Recent notes - APIdock

July 30, 2008

6 thanks

Different Method for Subdomains

@james

You can also access the subdomain via the subdomains array.

request.subdomains.first

July 30, 2008

8 thanks

Writing and reading a cookie in the same request.

Note that when setting the value of a cookie, the new value won’t be accessible until the next page request. In this way, the cookies hash cannot be used in the same manner as the session hash.

For example:

# given that cookies[:temporary_data] was set to 'foo' in the previous request
cookies[:temporary_data] = 'bar'
p cookies[:temporary_data] # => 'foo'

July 29, 2008 - (v2.1.0)

16 thanks

Scoped using - more simple way

Regarding to the example from james, there is a more simple way to do this:

user.messages.update_all(:read => true)

July 28, 2008 - (<= v2.1.0)

0 thanks

Bug that causes escape buildup

There is a bug in this meethod that causes an escape build up when you have links or image urls for example with ampersands in them. Over time, it goes something like this:

& -> & -> &amp; -> &amp;amp; -> &amp;amp;amp; -> etc

This breaks the url so links and images are not clickable/viewable. To fix, simply unescape before you reescape. Works like a charm. We have the following in an initializer, “html_sanitizer_patch.rb”, that fixes this behaviour.

module HTML
  class WhiteListSanitizer < Sanitizer
    protected
    def process_attributes_for(node, options)
      return unless node.attributes
      node.attributes.keys.each do |attr_name|
      value = node.attributes[attr_name].to_s
      if !options[:attributes].include?(attr_name) || contains_bad_protocols?(attr_name, value)
        node.attributes.delete(attr_name)
        else
          node.attributes[attr_name] = attr_name == 'style' ? sanitize_css(value) : CGI::escapeHTML(CGI::unescapeHTML(value))
        end
      end
    end
  end
end

July 28, 2008 - (<= v2.1.0)

0 thanks

Bug that looks for "500 .html" rather than "500.html"

There is a very small bug in this method of Rails that causes error pages you change in public/ not to be shown, because Rails looks for “404 .html” and “500 .html” (note the space). The fix is simple.

#{status.to_s[0..3]}

needs to become

#{status.to_s[0...3]}

If you’re like me and don’t want to edit Rails itself, at the bottom of environment.rb, stick some code that overwrites this method to fix the bug. We have the following:

module ActionController
  class Dispatcher
    class << self
      private
        def failsafe_response_body(status)
          error_path = "#{error_file_path}/#{status.to_s[0...3]}.html"
          if File.exist?(error_path)
            File.read(error_path)
          else
            "<html><body><h1>#{status}</h1></body></html>"
          end
        end
    end
  end
end

July 28, 2008 - (v2.1.0)

0 thanks

Bug? does not encode options

polymorphic_path(item,options) =polymorphic_path(item)+hash_to_url_query(options)

def hash_to_url_query(hash)
  url = []
  hash.each{|k,v| url << "#{k}=#{v}"}
  "=" + (url * '&')
end

July 28, 2008

15 thanks

Friendlier error message example

The default error messages can be a bit stale and off putting. Try somethings like this:

error_messages_for(
  :user, 
  :header_message => "Oops - We couldn't save your user!", 
  :message => "The following fields were a bit of a problem:", 
  :header_tag => :h1
)

You can also use error_messages_for as follows

<%  form_for User.new do |f| %>
  <%=  f.error_messages :header_message => "..." %>
<%  end  %>

July 28, 2008

2 thanks

":prompt" doesn't work

This does not work:

select :object, :method, options, :prompt => ’-select-’

This does work:

select :object, :method, {:include_blank => ’-select-’}

July 25, 2008 - (v1.0.0 - v2.1.0)

4 thanks

select_options_tag - no more worries...

no more explicit options_for_select calls..

def select_options_tag(name='',select_options={},options={})
  #set selected from value
  selected = ''
  unless options[:value].blank?
    selected = options[:value]
    options.delete(:value)
  end
  select_tag(name,options_for_select(select_options,selected),options)
end

select_options_tag(‘name’,[[‘oh’,‘no’]],:value=>‘no’)

July 25, 2008 - (v1.0.0 - v2.1.0)

4 thanks

haml, an alternative to ERb

Want something nicer looking (and currently, faster!) than using ERb for your views? Have a look at haml (and it’s companion, sass, for stylesheets). It will make you feel all fuzzy on the inside, I promise :P.

