I have 2 classes
MyController which is under app/controllers/api
MyManager which is under libs/managers
I am trying to use this manager class from my controller and I'm getting the following error.
Uninitialized constant API::MyController::MyManager
How do I reference and use MyManager class from MyController class?
Controller
class API::MyController < API::BaseController
before_action :setup
def something
#myManager.doSomething
end
def setup
# Exception is thrown here
#myManager = MyManager.new
end
end
Manager
class MyManager
def doSomething
puts('something')
end
end
Make sure you autoloaded the lib/managers directory:
# in config/application.rb
config.autoload_paths += %W(#{config.root}/lib/managers)
If MyManager is a Class (not a module) then you can just call MyManager.new without any problem.
Also just a note. In Rails 4 there are a couple of 'concerns' directories added under app/controllers and app/models (app/controllers/concerns and app/models/concerns). Any files under these directories will be autoloaded. By standards, only model related concerns (be it modules or classes) will be placed under app/models/concerns (same applies for controller related concerns).
This has to do with the way rails loads modules, take a look at this
I think what you want is to make sure your autoloading the lib directory and then call ::MyManager.method since its trying to get the module from the Controller context.
::Module indicates the absolute module.
Related
I am currently creating a Rails engine. So far the engine has a few new routes and a few new controllers. The routes work fine, as I was able to mount them adding the following to config/routes.rb:
mount MyEngine::Engine => '/'
The problem comes with the controllers. When trying to access the actions I have defined, I get:
uninitialized constant MyEngine::ApplicationController
I am a bit surprised, as the documentation suggests that everything inside app/ is autoloaded from the engine. I have even tried to explicitly load the controllers in engine.rb, to no avail:
module MyEngine
class Engine < ::Rails::Engine
isolate_namespace MyEngine
Dir["#{config.root}/app/controllers/**/"].each do |path|
config.eager_load_paths << path
end
end
end
I'm confused. Aren't the contents of app/controllers/ supposed to be autoloaded by the application from the engine?
It looks like your engine's controller is trying to reference an ApplicationController inside your engine, when you might have wanted to inherit from the main application's ApplicationController (correct me if I'm wrong).
I don't know how the controller code in your engine looks like (feel free the share if I am not on the right track), but I assume it looks something like this
module MyEngine
class MyController < ApplicationController
end
end
In this scenario, it requires you to also have defined MyEngine::ApplicationController somewhere, and based on the error message, I assume this controller does not exist.
To solve this, you could either define the engine specific ApplicationController, or you can specify that you want to inherit from the root controller, like this:
module MyEngine
class MyController < ::ApplicationController
end
end
If you later want to be even more flexible in your engine, it is often left to an initializer configuration option to set which controller to inherit from (see example from Devise).
module MyEngine
class MyController < MyEngine.parent_controller.constantize
end
end
I'd like to make a function current_order_week that would be available globally throughout my app and could be called similarly to something like current_user. I don't want to have to include it in a specific model / controller, I just want it available everywhere.
I've modified my /lib folder to include a lib_extensions.rb file and added to that file:
class Object
def current_order_week
end
end
I've modified my application.rb to include:
config.autoload_paths << Rails.root.join('lib')
config.eager_load_paths << Rails.root.join('lib')
But when I attempt to call current_order_week from the console or from a test, I still see:
NameError: undefined local variable or method 'current_order_week'
for main:Object
What else do I need to do?
You should add this function in the application_helper.rb file. All controllers extend from ApplicationController and ApplicationController includes the ApplicationHelper.
module ApplicationHelper
def current_order_week
end
end
This will be available to use in views and controllers
Monkey-patching core classes like Object is usually not a good idea, this may interfere with some gems etc. and in general can lead to painful debugging in the future.
If you absolutely want to do this - autoloading will not pick up Object from lib, because it is already defined. Create an initializer in config/initializers, then it will be loaded, but it will not reload on code changes.
But better way is including such code in ApplicationHelper, ApplicationRecord and ApplicationController
autoload_paths and eager_load_paths don't include modules, they only require files in which modules are defined. To use current_order_week you need to specify the name of the module:
module Foo
def current_order_week
.
