I created an engine which provides an ui component as a cell. The corresponding gem (criteria_operator-ui_component) contains nearly no code inside the lib folder, because for cells to function properly I had to work inside the assets path. The base file of the gem looks like this:
require 'criteria_operator/ui_component/engine'
require 'cells/rails'
module CriteriaOperator
module UiComponent
# Your code goes here...
end
end
The engine doesn't contain much, either:
module CriteriaOperator
module UiComponent
class Engine < ::Rails::Engine
require 'jquery-rails'
require 'criteria_operator'
isolate_namespace CriteriaOperator::UiComponent
end
end
end
To me, it looks like the gem couldn't even know about the cell, but as far as I know I'm not allowed to include anything from outside the lib folder. Also, testing the cell in the dummy application within the project is working fine.
Now I'm using this engine inside a real Rails application. In the gemfile, I included the following:
gem 'criteria_operator'
gem 'cells' # i added these three, because `bundler list` didn't show me
gem 'cells-rails' # `cells-rails` and `cells-erb` even though they are listed
gem 'cells-erb' # as dependencies for the engine
gem 'criteria_operator-ui_component'
I mounted the routes
mount CriteriaOperator::UiComponent::Engine => '/criteria_operator-ui_component'
and tried using the cell CriteriaOperator::UiComponent::CriteriaEditor like I did in the dummy application. Inside erb:
cell('criteria_operator/ui_component/criteria_editor', #op)
or from code:
include Cell::RailsExtensions::ActionController
def whatever
cell(CriteriaOperator::UiComponent::CriteriaEditor, #op).call()
end
The error is ActionView::Template::Error (uninitialized constant CriteriaOperator::UiComponent::CriteriaEditor).
What am I doing wrong? Am I just missing something when using the engine, or is the engine itself implemented the wrong way? And if that's the case, why does the dummy application work? I'm totally stuck, this is my first time creating a Rails Engine as well as my fist time working with cells...
The full code of the engine (including the dummy application) can be found on GitHub (this isn't supposed to be any advertisement, it's just in case anyone needs additional information).
You're calling CriteriaOperator::UiComponent::CriteriaEditor but that class/module does not seem to exist.
CriteriaOperator::UiComponent::Engine works OK because it's defined in the engine itself.
I'm guessing that your sample application works because it's using the view-based invocation like cell('criteria_operator/ui_component/criteria_editor') which presumably works with the javascript? You can't use the "code" version without defining the cell as a class like this:
https://github.com/trailblazer/cells#cell-class
Related
How do I extend a class that is defined by a gem when I'm using rails 6 / zeitwerk?
I've tried doing it in an initializer using require to load up the class first.
I've tried doing it in an initializer and just referencing the class to let autoloading load it up first.
But both of those approaches break auto-reloading in development mode.
I've tried putting it in lib/ or app/, but that doesn't work because then the class never gets loaded from the gem, since my new file is higher up in the load order.
There is a similar question here, but that one specifically asks how to do this in an initializer. I don't care if it's done in an initializer or not, I just want to figure out how to do it some way.
What is the standard way of doing something like this?
I do have one nasty hack that seems to be working, but I don't like it (update: this doesn't work either. reloading is still broken):
the_gem_root = $LOAD_PATH.grep(/the_gem/).grep(/models/).first
require("#{the_gem_root}/the_gem/some_model")
class SomeModel
def my_extension
...
end
end
I know is late, but this was a real pain and someone could find it helpful, in this example I'll be using a modules folder located on app that will contain custom modules and monkey patches for various gems.
# config/application.rb
...
module MyApp
class Application < Rails::Application
config.load_defaults(6.0)
overrides = "#{Rails.root}/app/overrides"
Rails.autoloaders.main.ignore(overrides)
config.to_prepare do
Dir.glob("#{overrides}/**/*_override.rb").each do |override|
load override
end
end
end
end
Apparently this pattern is called the Override pattern, it will prevent the autoload of your overrides by zeitwerk and each file would be loaded manually at the end of the load.