ERb example

<div id="profile">
  <div class="left column">
    <div id="date"><%= print_date %></div>
    <div id="address"><%= current_user.address %></div>
  </div>
</div>

haml equivalent

#profile
  .left.column
    #date= print_date
    #address= current_user.address

Shifting to haml from ERb feels strange at first, but after about 20 minutes it starts to feel nice. A little longer and you’ll really start to notice your productivity (and of course, happiness) increase! :). I’ve starting shifting all new projects developed at our work office over to using haml (and sass), it’s been fantastic!

At first I came across a few things that I couldn’t do in haml, though every time a quick read of the overview doc page would show me a simple syntax for overcoming that issue! :) (which out of interest, is located here: http://haml.hamptoncatlin.com/docs/rdoc/classes/Haml.html)

Give the tutorial a shot if you’re interested: http://haml.hamptoncatlin.com/tutorial

July 25, 2008 - (v1.0.0 - v2.1.0)

0 thanks

render template file different from your action (method) name - alternative

Alternative ways to render templates for actions

# Renders the template for foo (foo.html.erb, foo.haml.erb, foo.text.html.haml, whatever :P)
def foo
end

# Renders the template that would be rendered in foo
# (but without the foo controller action being invoked)
def bar
  render :action => 'foo'
end

# Similar to what bar does, but render's a specifically named template
def roar
  render :template => 'foo'
end

# Similar to what roar does, but render's a template
# from outside of the current controller's views directory
def boo
  render :template => 'global/something'
end

July 25, 2008 - (v2.1.0)

6 thanks

link_to with block (Edge Rails)

New ability in Edge Rails to use link_to called with a block, e.g. The following is a view example:

<% link_to some_path do %>
  <strong>Awesome link</strong> -- it's pretty awesome
<% end %>

This change was made in: http://github.com/rails/rails/commit/8190bce8bc7249b7b9f3680195336eb3ca9508ee

Patch in yourself, or likewise you can use the following snippet (which is the new link_to method with modifications [there are also Array extensions on edge to provide .second, .third etc which aren’t present]).

url_helper_extensions.rb

module ActionView
  module Helpers
    module UrlHelper
      def link_to(*args, &block)
        if block_given?
          options = args.first || {}
          html_options = args[1]
          concat(link_to(capture(&block), options, html_options))
        else
          name = args.first
          options = args[1] || {}
          html_options = args[2]

          url = case options
            when String
              options
            when :back
              @controller.request.env["HTTP_REFERER"] || 'javascript:history.back()'
            else
              self.url_for(options)
            end

          if html_options
            html_options = html_options.stringify_keys
            href = html_options['href']
            convert_options_to_javascript!(html_options, url)
            tag_options = tag_options(html_options)
          else
            tag_options = nil
          end

          href_attr = "href=\"#{url}\"" unless href
          "<a #{href_attr}#{tag_options}>#{name || url}</a>"
        end
      end
    end
  end
end

July 25, 2008

2 thanks

If you need something more

Use the brilliant chronic gem: http://chronic.rubyforge.org/

require 'chronic'
Time.now # => Fri Jul 25 00:00:25 0200 2008
Chronic.parse 'tomorrow 8 in the evening'  # => Sat Jul 26 20:00:00 0200 2008
Chronic.parse 'next Monday noon'           # => Mon Jul 28 12:00:00 0200 2008
Chronic.parse 'first Wednesday of Aug'     # => Wed Aug 06 12:00:00 0200 2008
Chronic.parse 'first Wednesday of Aug 7pm' # => Wed Aug 06 19:00:00 0200 2008

July 24, 2008

3 thanks

render_collection

You can wrap render in helpers. For example, render_collection. In app/helpers/application.rb:

module ApplicationHelper
  def render_collection(name, collection)
    render :partial => "shared/#{name}", :collection => collection
  end
end

