Styleguide for Rails Projects

Principles

DRY – Don’t Repeat yourself.
http://www.jensjaeger.com/2008/04/das-dry-prinzip/ (german)
http://en.wikipedia.org/wiki/DRY

KISS – Keep it Simple Stupid
http://www.jensjaeger.com/2008/04/das-kiss-prinzip/ (german)
http://en.wikipedia.org/wiki/KISS_principle

General

General Ruby Styleguide
http://rubygarden.org/ruby/page/show/RubyStyleGuide

General Rails Styleguide:
http://wiki.rubyonrails.org/rails/pages/CodingStandards

Language

Everything in the source code must be written in english. Including comments, variable names and function names.

Encoding

All files must be encoded with UTF-8.

Methods

Every method should have a meaningful name.
For a procedure name use a strong verb.
Example:

Report.print

For a function name use a description of the return value
Example:

Report.publishing_date

Avoid meaningless or wishy-washy verbs.
Descripe everything the method does.
Make names of routines as long as necessary.
The average length of methods should be from 15 to 20 characters.

Variables

Every variable should have a meaningful name.
The most consideration in naming is that the name fully and accurately descripe the entity the variable represents.
The average length of a variable should be from 8 to 15 characters.
Use shorter name only for iterators in really short scopes.
Example:

reports.each do |r|
  r.print
end

The scope of a variable should be as short as possible.
Arrays should have a plural name.
Example:

reports = Report.find(:all)

Everything else should have a singular name.
Example:

report = Report.find_by_id(1)

Constants

Naming like variables.
There should be no numbers in the sourcecode. Every number should be a constant defined in environment.rb.
Example:

PAG_PAGES = 10 #items per page for pagination

Comments

Comment as much as possible.
You shouldn’t comment WHAT your code does (this would be hurt the DRY-Principle), you should comment WHY your code does something.

Stay DRY

If you are doing something more than once, extract it into a method. This is especially the case when it comes to conditional queries. So instead of writing:

@reports = Report.find(:all, :conditions => ["deleted = ", 1])

you should write a method:

class Report < ActiveRecord::Base
  def find_deleted
    find(:all, :conditions => ["deleted = ", 1])
  end
end

Paranthesis

Use paranthesis with “standard” method calls and no paranthesis for helper-style hash arguments. Example:

Report.find_by_id(1)
#instead of
Report.find_by_id 1

but

ink_to "view", { :action =>; "view" }
#instead of
link_to("view", { :action => "view" })

Acknowledgments

Thanks to Florian Gilcher for the helpful comments.