How to master Ruby on Rails

Question

I've been using online tutorials to learn ROR. I've used www.lynda.com video lessons to get a basic idea what Rails is all about, and for practice I used Rails version 2.0.2, during my training period. But now I'm into a development team in a starter company where there are no senior/experienced programmers to assist me and we're working on gitorious source code modification using Rails 2.3.8. I'm facing a lot of difficulties to understand the source code and some of the major differences I could notice is as follows:

1. Inclusion of XML and HTML to render views in scaffolds, in Rails 2.3.8(I don't understand what this is, as I'd never come across this during my training period using Rails 2.0.2)

2. In gitorious source directory, in addition to Controllers, Models, Views and Helpers there are two more directories namely, Processors and Metals. I don't understand what their significance is.

3. Extensive usage of .yml files. What are those for? In rails 2.0.2, all I came across was the database.yml. Now, in gitorious, I see gitorious.yml. How are all these so customized? I mean, how do rails app(controllers, models, etc..) communicate with gitorious.yml?

With respect to all these questions, how do I move a level or two up, to call myself an "intermediate Rails programmer" from "Rails novice programmer"? and how do I stay updated of new api, deprecations, in all upcoming Rails transitions?

Answer 1

Inclusion of XML and HTML to render views in scaffolds, in Rails 2.3.8

Yes, the way scaffolding works has changed - I can't remember exactly when it changed, but I can certainly believe the change happened between 2.0 and 2.3.

When you generated a scaffold the old way, it would just include 'scaffold' commands in the controller, which would render up a default interface for each of the actions until you replaced them with your own HTML templates.

The new way actually generates the HTML templates as files: so, in the views directory, there will be a directory containing ERb (HTML with embedded Ruby). You can then go and edit those directly.

It also renders XML - this is done by default, but you can choose what other formats are produced. Rails lets you produce multiple output formats for each controller action - so that you can easily produce RESTful web services. So, you obviously produce XML by default, but you may want to produce machine other formats too: XML (including RSS/Atom), JSON (and JSON-P etc.), RDF, YAML. I use this to produce CSV and Excel so users of the site can get data exported to their spreadsheet package.

In gitorious source directory, in addition to Controllers, Models, Views and Helpers there are two more directories namely, Processors and Metals. I don't understand what their significance is.

processors/ is used by ActiveMessaging - it contains ActiveMessaging processors - basically code that gets called as part of communication with a message queue that ActiveMessaging is hooked up to.

metal/ contains code that can best be characterized as 'middleware' - basically, to deploy a Rails application you use a library called Rack which abstracts away the interface between the server and the app itself. It allows you to use the same web server and other infrastructure and switch between different Ruby frameworks - so, if you are using Rails or Sinatra or Merb, Rack lets them all communicate with the same server.

Now, Rack allows you to write 'Metal' code, which is code that gets run directly on the server without the framework getting in the way. The reason you write Metal code is for performance - when Metal code is running, it is running directly rather than with the weight of the Rails framework getting in the way. This way, you can get better performance. I haven't ever had to write any Metal code, so I can't really explain it beyond that.

Extensive usage of .yml files. What are those for? In rails 2.0.2, all I came across was the database.yml. Now, in gitorious, I see gitorious.yml. How are all these so customized? I mean, how do rails app(controllers, models, etc..) communicate with gitorious.yml?

.yml files are files in the YAML format. In Rails, these are mostly used for configuration. Just as XML files are used by Java applications for configuration, .rc files are used in Unix for configuration and .ini files are (were?) used for various apps on Windows for configuration, you can store data in the YAML file which the Rails app uses for configuration. Because of the simplicity of the format, a lot of Ruby and Rails apps use YAML for configuration files.

Ruby has a built-in YAML module that loads these in using methods in the YAML module including YAML.load, YAML.load_file, YAML.load_documents etc. To see how they are being loaded in, I suggest the easiest thing is to find the string "YAML." in the project - or, indeed, the name of the yml files.

With respect to all these questions, how do I move a level or two up, to call myself an "intermediate Rails programmer" from "Rails novice programmer"? and how do I stay updated of new api, deprecations, in all upcoming Rails transitions?

I would suggest that a fair amount of conservatism is appropriate with Rails updates. I'm still using Rails 2.3.3 on a production site, and that's fine. I should probably upgrade to 2.3.8, but I tend to not run with the bleeding edge on production projects.

As for the best way to learn, I'd suggest that you work through Railscasts - these are excellent short screencasts that describe all sorts of useful techniques and help you learn lots about the Rails framework. When you need to do something, obviously there is the API docs - which are okay. The Rails Guides are pretty good and worth reading.

As for books, there's Agile Web Development with Rails - which is a pretty good tutorial. There's also The Rails Way, which is a massive desk reference and in my experience one of the only good ways to learn about some of the minutiae. You might also want to check the StackOverflow question What’s the best resource for learning Rails for a raw beginner? - because although you obviously aren't a raw beginner, the resources recommended are up-to-date and useful for going from novice to intermediate and on upwards. Good luck!