In views:

<h2>Comments</h2>
<%= render_collection :comments, @photo.comments %>

July 24, 2008

8 thanks

render template file different from your action (method) name

In some cases you have to avoid rails magic that uses template names named as your ActionMailer method.

rails magic

def daily_notification
  # ...
end
# will look for daily_notification.erb

def weekly_notification
  # ...
end
# will look for weekly_notification.erb

your case

Just give necessary value to @template instance variable.

def setup
  # ...
  @template = 'notification'
end

def daily_notification
  # ...
end
# will look for notification.erb

def weekly_notification
  # ...
end
# will look for notification.erb

July 24, 2008 - (v1.0.0 - v2.1.0)

0 thanks

Extract plain text body from TMail parsed email

Here’s a monkey patch for TMail::Mail I wrote to recurse through a message and extract all plain text body components of that message, returning an Array. For most use cases, the resulting Array will contain one String element.

Currently I put this code in a file called lib/tmail_extensions.rb and require ‘tmail_extensions’ in environment.rb

module TMail
  class Mail
    def plain_text_body
      gather_plain_text_parts(self).flatten
    end

  private
    def gather_plain_text_parts(part)    
      returning [] do |message|
        message << part.body.strip if part.content_type == 'text/plain'        
        part.parts.each { |p| message << gather_plain_text_parts(p) }
      end
    end
  end
end

July 24, 2008 - (v2.1.0)

20 thanks

automatically generate scopes for model states

or better known as “throw on some more tasty meta-programming” :). Given an example of a model which has a state (String) which must from a set of defined values, e.g. pending, approved, denied.

class User < ActiveRecord::Base
  STATES = [ 'pending', 'approved', 'denied' ]

  validates_inclusion_of :state, :in => STATES

  # Define a named scope for each state in STATES
  STATES.each { |s| named_scope s, :conditions => { :state => s } }
end

This automatically defines a named_scope for each of the model states without having to define a named_scope manually for each state (nice and DRY).

July 24, 2008 - (v1.0.0 - v2.1.0)

1 thank

Custom environment constants

Custom environment level constants can be passed in to your rails application (server, console, whatever) like this):

# bash, tcsh, whatever shell
GAMEMODE=pregame script/server

Within rails this constant can be accessed by

ENV['GAMEMODE']
=> "pregame"

ENV['DOES-NOT-EXIST']
=> nil

July 23, 2008

3 thanks

options_for_select further example (using a collection and with a default value)

In this example, we are editing a collection of region records, each with its own select list of countries. (Region belongs_to :country.) If the region doesn’t have a country associated, then we want a default message of “unassigned”. Of course, if the region does have a country associated then we want that country displayed:

<% name = "region[" + region.id.to_s + "][country_id]" %>
<% id = "region_" + region.id.to_s %>

<%= select_tag(id, options_for_select([["unassigned" , "0" ]] +
                     Country.to_dropdown, region.country_id),

{:name => name} ) %> This give us:

<select id="region_3" name="region[3][country_id]">
  <option value="0">unassigned</option>
  <option selected="selected" value="12">England</option>
</select>

NB: we’re using the handy acts_as_dropdown plugin (http://delynnberry.com/projects/acts-as-dropdown/) but we could just as easily prepare the select list with map / collect as above.

July 23, 2008 - (<= v2.1.0)

10 thanks

:only, :except and passing in multiple parameters

To specify that the filter should be applied to or excluded from given controller actions, use the :only and :except parameters. To pass in multiple controller actions use an array:

before_filter :authorize, :except => [:index, :show]
before_filter :authorize, :only => :delete

July 23, 2008

1 thank

Using .map(&:item)

You can only use .map(&:item) with find(:all, not find(:first. For example; the first works, but the second does not.

