I have a file which looks like this
#app/services/account/authenticate/base.rb
module Account
module Authenticate
AuthenticateError = Class.new(StandardError)
class Base < ::Account::Base
def self.call(*attrs)
raise NotImplementedError
end
end
end
end
Now when I will run the code from rails c I have an error
> ::Account::Authenticate::AuthenticateError
=> NameError (uninitialized constant Account::Authenticate::AuthenticateError)
> ::Account::Authenticate.constants
=> [:Base, :ViaToken]
So rails doesn't see AuthenticateError class. But when I will create a nested class from this folder like
=> Account::Authenticate::ViaToken
> ::Account::Authenticate.constants
=> [:Base, :AuthenticateError, :ViaToken]
AuthenticateError class is now visible
> ::Account::Authenticate::AuthenticateError
=> Account::Authenticate::AuthenticateError
The solution for this problem is to create a separate file authenticate_error.rb which will work from the beginning but this solution is not ideal for me. Is there any solution to preload all classes or smth?
(Ruby 2.6 with Rails 6.0.0.rc2)
I experienced this same issue when deploying a Rails 6.0.2 application to an Ubuntu 18.04 server.
Unable to load application: Zeitwerk::NameError: expected file /home/deploy/myapp/app/models/concerns/designation.rb to define constant Designation, but didn't
I found out that the issue was with zeitwerk. Zeitwerk is the new code loader engine used in Rails 6. It’s meant to be the new default for all Rails 6+ projects replacing the old classic engine. Zeitwerk provides the features of code autoloading, eager loading, and reloading.
Here's how I solved it:
Navigate to the config/application.rb file on your project.
Add this line within your application module to switch to classic mode for autoloading:
config.autoloader = :classic
Here's an example:
module MyApp
class Application < Rails::Application
# Initialize configuration defaults for originally generated Rails version.
config.load_defaults 6.0
# Settings in config/environments/* take precedence over those specified here.
# Application configuration can go into files in config/initializers
# -- all .rb files in that directory are automatically loaded after loading
# the framework and any gems in your application.
config.autoloader = :classic
end
end
You can read up more on zeitwerk in this article: Understanding Zeitwerk in Rails 6
updating a Rails app from 5.2 to 6.0 and also hit the Zeitwerk bump!
If you want to continue to use the autoloading mode you're currently using, avoiding Zeitwerk, then add this line to your application.rb file (#PromisePreston answer and Rails doc)
config.autoloader = :classic
If you want to upgrade to Zeitwerk then a command to use is bin/rails zeitwerk:check (From this guide article).
Scenario we hit closest to this particular question was where we had a file within a subfolder like this:
#presenters/submission_files/base.rb
module Presenters
module SubmissionFiles
class Base < Showtime::Presenter
def method_call
#code_here
end
end
end
end
Removing an extra modules to have:
#presenters/submission_files/base.rb
module Presenters
class SubmissionFiles::Base < Showtime::Presenter
def method_call
#code_here
end
end
end
Then, when calling the method in other ruby files in the app use: Presenters::SubmissionFiles::Base.method_call
zeitwerk follow conventional file structure which is able to load your project's classes and modules on demand (autoloading) as long as you follow it's rule.
# service/account/authenticate/base.rb
module Account
module Authenticate
puts "load service ....."
AuthenticateError = Class.new(StandardError)
class Base
end
end
end
::Account::Authenticate::AuthenticateError # uninitialized constant
::Account::Authenticate::Base # load service ....
::Account::Authenticate::AuthenticateError # OK
as you can see, the first time you attempt to reach the constant AuthenticateError, the log load service ... does not show, that because you don't play zeitwerk rule:
whenever it gets a request to load the const ::Account::Authenticate::AuthenticateError, first it'll check and return if that constant already loaded, otherwise it'll look for the file /account/authenticate/authenticate_error.rb which corresponding to the constant ::Account::Authenticate::AuthenticateError to find that constant definition, but it could not find it.
on step 2, when you call ::Account::Authenticate::Base, it could find the file /account/authenticate/base.rb and load it, during this time, it's also load the constant AuthenticateError which is defined on that file, now we have the constant ::Account::Authenticate::AuthenticateError, and of course, it's OK on step 3.
now let try to play with the zeitwerk rule, i create a file /account/authenticate/authenticate_error.rb as below
# service/account/authenticate/authenticate_error.rb
module Account
module Authenticate
puts "load error ....."
