I have a rails application that is kind of similar to the active_admin gem. I want to make this existing application into a gem.
I know that you can generate a gem with:
bundler gem gem_name_here
This command creates an empty gem. Which is fine I suppose, I just don't know where to put all my code.
You're ostensibly supposed to put all of your code in the /lib directory. However, my application has an assets pipeline and an app directory with all my models, controllers, and views. I don't know where to place all of these directories in the gem. Any thoughts or ideas?
If you need me to share any code, I'll gladly share it.
You're describing a rails engine. Engine is a miniature rails application that can be used inside other rails app. For more details see official rails guide
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I am trying to use Spree with my RoR application. Ok, I do follow all those guides and FAQs on official website when I want to customize something. That's ok and no problem with it. One question, to which I could not find a clue -- how is that possible, that there is nothing in apps/view, apps/models folders, but it's still working? I mean, yes, I can create something in these folders and redefine the behavior of my views (actually, this is one of the ways of customization), but I really want to understand the internals. I am pretty new to Rails and got used to classic app folder structure.
what you are wondering about is the magic of Rails Engines.
Ruby on Rails allows you to define Engines (your app is one too) and when it looks for views/controllers/etc.. all mounted engines are part of the search path.
So the view is inside the Spree gem, not visible to you - but it still looks in there.
If you put something in your view folder with the same name, it will take precedence over the views in the Rails engine you have in the Gem.
Here is a good guide on how Engines work in Rails:
http://edgeguides.rubyonrails.org/engines.html
One good example of these Engines is the jQuery-rails Gem you probably use inside your Application.
It has no code at all (except for some fallbacks for Rails 3.0 and below that don't have an asset pipeline), but the jQuery.js file in the app/assets/javascripts folder. And since the engine is in the load path you can require the asset that's in there..
The engine itself has the same folder structure as your app (app/views, app/controllers ...)
You can look at the internal structure of Spree here: https://github.com/spree/spree/tree/master/core/app
I've got a simple rails gem (created using bundler) and I'd like to extend it by adding some CSS and javascript functionality. However, I'm unsure how to go about this and where to add the files. In particular, I need need more information on how it all fits together with the asset pipeline once it gets included in another project.
Can anyone give me the lowdown on how this works and either provide some simple examples or link to a tutorial? Literally 1 css and 1 js file is all I'm looking to include. Thanks.
You could write the gem as an engine. This allows you to have an app folder in the gem just as any Rails application would have. You can add models, views, controllers, assets etc.
Once you have it set up it's quite intuitive and it's a familiar way to create a gem if you're used to creating Rails apps.
This should get you started:
http://coding.smashingmagazine.com/2011/06/23/a-guide-to-starting-your-own-rails-engine-gem/
I'm developing a ruby application that uses the models and data from another Ruby on Rails web application as its main data source.
The Rails models were included in this application by including the environment.rb file in the main file like this:
# Require Rails
require_relative "../../RailsApp/config/environment.rb"
This works but there are uninitialized dependencies when loading models that use gems that are defined in the Rails Gemfile. (For example, acts_as_taggable_on, rack-pjax, devise, etc)
This ruby application dependencies are also managed through Bundler, so at the moment the only way to get the application working is to copy and paste the contents from the Rails' Gemfile into the ruby app's Gemfile.
Obviously this approach is not optimal as the gem requirements are duplicated.
Is there a better way to include Rails and the dependencies that its models require in another application? Is there a way to include a Gemfile into another?
Here are some options, in order of simplicity
Just keep everything in one app, a lot of stuff is easier this way
Use plugins to share common code
Use web services to share data
You could extract the models and code out from RailsAppA into a Gem. RailsAppA then includes that Gem and uses it.
The gem can remain in a private repository and does not need published.
Both apps would then do something like:
gem "yourapp-modelage", git: "http://github.com/you/yourapp-modelage.git"
Then, App2 would also use that Gem... How much goes into the Gem will depends on how much you need to re-use.
I have features I would like to be portable between my own Rails applications.
I wonder if I should create a gem or a plugin for each feature I want to be portable (sharable).
They are just for Rails (for now) because they include css, html, js and image files.
But I have been wondering, the things provided with plugins could be provided with gems too but not the opposite? So maybe it's better to learn how to create gems, because then you I don't have to learn how to create both gems and plugins? And gems seem to be more popular these days.
But then, from what I can understand one gem is shared between all rails app in the OS. So that means I can not customize it for each Rails app right? In that case, maybe creating a plugin is better cause it should be allowed to customize (editing css, js etc) each feature and to have it stored inside the Rails app itself and not in the OS level.
Some advices would be appreciated!
UPDATE:
So gem works great with css, html, js and image files? In a plugin I think you can have a MVC, your own models, views and controllers. Quoted from Rails guides "Storing models, views, controllers, helpers and even other plugins in your plugins". Is this possible too in a gem? Eg. I want to add a extension that gives me a nice Shopping cart (with own migrations, mvc, asset files) that will be hooked into the current Rails app. Is this possible as gem or only as plugin?
You're right that gems offer a little more than plugins. Versioning and dependencies on other gems being the main ones for me.
One gem needn't be shared across everything using ruby. You can install multiple versions of a single gem and specify in your environment.rb that a gem requires a specific version. E.g.
config.gem 'my-gem', :version => '1.2.3'
Also you can freeze gems into your rails application so that you know you are working with a specific version.
You might want to look at the jeweler gem which makes creating your own gems easier.
UPDATE
To include CSS, javascript etc I think you'll need to make an Rails engine which can then be bundled as a plugin or a gem. I've not done this but there's some coverage here and here.
The push with Rails 3 seems to be towards gems and away from plugins as a lot of support has been added to make gems work as well or better than plugins ever did. A well constructed gem is a great thing to have and share between different applications, and also reduces the amount of testing you will have to do since you can test the gem thoroughly before integration.
For extensions to Rails that use CSS, HTML and other assets, it might be that you need to build an engine to bundle this all up and allow it to fit neatly into an application.
As of Rails 4, plugins will no longer be supported.
Gems are the way forward.
I want to create a framework for rails application. It will be a rails application but packed into gem (like a Radiant CMS).
It must work like this:
gem install cmsframework
and then:
cmsframework the_app
After that we have a skeleton framework for a rails app, without any controllers, etc. All controllers are loaded from cmsframework gem.
If I want to rewrite some files (for example public/styles.css), I must simply create it in my app (the_app).
If I want new functions in my app I can create a plugin. But the main functionalities must be loaded from cmsframework gem.
What is the best way to implement this?
Maybe start here: http://guides.rails.info/plugins.html. Pay close attention to the parts about adding custom generators and packaging as a gem. This may help as well: http://railscasts.com/episodes/218-making-generators-in-rails-3.
You can use this framework it is very good CamaleonCMS