This pattern is also documented in the Ruby on Rails guide: https://edgeguides.rubyonrails.org/engines.html#overriding-models-and-controllers
I've created a gem (TranslationsGem) which I use in multiple projects (an engine and a Rails app). This gem sets up several hashes which are loaded into the I18n backend.
A method #store_dynamic_translations sets up several hashes which are loaded into the I18n backend. It basically works like this:
I18n.backend.store_translations(:en, { test: { property: 'value' } })
My tests confirm the method and translation loading works correctly. I can't however get it to work in the host engine and Rails app.
In my test environment I have to execute the method in my test_helper to ensure the translations are loaded correctly. Outside the test environment I cannot seem to get it working correctly. I can verify that the method is executed, but the translations aren't loaded.
I have tried numerous things for hours, like executing the method in the Engine initializer and using ActiveSupport hooks. In the host Rails app I tried executing the #store_dynamic_translations in an initializer but to no avail.
Oddly enough, if I execute the #store_dynamic_translations in my Rails app controller or view, it works. Is there any way to set this up at app boot time?
EDIT: I've setup an example repository which contains the current setup.
A Gem which dynamically stores translations into the I18n backend.
A Rails Engine which loads the gem and should have its translations available
In the test in question uncommenting the MyI18n::Translations.store_dynamic_translations directive makes the test pass. But it should be possible to do from within an engine initializer I think?
As per Emill Kampp's suggestion, the correct hook was after_initialize. I specified this in engine.rb:
module Blorgh
class Engine < ::Rails::Engine
isolate_namespace Blorgh
config.after_initialize do
MyI18n::Translations.store_dynamic_translations
end
end
end
I have written a generator which creates the following ruby file and folder:
app/tests/test.rb
in the test.rb file I have a Test class which looks like this:
class Test < MyCustomModule::MyCustomClass::Base
...
end
Now, I want to use its functionality in one of the show.html.erb files creating new instance like this:
Test.new(...).render(...).html_safe
but I am getting the following error:
uninitialized constant MyCustomModule::MyCustomClass::Base
I have use the following answer to link my gem and my rails application. It seems to work as I am able to use the generator, but the gem module and class are not seen in the rails application.
Could anyone tell how to fix this issue?
I have try to follow the tips posted here but still nothing changed:
Adding config.autoload_paths += Dir["#{config.root}/lib/**/"] in application.rb file
I have created my gem structure looking at CarrierWave gem, so the naming should be correct
I try to disable config.threadsafe! but it is already disabled since config.cache_classes and config.eager_load are set to false in development
DEPRECATION WARNING: config.threadsafe! is deprecated. Rails
applications behave by default as thread safe in production as long as
config.cache_classes and config.eager_load are set to true.
Also, looking at adding-asset-to-your-gems rails documentation, it is said that:
A good example of this is the jquery-rails gem which comes with Rails
as the standard JavaScript library gem. This gem contains an engine
class which inherits from Rails::Engine. By doing this, Rails is
informed that the directory for this gem may contain assets and the
app/assets, lib/assets and vendor/assets directories of this engine
are added to the search path of Sprockets.
So, I have done this, and put my model class file in assets folder, but the result is the same.
The following screenshots demonstrate my real case:
The screenshot below displays my gem file structure
Here you can see how I am loading the gem in my Rails application Gemfile:
gem 'thumbnail_hover_effect', '0.0.3', github: 'thumbnail_hover_effec/thumbnail_hover_effec', branch: 'master'
Then I am using the gem generator a ruby file with a cutstom name in app/thumbnails/test.rb folder with the following code:
class Test < ThumbnailHoverEffect::Image::Base
...
end
and trying to use the Test class gives me uninitialized constant ThumbnailHoverEffect::Image::Base error.
