Hidden Features of Ruby on Rails [closed]

Answer 1

To see a list of gems that are installed, you can run:

gem server

Then point your browser at:

http://localhost:8808

You get a nicely formatted list of your gems with links to rdoc, the web and any dependencies. Much nicer than:

gem list

Answer 2

If you add routing for a resource:

ActionController::Routing::Routes.draw do |map|
  map.resources :maps
end

And register additional mime-types:

Mime::Type.register 'application/vnd.google-earth.kml+xml', :kml

You don't need a respond_to block in your controller to serve these additional types. Instead, just create views for the specific types, for example 'show.kml.builder' or 'index.kml.erb'. Rails will render these type-specific templates when requests for '/maps.kml' or '/maps/1.kml' are received, setting the response type appropriately.

Answer 3

You can take advantage of the fact that Ruby class definitions are active and that Rails caches classes in the production environment, to ensure that constant data is only fetched from the database when your application starts up.

For example, for a model that represents countries you'd define a constant that performs a Country.all query when the class is loaded:

class Country < ActiveRecord::Base
  COUNTRIES = self.all
  .
  .
  .
end

You can use this constant within a view template (perhaps within a select helper) by referring to Country::COUNTRIES. For example:

<%= select_tag(:country, options_for_select(Country::COUNTRIES)) %>

Answer 4

ActionView::Base.default_form_builder = MyFormBuilderClass

Very useful when you're creating your own form builders. A much better alternative to manually passing :builder, either in your views or in your own custom_form_for helper.

Answer 5

Rails 2.3.x now allows you to do:

render @items

much simpler..

Answer 6

in your environment.rb, you can define new date/time formats e.g.

[Time::DATE_FORMATS, Date::DATE_FORMATS].each do |obj|
  obj[:dots] = "%m.%d.%y"
end

so then in your views you can use:

Created: <%= @my_object.created_at.to_s(:dots) %>

which will print like:

Created: 06.21.09