Local gem class is not found in Rails application - ruby-on-rails

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.

Related

Auto include in Rails Console

I find myself having to type (for example)
include PathHelper
every time I load the Rails Console.
Is there a way to configure the Rails console to automatically include certain modules?
The syntax for configuring rails console has changed. I found this on RailsGuides:
http://guides.rubyonrails.org/configuring.html#rails-general-configuration
console do
# this block is called only when running console,
# so we can safely require pry here
require "pry"
config.console = Pry
end
Just in case anyone still feel confused, the simplest way to do this is:
go to the root directory of your project
create an .irbrc file(if you use rails console) or .pryrc file(if you use pry)
put whatever you need to include in it
For example, if you use the default rails console and need to include PathHelper, just put it in the file:
# RootDirectoryOfYourProject/.irbrc
include PathHelper
The PathHelper will be included automatically when you do rails console
If you are still looking for an answer, this is what I do,
I created a file ~/.irbrc in which you put all the code you want to be auto loaded in your rails console.
This is the content of my file:
require "awesome_print"
include Rails.application.routes.url_helpers
AwesomePrint.irb!
def y(obj)
puts obj.to_yaml
end
I would check out this question.
Basically, modify your config/application.rb file to include the paths to any modules you want to auto-load.

Rails bootstrap gem monkeypatching method not working

I'm using the excellent twitter-bootstrap-rails gem. There is a helper within that gem (NavbarHelper) which is used to generate Bootstrap navbars with a Ruby helper. I want to monkey patch the gem such that the dropdown lists won't have carets.
So, I looked into the source and found the relevant method here. All I have to do is override it. I created a new file in config/initializers called navbar.rb with the following content:
NavbarHelper.module_eval do
def name_and_caret(name)
"HELLO WORLD"
end
end
Presumably, all of the dropdown titles then should be rendered as "HELLO WORLD" in my app (as referenced by the gem source). However, this is not occurring, and the gem does not appear to be monkeypatched at all.
I tried placing puts NavbarHelper.methods - Object.methods in the initializers file, and there were no results, which makes me think that Rails is not loading the gem correctly before the initializers. I have also checked and verified that the gem is not using autoload for its helpers.
Edit
What may be complicating this is the fact that my Gemfile includes the gem in the following manner:
gem 'twitter-bootstrap-rails', git: 'git://github.com/seyhunak/twitter-bootstrap-rails.git', branch: 'bootstrap3'
I'm not sure if this specific versioning means the monkeypatching doesn't work.
Edit #2
It seems there is only one version of the gem on my system, so I don't think that's the issue. Also, I have tried placing require 'twitter-bootstrap-rails at the top of the initializers file, with no results.
The problem is that you patch the method on this module but the module already got included at this point. Try to define this in your application_helper.rb
def name_and_caret(name)
super("blub #{name}")
end

Creating an install generator for a Ruby gem

I'm pretty new to building Ruby gems and am taking a stab at my first one. I'm in the middle of writing a generator for my gem that will generate a migration in my Rails app. I'm looking to simply include the gem in the Rails application, run "rails g mygem:install" to have it create the migrations, then run "rake db:migrate" to finalize everything.
I've found several different ways to accomplish similar tasks, but so far nothing has worked. I cannot seem to get the Rails application to find the generator. The latest guide I've tried is located here: http://www.railsdispatch.com/posts/how-rails-3-enables-more-choices-part-1.
Here is what my current gem structure looks like:
-lib/
-generators/
-templates/
-some_migration.rb
-install_generator.rb
-gemname/
-rails/
-railtie.rb
-engine.rb
-tasks/
-gemname.rake
-gemname.rb
-spec/
-gemname.gemspec
Here is what my install_generator.rb file looks like:
require 'rails'
module Gemname
class InstallGenerator < ::Rails::Generators::Base
include Rails::Generators::Migration
source_root File.expand_path('../templates', __FILE__)
desc "add the migrations"
def self.next_migration_number(path)
unless #prev_migration_nr
#prev_migration_nr = Time.now.utc.strftime("%Y%m%d%H%M%S").to_i
else
#prev_migration_nr += 1
end
#prev_migration_nr.to_s
end
def copy_migrations
migration_template "some_migration.rb", "db/migrate/some_migration.rb"
end
end
end
I'm not sure if there's something I'm missing. I'm testing with a Rails 3.2 application that has my gem listed in its Gemfile and the gem is installed. Is there anything wrong with gem folder structure that might be preventing my generator from showing up? Do I need to require something somewhere?
Any help is appreciated.
Rails no longer automatically loads everything in lib by default, like it used to. For a few methods of requiring your files, check out the answers to this question - Best way to load module/class from lib folder in Rails 3?.
Well, I'm not sure which of the changes I made fixed my problem, but here is what I did:
Changed the name of my generator to gemname_generator.rb and the directory structure of my generator to this:
- lib/
-generators/
-templates/
-gemname_generator.rb
Added this line to my generator:
namespace 'gemname'
I'm now able to run "rails g gemname" in my Rails application and have it call my generator.

Converting Rails 2 plugin to Rails 3 gem

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.

How to gemify a Rails (engine) plugin?

I have a engine style Rails plugin from which I can create a gem using Jeweler. But when I require it in my Rails environment (or erb) the models within the plugin are not loaded. I have followed a number of tutorials and read just about everything on the subject.
# environment.rb
config.gem 'myengine'
# in irb
require 'myengine'
I have unpacked the gem and verified that all files are present. My init.rb has been moved to a new folder called 'rails' as per. All files in 'lib' are automatically added to the $LOAD_PATH, so require 'myengine' runs lib/myengine.rb. I verified this by putting a puts 'hello' within.
Is it because of the physical presence of plugins in a known place that Rails can add all the models, controller etc. to the relevant load_paths? Do I need to replicate this manually when using a gem?
Would gemspec require_paths be a way of adding additional paths other than lib? I assume however that Rails does not just require every single file, but loads them on demand hence the need for the filename and class name to match?
%w{ models controllers helpers }.each do |dir|
path = File.join(File.dirname(__FILE__), 'app', dir) + '/'
$LOAD_PATH << path
puts 'requiring'
Dir.new(path).entries.each do |file|
if file =~ /\.rb/
puts file
require file
end
end
end
By adding the above to lib/myengine.rb all the models/controllers are required. But like I said in my question this is unlikely to be a good way forward.
Offhand I'd say the part about adding those directories to the search path is right on. What you shouldn't need to do is require each file manually (as you allude to in your last sentence). What Rails does when you reference a non-existent constant is to search for a file with the same name (underscored of course) in the load path.
If for some reason you can not abide by the constraint (think about it long and hard) then you are going to need to dig deeper into Rails and see how the reloading mechanism works so you can tie into it properly in development mode.
The problem was the files (in app) where not being added to the gem because when using Jeweler it only automatically adds files to required_paths which are committed to git.

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