1.2 Startup and Application Settings

Load Path:

$ rails console
$ LOAD_PATH

Whenever you start a process to handle requests with Rails (such as with rails server), one of the firstthings that happens is that config/boot.rb is loaded.
There are three files involved in setting up the entire Rails stack:
boot.rb: sets up Bundler and load paths
application.rb: loads rails gems, gems for the specified Rail.env, and configures the application
environment.rb: runs all initializers
All three are run when you need the whole Rails environment loaded. That’s what’s done by runner, console,server, etc.

1.2.1 application.rb

The file config/application.rb is the home to your Rails application settings, and it’s the only file required at the top of config/environment.rb.
You also have the ability to easily cherry-pick only the components needed by your application.

# To pick the frameworks you want, remove 'require "rails/all"'
# and list the framework frailties that you want:

# require "active_model/railtie"
# require "active_record/railtie"
# require "action_controller/railtie"
# require "action_mailer/railtie"
# require "action_view/railtie"
# require "sprockets/railtie"
# require "rails/test_unit/railtie"

1.2.1.1 Load Path Modifications

By default, Rails looks for code in a number of standard directories such as app/models and app/controllers referred to collectively as the load path.

# Custom directories with classes and modules you want to be autoloadable 
# config.autoload_paths+=%W(#{config.root}/extras)
config.autoload_paths+=%W(#{config.root}/app/presenters)

Note that config.root refers to the root directory of your Rails application. the %W functions as a whitespace-delimited array literal and is used quite often in
the Rails codebase for convenience.

1.2.1.2 Time Zones

The default time zone for Rails 4 applications is UTC.

# Set Time.zone  default to the specified zone and make Active Record auto-converttothiszone.
# Run "rake -D time" for a list of tasks for finding time zone names.
config.time_zone='CentralTime(US&Canada)'

1.2.1.3 Localisation

Rails features localization support via locale files. The default locale is :en.

# The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
# config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
# config.i18n.default_locale = :de

1.2.1.4 Generator Default Settings

Rails generator scripts make certain assumptions about your tool chain. Setting the correct values here meanshaving to type less parameters on the command line. For instance, to use Spec without fixtures and Hamlas the template engine, our settings would look like:

# Configure generators values. Many other options are available,
# be sure to check the documentation.
config.generators do |g|
  g.template_engine :haml
  g.test_framework :rspec, fixture: false
end

Note that Rubygems such as rspec-rails, haml-rails, and factory_girl_rails handle this for you automatically.

1.2.2 Initializers

Rails 2 introduced the concept of breaking out configuration settings into their own small ruby files under the config/initializers directory, where they are automatically loaded at startup. You can add configuration settings for your own application by adding ruby files to the initializers directory.

1.2.2.1 Backtrace Silencers

Rails has a mechanism forreducing the size of backtraces by eliminating lines that don’t really add anything to your debugging.

1.2.2.2 Filter Parameter Logging

When a request is made to your application, by default Rails logs details such as the request path, HTTPmethod, IP Address, and parameters. If an attacker somehow gained access to your logs, they may be able toview sensitive information, like passwords and credit card numbers.

1.2.2.3 Inflections

Rails has a class named Inflector whose responsibility is to transform strings (words) from singular to plural,class names to table names, modularized class names to ones without, and class names to foreign keys, etc.

The default inflections for pluralization and singularization of uncountable words are kept in an interestingfile inside the ActiveSupport gem, named inflections.rb.

Most of the time the Inflector class does a decent job of figuring out the pluralized table name for a given class, but occasionally it won’t. This is one of the first stumbling blocks for many new Rails users, but it is not necessary to panic. With a little ad hoc testing beforehand, it’s easy to find out how Inflector will react to certain words. We just need to use the Rails console, which by the way is one of the best things about working in Rails.

$ rails console
>> ActiveSupport::Inflector.pluralize "project" 
=> "projects"
>> ActiveSupport::Inflector.pluralize "virus"
=> "viri"
>> "pensum".pluralize # Inflector features are mixed into String by default
=>"pensums"

1.2.2.4 Custom MEME Types

Rails supports a standard set of MIME types (/, text/html, text/plain, text/javascript, text/css, text/calendar,text/csv, application/xml, application/rss+xml, application/atom+xml, application/x-yaml, multipart/form-data, application/x-www-form-urlencoded, application/json)

Short name	respond_to symbol	Aliases and Explanations
text/html	:html, :xhtml	application/xhtml+xml
text/plain	:text, :txt
text/javascript	:js	application/javascript, application/x-javascript
text/css	:css	Cascading style sheets
text/calendar	:ics	iCalendar format for sharing meeting requests and tasks
text/csv	:csv	Comma-separated values
application/xml	:xml	text/xml, application/x-xml
application/rss+xml	:rss	Really Simple Syndication format for web feeds
application/atom+xml	:atom	Atom Syndication Format for web feeds
application/x-yaml	:yaml	text/yaml - The human-readable data serialization format
application/x-www-form- urlencoded	:url_encoded_form	The default content type of HTML forms
multipart/form-data	:multipart_form	Used for HTML forms that contain files, non-ASCII data, and binary data
application/json	:json	text/x-json, application/jsonrequest - JavaScript Object Notation

If your application needs to respond to other MIME types, you can register them in the mime_types.rb initializer.

1.2.2.5 Secret Token

Certain types of hacking involve modifying the contents of cookies without the server knowing about it.By digitally signing all cookies sent to the browser, Rails can detect whether they were tampered with. The secret_token.rb initializer contains the secret key base, randomly generated along with your app, which isused to sign cookies.

In Rails 4 , the file is secrets.yml in config/

1.2.2.6 Session Store

As of Rails 4, session cookies are encrypted by default using the new encrypted cookie store. The session- store.rb initializer configures the session store of the application, by setting its session store type and key.
The session cookies are signed using thesecret_key_base set in the secret_token.rb initializer. If you are really paranoid, you can change the secret key in secret_token.rb or run rake secret to generate a new one automatically.

1.2.2.7 Wrap Parameters

The wrap_parameters.rb initializer configures your application to work with JavaScript MVC frameworks, such as Backbone.js out of the box.

When submitting JSON parameters to a controller, Rails will wrap the parameters into a nested hash, with
the controller’s name being set as the key. To illustrate, consider the following JSON:

{ "title": "The Rails 4 Way"}

If a client submitted the above JSON to a controller named ArticlesController, Rails would nest the params hash under the key “article”. This ensures the setting of model attributes from request parameters is consistent with the convention used when submitting from Rails form helpers.

{"title": "The Rails 4 Way", "article" => {"title" :"The Rails 4 Way"}}

1.2.3 Additional Configuration

There are additional options, which you can add in additional initializer files.

1.2.3.1 Log-Level Override

# Force all environments to use the same logger level
# (by default production uses :info, the others :debug)
config.log_level=:debug

1.2.3.2 Schema Dumper

Every time you run tests, Rails dumps the schema of your development database and copies it to the test database using an auto generated schema.rb script. It looks very similar to an Active Record migration script; in fact, it uses the same API.
You might find it necessary to revert to the older style of dumping the schema using SQL, if you’re doing things that are incompatible with the schema dumper code (see the comment).

Use SQL instead of Active Record's schema dumper when creating the

test database.This is necessary if your schema can't be completely

dumped by the schema dumper,for example,if you have constraints

or db-specific column types

config.active_record.schema_format=:sql

The value of the RAILS_ENV environment variable dictates which additional environ-ment settings are loaded