AuthenticateError = Class.new(StandardError)
end
end
and try to attempt that constant at the step 1
$ spring stop
$ rails c
> ::Account::Authenticate::AuthenticateError
load error .....
=> Account::Authenticate::AuthenticateError
it worked since zeitwerk found the file account/authenticate/authenticate_error.rb. (note that the file name /____authenticate_error.rb still work)
my thought: i think you could work safely with the constant AuthenticateError inside the module ::Account::Authenticate, in case of you want to expose those error constants to outside, you could create file /account/authenticate/error.rb
# service/account/authenticate/error.rb
module Account
module Authenticate
module Error
AuthenticateError = Class.new(StandardError)
end
end
end
then you could access ::Account::Authenticate::Error::AuthenticateError, in my opinion, it even clearer than put AuthenticateError inside base.rb.
I was able to fix it by not trying to fight Rails 6. Zeitwerk autoloads certain expected folders, which includes app/models, app/controllers, app/helpers and others.
I created a folder app/helpers and moved my services folder into it.
That's it!
Related
In my Rails project, I want to add services directory in app folder and include some service objects.
So let's say I want to add app/services/foo/test.rb which looks like:
module Services
module Foo
class Test
end
end
end
In my config/application.rb I added:
config.paths.add File.join('app', 'services'), glob: File.join('**', '*.rb')
config.autoload_paths += Dir[Rails.root.join('app', 'services', '*')]
However when I try to load the files in console it doesn't work:
⇒ rails c
Loading development environment (Rails 4.1.4)
[1] pry(main)> Services::Foo::Test
NameError: uninitialized constant Services
Any help how can I solve this issue?
After add new dir, reload spring
spring stop
First of all, the code under app folder will be loaded without any config.
I think the problem was the folder structure doesn't match with your class definition.
So this config will work:
app/services/foo/test.rb
module Foo
class Test
end
end
My clue is, for example we have app/controllers/api/v1/users_controllers.rb and the class constant will be Api::V1::UsersController, not Controllers::Api::V1::UsersController
Update
Conventionally, we usually use FooServices instead of Foo, it is clearer, for example:
app/services/foo_services/bar_parser.rb
module FooServices
class BarParser
# Do stuff
end
end
So we understand that every class inside foo_services folder is a service which related to Foo
My problem was because of Rails naming conventions, I suppose. I just renamed class to not use module Services and it worked.
This is a tricky one to explain. I have a module in another module namespace like so:
# app/models/points/calculator.rb
module Points
module Calculator
def self.included(base)
base.send(:include, CommonMethods)
base.send(:include, "Points::Calculator::#{base}Methods".constantize)
end
end
end
So then in other classes all I need to do is:
class User
include Points::Calculator
end
I've specified this directory in application.rb to be autoloadable...(even though i think rails recurses through models...)
config.autoload_paths += Dir[ Rails.root.join('app', 'models', "points") ]
In development env, everything works fine. When running tests(and production env), I get the following error:
Unable to autoload constant Points::Calculator, expected /Users/pete/work/recognize/app/models/points/calculator.rb to define it (LoadError)
I actually followed the advice here to fix the problem: Stop Rails from unloading a module in development mode by explicitly requiring calculator.rb in application.rb.
However, why is this happening??
I stuck some debug output in ActiveSupport's dependencies.rb file and noticed that this file is being required twice. The first time its required I can see that the constant is indeed loaded.
But the 2nd time its required the constant has been unloaded as far as Rails can tell, but when the actual require is called, ruby returns false because ruby knows its already required it. Then Rails throws the "unable to autoload constant" error because the constant still isn't present and ruby didn't "re-require" the file.
Can anyone shed light on why this might be happening?
Rails augments the constant lookup mechanism of ruby.
Constant lookup in Ruby:
Similar to method missing, a Module#constant-missing is invoked when a reference to a constant fails to be resolved. When we refer to a constant in a given lexical scope, that constant is searched for in:
Each entry in Module.nesting
Each entry in Module.nesting.first.ancestors
Each entry in Object.ancestors if Module.nesting.first is nil or a module.
When we refer to a constant, Ruby first attempts to find it according to this built-in lookup rules.
When ruby fails to find... rails kicks in, and using its own lookup convention and its knowledge about which constants have already been loaded (by ruby), Rails overrides Module#const_missing to load missing constants without the need for explicit require calls by the programmer.
Its own lookup convention?
Contrasting Ruby’s autoload (which requires the location of each autoloaded constant to be specified in advance) rails following a convention that maps constants to file names.