.
.
end
end
Foo.current_order_week()
In order to use current_order_week without prepending the name of the module to it, you need to include Foo inside your controllers and models:
class ApplicationController < ActionController::Base
include Foo
def some_action
current_order_week()
end
end
class ApplicationRecord < ActiveRecord::Base
include Foo
end
In Rails, how do you use a specific method from a module. For eg,
# ./app/controllers/my_controller.rb
class MyController < ApplicationController
include MyModule
def action
MyModule.a_method
end
private
def a_method
...
end
end
# ------------------------------------------------ #
# ./app/helpers/my_module.rb
module MyModule
def a_method
...
end
end
MyController includes MyModule. And in action ,I want to use MyModule.a_method (Please note I also have a private a_method in MyController and I don't want to use this.)
Things I've tried :
1) Defining the method in the module as self.
def self.a_method
end
2) Using the :: notation in controller (MyModule::a_method)
The error that I keep getting is
Undefined method:a_method for MyModule:module
For now, I've resorted to using a different name for the modules method. But I'd like to know how to namespace the function with either the Module:: or Module. notation
[UPDATE - 11/24/2014]
adding file structure in code, since Rails heavily relies on convention.
So I am not really sure what you are trying to accomplish with your module but a quick solution to get it working is below.
Move my_module.rb out of helpers and into lib/my_module.rb. The helpers directory is for methods that you use in your views. The convention is to utilize helpers that are namespaced after their respective controller or the application_helper.rb for global methods for your views. Not sure if that's what you are trying to accomplish with your module but wanted to throw that out there.
Create an initializer (you can all it whatever) in config/initializers/custom_modules.rb and add require 'my_module'
Update the a_method back to be self.a_method
You can now call MyModule.a_method in your app
Don't forget to restart your server for changes to lib/my_module.rb to take effect.
Also, a lot of people reference this post by Yehuda Katz as guidance on where to store code for your app. Thought it might be a helpful reference.
if you include MyModule into MyController, all the "instance methods" of the first will be mixed-in into the 2nd.
So if you only want to call MyModule.a_method, no need to include your module.
Then you'd want to require (or better autoload) your module before using it. To do so place it in controllers/concerns/my_module.rb, rails (4 at least) should autoload it, otherwise require its file in an intializer
# my_module.rb
module MyModule
def self.a_method
...
end
end
should work, but doing
# my_module.rb
module MyModule
extend self
def a_method
...
end
end
is more clean to me. You'd like to have a look to rails active support concern to understand the "rails way" on this topic.
In a file called foo.rb in my /lib/ directory it reads:
module Foo
def some_method
#text_1 = "Hello!"
end
end
How can I get the results of this method to show up in a View?
I've seen that I need to include the following line in the /config/application.rb file:
config.autoload_paths += %W(#{config.root}/lib
However, I do not completely understand how to pass a variable from a module in a file saved in the /lib/ directory - to show up in a View. I appreciate any advice.
In order to get that value to show up in the view, you'll need to understand how modules are used in Ruby. Typically modules are mixed into other classes either by including or extending them. This would then make that method available to another class which could then be referenced in the view. In your case you might want to include it so it becomes available to instances of whatever class you put it in. Say you have an ActiveRecord model called MyClass and you include Foo. You can then call my_method on instances of that model as demonstrated below:
class MyClass < ActiveRecord::Base
include Foo
end
In your controller:
class MyController
def new
#my_class = MyClass.new
end
end
In your view:
#my_class.some_method
Having said all that, it seems like there might be a better way to do whatever it is you're trying to do :)
Yes.I agree with
Beerlington.
You can do it in an other way,
It is not mandatory to add config.autoload_paths += %W(#{config.root}/lib to application file.Because by default the files which are located in /lib directory won't be executed at first when we run an application using rails s.
In order to make those files to be loaded,we need to include that line in application.rb.
