I have created a simple class under the models folder like so:
class CaffeineShops
def initialize
end
end
When I run rails console and try CaffeineShops.new(), I get a message: "NoMethodError: undefined method 'new' for CaffeineShops::Module"
I am using Rails 4.1.
Any ideas why I am getting that error?
You cannot name a model the same name as the application itself. When you run rails g caffeine_shops this creates a module named CaffeineShops which will power your application.
The module is utilized in many files including
config\application.rb
config\environment.rb
config\environments\development.rb
config\environments\production.rb
config\environments\test.rb
config\initializers\secret_token.rb
config\initializers\session_store.rb
config\routes.rb
config.ru *actually starts the application on Rack-based servers
Rakefile *loads rake tasks for the application
When you then try to name a class the same name it creates ambiguity in the rails application so your code is assuming you mean the module CaffeineShops not the class CaffeineShops.
If you were to actually use a generator to define this model rails would make it very clear there was a problem with this e.g.
rails g caffeine_shops
cd caffeine_shops
rails g model caffeine_shops
#=>The name 'CaffeineShops' is either already used in your application or reserved
by Ruby on Rails. Please choose an alternative and run this generator again.
Related
I ran following code in rails console:
ApplicationRecord.descendants.count # It returns only 1
Even there are many inheriting classes from the "ApplicationRecord" are available inside project_root/app/models/ in rails 5.2.4.
The models won't be loaded when you open the console, you can use #eager_load! after opening the rails console to change that:
Rails.application.eager_load!
I'm building a platform in Rails that will act as a basis for a few other Rails applications. Ideally I would like this to be a shared engine, on which the other concrete applications can build.
It would be nice if the applications could extend the base classes that the engine provides. AFAIK this can be done using monkey patching, but that feels 'hacky' to me.
I stumbled onto what looked like the solution, which was to just create 'mirror' classes in the main Rails app, which extend those of the engine:
# SharedEngine/models/shared_engine/post.rb
module SharedEngine
class Post < ActiveRecord::Base
def hello
"Hello"
end
end
end
# App/models/shared_engine/post.rb
require SharedEngine::Engine.root.join('app', 'models', 'shared_engine', 'post')
class Post < SharedEngine::Post
def hello
super + " world"
end
end
However, it looks like there are some autoloading problems. After server startup, it prints "Hello". Then after I save the app model, it says "Hello world".
The Rails engine guide suggests putting shared code into concerns. Is there any other way to get this working cleanly without having to create concerns for every class?
Since you need to create a basis for a few Rails apps to reduce boilerplate i suggest having a look a Rails Application Templates. Using templates you may provide all the necessary scaffolding without monkey-patching any class.
i use framwork Espresso with Enginery generator (Ruby gems). I create new project, and not understand how work this application. I will work with Espresso. Explain me struct Expresso Application, please.
I can run this apllication: rackup config.ru
I can edit controllers, but i not understand depending between ruby scripts in this project.
i run projects, but why this work it?
config.ru
require File.expand_path('../base/boot', __FILE__)
puts App.urlmap
run App
in project not /base/boot directory.
requiring '../base/boot' will actually load dependencies, controllers, models etc. and build the application.
The application are stored under App constant, so you can access it from different files:
https://github.com/espresso/enginery/blob/master/app/base/base/boot.rb#L9
puts App.urlmap will display all the routes to be served by app.
And run App will start your app.
You can also start app by ruby app.rb, then you do not need to pass server/port at startup.
Instead you'll set them in config/config.yml, like this:
development:
server: Thin
port: 5252
The config.ru file looks quite normal for a rack start-up file. You would start the application from the project folder, with a command like:
rackup -p 8080
The following line:
require File.expand_path('../base/boot', __FILE__)
will load in the ../base/boot file (similar to require_relative, but also works with older Ruby e.g. 1.8.7), which I would guess requires the dependencies where App is defined. The class or module App will implement a call method. To start the server, the rack host calls App.new (which is called due to run App) and then on each request it will call .call( env ) on the resulting object (the object doesn't have to be an App object, but in simpler frameworks it will be).
The variable env contains all the details of the request and the rack environment that can be inspected to fetch details of the current path, cookies, query params etc. Typically access to this data is abstracted through Sinatra and Espresso helper methods that you will use.
The Sinatra and Espresso helper methods look like they are doing magic declarations, but they are just normal methods. Usually they do some calculation and then stash a code block/lambda for rack to call later. Sinatra's get is like this . . . it isn't true declarative code. Instead, when the controller is parsed, it just takes the code block and tells the application object to call it (later) when the path matches.
I am following this tutorial to add messaging functionality between the users in my rails app, but got an error in my User model.
class User < ActiveRecord::Base
has_mailbox
end
This gives me the following error:
undefined local variable or method `has_mailbox' for #<Class:0xb60f6f84>
Any ideas?
I've checked this gem, try to run
rails g has_mailbox:install
when you install any gem in rails app, the good idea is to check generators available
rails g //list of available generators
I created an engine inside an app that depends on an external gem: Spree.
And I did my best to set RSpec within that engine following this guide.
When I try testing a controller with some integrated testing:
tests_spec.rb:
require 'spec_helper'
describe "Tests" do
describe "GET /tests" do
it "works! (now write some real specs)" do
# Run the generator again with the --webrat flag if you want to use webrat methods/matchers
get tests_path
response.status.should be(200)
end
end
end
I get an error in the dummy app's environment.rb file, that says that following command couldn't be run:
# Initialize the rails application
Dummy::Application.initialize!
Because my controller is using Admin::ResourceController as an extension which is declared within the external Spree gem. As if rspec is unable to read that class from gemfile of the main app (the one that contains the engine plugin).
Can someone please shed some light on that?