Back in the gem files, these are how the thumbnail_hover_effect file looks like
require 'thumbnail_hover_effect/version'
require 'thumbnail_hover_effect/engine'
require 'thumbnail_hover_effect/image'
module ThumbnailHoverEffect
# Your code goes here...
end
and hoe the image file looks like:
module ThumbnailHoverEffect
#
class Image
...
end
end
From what you've posted here there is no ThumbnailHoverEffect::Image::Base defined. Rails autoloading conventions (which you should not be depending on a gem btw, more on that later) would be looking for this file in thumbnail_hover_effect/image/base.rb, but the directory structure you printed does not have that. Of course you could define the class in thumbnail_hover_effect/image.rb and it would work, but the abridged snippet you posted does not show that. So where is ThumbnailHoverEffect::Image::Base defined?
If it's in thumbnail_hover_effect/image/base.rb then that would indicate the file is not being loaded. You can sanity check this by putting a puts 'loading this stupid file' at the top of thumbnail_hover_effect/image/base.rb. That will allow you to bisect the problem by seeing whether there is a problem with your definition of the class, or whether the problem is with loading the proper files. Debugging is all about bisecting the problem.
I have a Rails app that uses a gem called ActsAsTaggableOnSteroids, which is a Rails Engine. Specifically, I'm using PavelNartov's fork of the gem. But nevermind that.
I need to add specific functionality to the Tag model, which is supplied by the engine.
But, according to my understanding of Rails engines and the magical loading functionality in Rails, if I put a file called "tag.rb" in my models directory, then it will completely replace the one from the Engine.
Ideally, I would be able to do something like:
class Tag < ActsAsTaggable::Tag
# my stuff
end
...but alas, that doesn't work because the model supplied by the engine is not namespaced.
So, I came up with this nightmare, which I put in app/models/tag.rb:
path = ActsAsTaggable::Engine.config.eager_load_paths.grep(/models/).first
require File.join(path, 'tag')
Tag.class_eval { include TagConcern }
But there has to be a better way! I feel like I'm missing something. I'd prefer not to add this strangeness to my app if possible.
Just require the file by looking up the path of the gem's model:
require File.join(Gem::Specification.find_by_name("bborn-acts_as_taggable_on_steroids").gem_dir, 'app/models/tag')
Tag.class_eval do
# ...
end
So there's this great plugin I've gotten used to using in my Rails 2 projects called Bootstrapper. It essentially duplicates the functionality of the seeds.rb file, but I like it because it lets you break up your bootstrap process into concise chunks.
Anyway, I've gone so far as to fork the project and attempt to turn it into a Rails 3 gem. I've been able to get the gem to initialize and register the rake tasks and generators OK. However, I'm running into a problem with the Bootstrapper class itself. It won't load in the Rails project unless it's in a module.
That is, if I place the Bootstrapper class in a file by itself and require that file in my Railtie, then in my Rails app, it can't find the Bootstrapper class. If I put the class in a module and call Bootstrapper::Bootstrapper everything is peachy.
The code that actually requires the Bootstrapper class is this:
ActiveSupport.on_load :active_record do
require 'bootstrapper/bootstrapper'
end
The source is available here:
http://github.com/jrmehle/bootstrapper/tree/make_gem
Autoload paths actually has an annoying feature of following filesystem paths. For example in your lib or extras (depending on what you autoload) you might have the following file structure:
lib/bootstrapper/bootstrapper.rb
# in this case, Bootstrapper::Bootstrapper.class = Class in rails c
# ie: you don't get a NameError exception
More specifically,
lib/bootstrappers/bootstrapper.rb
# Bootstrapper::Bootstrapper => NameError
# Bootstrappers::Bootstrapper => works
If you really want the other way, you can move everything into your lib/bootstrapper.rb source file but meh, I don't like doing that, that's not how gems are organized. In rails3, you'll find the autoloading pretty nice once you use modules everywhere (which can be painful).
Rails3 uses /extras instead of /lib but it's not required, it's just the default (commented out) from rails new. To switch, you just autoload extras instead of lib.