Otherwise,we can directly write it as below,
In model,
require 'Filename'
class MyClass < ActiveRecord::Base
include Foo
end
In controller,
require 'foobar'
class BuyerController < ApplicationController
include Foobar
end
In foobar.rb,
module Foobar
def Foobar.foobar
"Hello world!"
end
end
In view,
<%= Foobar.foobar %> (You can directly call the method by using Modulenmae.Methodname)
I am writing a custom wrapper for open_flash_chart plugin. It's placed in /lib and load it as a module in ApplicationController.
However, I have either a problem with the Class hierarchy or some other problem.
From any controller I can access open_flash_chart functions as OpenFlashChart, Line etc.
However, in a class in a /lib module, it doesnt work!
Any ideas?
There are two ways that files get loaded in Rails:
It is registered in the autoload process, and you reference a constant that corresponds to the file name. For instance, if you have app/controllers/pages_controller.rb and reference PagesController, app/controllers/pages_controller.rb will automatically be loaded. This happens for a preset list of directories in the load path. This is a feature of Rails, and is not part of the normal Ruby load process.
Files are explicitly required. If a file is required, Ruby looks through the entire list of paths in your load paths, and find the first case where the file you required is in the load path. You can see the entire load path by inspecting $LOAD_PATH (an alias for $:).
Since lib is in your load path, you have two options: either name your files with the same names as the constants, so Rails will automatically pick them up when you reference the constant in question, or explicitly require the module.
I also notice that you might be confused about another thing. ApplicationController is not the root object in the system. Observe:
module MyModule
def im_awesome
puts "#{self} is so awesome"
end
end
class ApplicationController < ActionController::Base
include MyModule
end
class AnotherClass
end
AnotherClass.new.im_awesome
# NoMethodError: undefined method `im_awesome' for #<AnotherClass:0x101208ad0>
You will need to include the module into whatever class you want to use it in.
class AnotherClass
include MyModule
end
AnotherClass.new.im_awesome
# AnotherClass is so awesome
Of course, in order to be able to include the module in the first place, you'll need to have it available (using either of the techniques above).
In Rails 3 /lib modules are not loaded automatically.
This is because the line:
# config.autoload_paths += %W(#{config.root}/extras)
inside config/application.rb is commented.
You can try to uncomment this line or, (it worked even better for me), leave this commented (for future reference) and add this two lines:
config.autoload_paths += %W(#{config.root}/lib)
config.autoload_paths += Dir["#{config.root}/lib/**/"]
What worked for me, besides uncommenting config.autoload_paths (I’m on Rails 3.1.3), was to create a initializer like this:
#config/initializers/myapp_init.rb
require 'my_module'
include MyModule
This way I can call mymodule methods from anywhere and as class methods Model.mymodule_method or as instance methods mymodel.mymodule_method
Maybe some expert may explain the implications of this. By now, use it at your own risk.
Edit: Afterwards, I think a better approuch would be:
create a initializer like this:
#config/initializers/myapp_init.rb
require ‘my_module’
Include the module where needed, like this:
1) if you want to use it as "Class Methods" use "extend":
class Myclass < ActiveRecord::Base
extend MyModule
def self.method1
Myclass.my_module_method
end
end
2) if you want to use it as "Instance Methods" include it inside Class definition:
class Myclass < ActiveRecord::Base
include MyModule
def method1
self.my_module_method
end
end
3) remember that include MyModule refers to a file my_module.rb in your load path that must be required first
To use the module lib/my_module.rb in your models and controllers:
In config/application.rb:
config.watchable_dirs['lib'] = [:rb]
In your model (similar idea for your controller):
require_dependency 'my_module'
class MyModel < ActiveRecord::Base
include MyModule
MyModule.some_method
end
This method is described in more detail at http://hakunin.com/rails3-load-paths
It might be the case that you want to explicitly load file(s) under lib directory at time of application initialization. In my config/application.rb, I have an entry as, config.autoload_paths += %W(#{config.root}/lib) Also this might be the case that module name/hierarchy is not same as it is in file or location/name of file is not same as that hierarchy, so auto-load of that file is also not possible. So when I added an entry at bottom of config/application.rb as, require "./lib/file_name_without_extention it worked fine.