@person = Person.find(:all, :conditions => {
  :id => @person.id}, :select => "name").map(&:name)

@person = Person.find(:first, :conditions => {
  :id => @person.id}, :select => "name").map(&:name)

July 23, 2008

4 thanks

Keep your controllers clear

When you use redirect_to or render with flash[:notice] or flash[:error], you can define some helper methods in your ApplicationController (or somewhere you want):

class ApplicationController < ActionController::Base

  protected

    %w(notice error).each do |message|
      class_eval <<-END_EVAL
        def redirect_#{message}(url, message)
          flash[:#{message}] = message
          redirect_to url
        end

        def render_#{message}(action, message)
          flash[:#{message}] = message
          render :action => action
        end
      END_EVAL
    end
end

Now you have four methods - redirect_notice, redirect_error, render_notice and render_error.

July 23, 2008 - (>= v2.1.0)

0 thanks

Another solution for visual_effect in code block example in link_to_remote

Update: Code block example in link_to_function not link_to_remote (can’t edit subject annymore :( )

This doesn’t work:

page[:details].visual_effect :toggle_blind

My solution:

page.visual_effect :toggle_blind, ‘details’

July 23, 2008

5 thanks

Custom annotation types

For group work you may need something more than FIXME, OPTIMIZE and TODO. Just create new rake file and place it to lib/tasks:

require 'source_annotation_extractor'

task :notes do
  SourceAnnotationExtractor.enumerate "WTF|OMG", :tag => true
end

namespace :notes do
  desc "Enumerate all WTF annotations"
  task :wtf do
    SourceAnnotationExtractor.enumerate "WTF"
  end

  desc "Enumerate all OMG annotations"
  task :omg do
    SourceAnnotationExtractor.enumerate "OMG"
  end
end

or create an array of new types and generate tasks dynamicaly.

July 23, 2008

14 thanks

Pass id collections with check box tags

It can be useful to pass a collection of ids to a controller, especially in the case of a has_many relationship, for example:

User has_many Roles

In your view you could have something like:

<ul>
  <% @roles.each do |role| %>
      <li>
        <%= check_box_tag 'role_ids[]', role.id -%>
        <%= h role.name -%>
      </li>
  <% end %>
</ul>

Note the square brackets after role_ids - this is important for passing a collection through to the controller.

If you place this in a form and submit it, you can expect to see a param passed into the controller that looks like:

"role_ids"=>["1", "2", "3"]

July 23, 2008 - (v1.0.0 - v2.1.0)

2 thanks

subdomains from request

Useful for discovering what domain/subdomain(s) the current request came from (Rails application may operate differently depending on which subdomain is passed in, this is a great way to segment functionality using the route).

request.host.split('.')

Doesn’t get much simpler than that :).

Likewise if you want to see only the subdomain component(s). Given a domain, example.com

request.host.gsub('example.com', '').split('.')

July 23, 2008 - (<= v2.1.0)

9 thanks

Easy and effective admin authentication

Great for use within an AdminController (in which all other administrative controllers inherit from AdminController).

class AdminController < ApplicationController
  before_filter :authenticate

  def authenticate
    authenticate_or_request_with_http_basic('Administration') do |username, password|
      username == 'admin' && password == 'password'
    end
  end
end

July 23, 2008 - (<= v2.1.0)

9 thanks

perform update_all scoped within a has_many collection

For example: having two models, User and Message (user has_many messages, each message has a boolean flag called ‘read’). You want to mark all messages as read for a particular user.

Mark all messages as read for a particular user

Message.update_all({:read => true}, {:id => user.messages})

July 23, 2008

6 thanks

Loading fixtures in migrations

This helper is wrapper around Fixtures#create_fixtures and just load fixtures from specified directory (db/migrate/data by default):

class ActiveRecord::Migration
  def self.load_data(filename, dir = 'db/migrate/data')
    Fixtures.create_fixtures(File.join(RAILS_ROOT, dir), filename)
  end
end

It is usefull for tables with data like country list:

class CreateCountries < ActiveRecord::Migration
  def self.up
    create_table :countries do |t|
      t.string :name, :code, :null => false
      t.timestamps
    end
    load_data :countries
  end

  def self.down
    drop_table :countries
  end
end

July 22, 2008

1 thank

Full Select

The full select using this would be something like:

Code Example

<%= select_tag(“job[state_id]”, options_from_collection_for_select(State.find(:all), “id”, “name”)) %>