in fact I created a table my_class.
Since I renamed it to spree_my_class, it works.

Uninitialized Constant in Rails Controller

I have the following in my controller:
class SurveysController < ApplicationController
def index
survey_provider = FluidSurveysProviders::SurveyProvider.new
contact_lists = survey_provider.get_lists()
#survey = Survey.new(contact_lists)
end
And I'm receiving this error:
NameError in SurveysController#index
uninitialized constant SurveysController::FluidSurveysProviders
Excuse my Rails noobiness, I'm sure I'm leaving out something important here. But it seems to me that I am trying to "initialize" the constant with this line:
survey_provider = FluidSurveysProviders::SurveyProvider.new
But that's the same line that's throwing an error because it's not initialized. Where should I be "initializing" the Provider?
Once you require fluid_surveys_providers (or similar) then do this:
include FluidSurveysProviders
Make sure SurveyProvider is wrapped with module FluidSurveysProviders. It may look like this
module FluidSurveysProviders
class SurveyProvider
...
end
end
if its an ActiveRecord object try this
class FluidSurveysProviders::SurveyProvider < ActiveRecord::Base
...
end
The SurveyProvider was not loaded correctly.
For a quick fix, move the class file into app directory, e.g. app/lib/survey_provider.rb. Then all code inside app will be auto-loaded by Rails.
Or make sure the path to class SurveyProvider is included in the autoload_path of Rails. In config/application.rb
config.autoload_paths += %W(#{config.root}/lib) # where lib is directory to survery_provider
If you use Rails 5, be careful that autoload is disabled in production environment. Check this link for more info.

How to refer to an instance of a class in Rails in a module?

I'm trying to dry up some code in my Rails application that allows to set a unique id when the object is creating using a filter. I have it in multiple locations and it seems like it should be in a module instead.
Right now I have something like this in each model.
def set_uid
self.uid = SecureRandom.uuid
end
I have included a new file in my /lib directory at the file uid_generator.rb and included that the module in each of the models.
//model
include UidGenerator
module UidGenerator
def set_uid
self.uid = SecureRandom.uuid
end
end
In my testing however, this yields the error
uninitialized constant MODELNAME::UidGenerator (NameError).
You just need to configure the autoload paths for your rails application. Here is something might be helpful. Best way to load module/class from lib folder in Rails 3?

How to extend a mountable engine's model inside another mountable engine with development environment reloading

Using Rails 3.2.2 and Ruby 1.9.2.
I have a rails mountable engine EngineA that declares a User class inheriting form ActiveRecord::Base. I have another engine EngineB that wants to inject functionality into EngineA::User. Right now what I have done is shown below:
Method 1:
#EngineA app/models/engine_a/user.rb
module EngineA
class User < ActiveRecord::Base
has_attached_file :avatar
has_many :somethings
end
end
#EngineB lib/engine_b/user.rb
module EngineB
module User
def self.extended obj
obj.class_eval do
has_many :something_elses
end
end
end
end
EngineA::User.extend EngineB::User
This gives me an uninitialized constant EngineA::User error. Even when I require that specific file I run into the problem of EngineA needing paperclip so that has_attached_file is understood. That road ended when I realized I would have to know and require the dependencies for EngineA inside EngineB.
Method 2:
I used the same code as before except I removed the last line EngineA::User.extend EngineB::User from the EngineB user.rb file. I then moved that call to an initializer inside EngineB.
#EngineB config/initializers/my_mixin.rb
EngineA::User.extend EngineB::User
This worked perfectly!!! Except in development mode when I would change code and the models would refresh. The only thing that was refreshed was the EngineA::User and not the mixin that I had put as an initializer. So once I changed code, I lost all of my extended functionality.
I'm not even positive this is the most 'efficient' way to do this... any help would be greatly appreciated. Thanks in advance.
According to the configuration documentation, you can use an ActionDispatch callback to load items. These callbacks will run when at every request if cache_classes is set to false, like in development mode.
Inside of your EngineB.rb file, you might try something like this:
if Rails.env.development?
ActionDispatch::Callbacks.to_prepare do
load "#{File.expand_path(File.dirname(__FILE__))}/../config/initializers/my_mixin.rb"
end
end

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