Points::Calculator # =>points/calculator.rb
Now for the constant Points::Calculator, rails searches this file path (ie 'points/calculator.rb') within the autoload paths, defined by the autoload_paths configuration.
In this case, rails searched for file path points/calculator in its autoloaded paths, but fails to find file and hence this error/warning is shown.
This answer is an abstract from this Urbanautomation blog.
Edit:
I wrote a blog about Zeitwerk, the new code reloader in Rails. Check it out at -> https://blog.bigbinary.com/2019/10/08/rails-6-introduces-new-code-loader-called-zeitwerk.html
If someone is having this issue in rails 6 which has zeitwerk autoloader,
Change ruby constant lookup back to classic in your application.rb
# config/application.rb
#...
config.autoloader = :classic
#...
Read more details here Rails Official Guides
Calculator should be a class to be autoloaded correctly
module Points
class Calculator
...
end
end
I'm developing a gem/engine. The way I do this is by bundling it in a test RailsApp from source:
# Gemfile
gem 'my-engine', path: '../local/path/to/gem'
This works fine so far.
But, after I change a file in my gem (add a space or a break for example) the Engine is unloaded. Causing the following error:
uninitialized constant My::Engine
This error is thrown by the file that does the first call to My::Engine. ( I need to call that to get the root: My::Engine.root ) If I delete that line, there are no error thrown, but just an empty page is rendered, and this is happening because all my SQL's change and no content is loaded from the database. I think this is because the files in the lib dir are unloaded, because in these files I dynamically create active-record models..
I already checked out the autoload_paths and watchable_dirs:
# engine.rb
module My
class Engine < Rails::Engine
engine_name 'my-engine'
initializer "my-engine.load_config" do |app|
app.config.autoload_paths += %W(#{Engine.root}/lib)
app.config.watchable_dirs["#{Engine.root}/lib"] = [:rb]
end
end
end
I'm not sure if I'm implementing these the right way, but they don't seem to solve my problems the way I'm using them.
I think you may need to require 'my/engine' before calling My::Engine.root, or change the order of your requires so that 'my/engine' is required prior to the file that makes a call to My::Engine.
I have a bunch of custom classes in my Rails 3.2 app in lib folder: i.e. extending ActiveRecord, etc. It all works fine.
However I'm trying to add a couple of custom methods to FileUtils, i.e.
module FileUtils
def last_modified_file(path='.')
# blah ...
end
end
I put it in lib/file_utils.rb
In my application.rb I have
config.autoload_paths += %W(#{config.root}/lib)
My other custom classed are loaded but not the module.
I read (Best way to load module/class from lib folder in Rails 3? ) that I'm supposed to define a class inside module in order for Rails to pick it up and according to FileUtils.class - it should be Object < BasicObject.
So I tried
module FileUtils
class Object
def last_modified_file(path='.')
# blah ...
end
end
end
But that doesn't work either.
However when I fire up irb and just paste my code which effectivly puts my new code inside object and reinclude my module - it works fine.
Whaat amd I missing here?
Your patch is never going to be loaded because autoload is only invoked when Rails can't find a constant. Since the FileUtils constant already exists, the autoloader is never called, and your file is never loaded.
Simply require it from an initializer.
require File.join(Rails.root, "lib/file_utils.rb")
I have to change my rail application's default log path because of my company's internal software deployment process: basically my rails app ends up on a read-only location, and I need the log files written in a directory "made for this".
With Rails 2.x we used to add some black magic in our FCGI script to force that in when deployed on prod. hosts:
class Rails::Configuration
def default_log_path
File.join(ENV['SOME_ENVIRONMENT_VAR'], "var/output/logs/rails.log")
end
end
However, Configuration isn't a class anymore in Rails 2.3 (it's a module), and it appears to me there isn't any default_log_path involved there anymore as well...
You just need define your logger
config.logger = ActiveSupport::BufferedLogger.new(File.join(ENV['SOME_ENVIRONMENT_VAR'], "var/output/logs/rails.log"))
This trick works with Rails 2 too. And you can define by environment where you really want your log file.
The config.log_path setting has been deprecated - the recommended solution is now:
config.paths.log = "/some/path/#{Rails.env}.log"
As of Rails 3.2.3, looks like the log pathname is also defined in Rails::Rack::LogTailer#initialize, and that comes from Rails::Server#log_path.
LOG_PATH = "log/mylog.log"
require 'rails/commands/server'
module Rails
class Server
def log_path
LOG_PATH
end
end
end
class Application < Rails::Application
...
config.paths['log'] = LOG_PATH
...
end