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March 10, 2012
3 thanks

flash messages

In rails 3.1 the following does not work for me

redirect_to { :action=>'atom' }, :alert => "Something serious happened" 

Instead, you need to use the following syntax (wrap with parens)

redirect_to({ :action=>'atom' }, :alert => "Something serious happened")
March 5, 2012
0 thanks

Example of conditions using


validates :number, :presence => { :if => :quota_file? }

def self.quota_file?
March 5, 2012
0 thanks

won't refresh updated_at

This will not cause :updated_at column to refresh, while ActiveRecord::Base#increment! would.

February 23, 2012
0 thanks

Be careful with path vs. endpoint

URI.join uses a delimiter – forward slash (/) – to decide if joined strings are a path or endpoint. In order to include strings as part of the path, they must end with a forward slash (/). Otherwise, they are assumed to be an endpoint and are overritten by your new “endpoint”.

Used this way, it (kind of) makes sense:

1.9.2p290 :021 > URI.join("http://localhost/test","main.json")
 => #<URI::HTTP:0x007fa68e81c270 URL:http://localhost/main.json> 

1.9.2p290 :022 > URI.join("http://localhost/test/","main.json")
 => #<URI::HTTP:0x007fa68e80e0d0 URL:http://localhost/test/main.json> 

It is especially confusing when you pass 3 strings and the 3rd (your endpoint) overwrites the 2nd (which you expected to be part of the path).

1.9.2p290 :023 > URI.join("http://localhost/", "test", "main.json")
 => #<URI::HTTP:0x007fa68cec0ba0 URL:http://localhost/main.json> 

1.9.2p290 :024 > URI.join("http://localhost/", "test/", "main.json")
 => #<URI::HTTP:0x007fa68ce14c60 URL:http://localhost/test/main.json> 

Now, consider that you are probably using a variable for the string value of ‘test’.

1.9.2p290 :025 > controller = 'test'
1.9.2p290 :026 > URI.join("http://localhost/", controller, "main.json")
 => #<URI::HTTP:0x007fa68cec0ba0 URL:http://localhost/main.json> 

Your `controller` is simply ignored. Or rather, your endpoint(?) was overwritten.

I’m not sure what versions of ruby this affects. As you can see I am using 1.9.2p290.

February 20, 2012
0 thanks

How to user method 'from'


# => "SELECT `users`.* FROM posts"
February 20, 2012
0 thanks

How to user method from'


# => "SELECT `users`.* FROM posts"
February 15, 2012 - (<= v2.3.8)
0 thanks

@ssoroka and @drova and future readers

I guess these two have already found a solution, but future readers might have not. index and references do not map perfectly

change_table :foo do |t|
  t.references :bar
  t.index      :bar_id

references gets the model name while index gets the column name.

February 15, 2012 - (<= v2.3.8)
0 thanks

Not working in create_table

When using the index method within a create_table statement, it does not have any side effect - at least not in MySQL.

create_table :comment do |t|
  t.belongs_to :post


  # not working inside create_table !
  t.index :post_id

It is working properly in change_table though

change_table :comment do |t|
  t.belongs_to :user

  # this works inside change_table
  t.index :user_id

Unfortunately this flaw is not reported in any way. The index is just not created.

I have only tested this with the mysql2 driver in Rails 2.3.x. I’m not sure, if this happens in other versions/adapters as well.

February 12, 2012 - (v1_8_6_287 - v1_9_2_180)
2 thanks

More Examples


class User < Struct.new(:name, :age, :gender) 

user = User.new("Matz", 43, "male")
February 10, 2012 - (>= v3.1.0)
0 thanks

:defaults no longer work

I’m afraid that :defaults option doesn’t work anymore.

<%= javascript_include_tag :defaults %>

it loads “defaults.js”

Instead, to load all .js files now use

<%= javascript_include_tag "application" %>
February 9, 2012 - (v1.2.0 - v3.1.0)
1 thank

: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:

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

Stolen from: http://apidock.com/rails/ActionController/Filters/ClassMethods/before_filter

February 9, 2012 - (v2.3.2 - v3.1.0)
0 thanks


This is inverse operation of select. If block return false add item to array.

[1,2,3,4].reject {|n| n%2==0}

> [1, 3]

Like select method with inverse.

January 31, 2012 - (v3.0.0 - v3.1.0)
0 thanks

undocumented events/symbol/types

@nessur is right: drop the “before_” and “after_” prefixes and you have the possible values for the uninformatively named `symbol` param: create, save, update and validate.

So to remove all validations for a model do: `reset_callbacks :validate`

January 31, 2012
2 thanks

To use with factory_girl and prevent leaking file handles

As insane-dreamer noted, to use with factory_girl:

Factory :video_file do
  file { fixture_file_upload 'test.png', 'image/png' }

However, I ran into an issue where one of our spec’s was creating a few hundred files and would then crash with:

Errno::EMFILE: Too many open files

If you look at the source code for fixture_file_upload, it creates a new file. I don’t know if these files were being leaked, or just not getting garbage collected, but they never got closed. Eventually they just piled up and the process hit the max open file limit.

So, you need to explicitly call close on the file handle returned from fixture_file_upload. However, you can’t call close in the block immediately after fixture_file_upload because the factory needs to be able to read from the stream in order to properly initialize ‘file’.

Instead what I had to do was perform the close on the ‘proxy’ in an after_create block, like so

Factory :video_file do
  file { fixture_file_upload 'test.png', 'image/png' }

  after_create do |video, proxy|
January 30, 2012
2 thanks

Requires a Block.

Just a little heads up here because it’s not obvious.

This requires a block to be passed to it.

Example Usage

say_with_time "Reverting all service rates to nil." do
  Service.update_all( :rate, nil )

# Output
-- Reverting all service rates to nil.
   -> 0.3451s
   -> 2233 rows
January 27, 2012
0 thanks

Example Usage

End of Day for Any Date

DateTime.new( 2011, 01, 01 )
# => Sat, 01 Jan 2011 00:00:00 +0000

DateTime.new( 2011, 01, 01 ).end_of_day
# => Sat, 01 Jan 2011 23:59:59 +0000

With Local Timezone

DateTime.civil_from_format( :local, 2011, 01, 01 ).end_of_day
# => Sat, 01 Jan 2011 23:59:59 -0700
January 20, 2012 - (>= v3.0.0)
0 thanks

Stubs Logger in rspec

Let we have a module like below:

module MyModule
  class << self
    def logger
      @logger ||= Logger.new(File.join(Rails.root, "log", "my_gem_#{Rails.env}.log"))

To use this logger just type:

MyModule.logger.info "This is a log line"

To stub in tests use (for rspec):

require 'active_support/log_subscriber/test_helper'

RSpec.configure do |config|
   config.include ActiveSupport::LogSubscriber::TestHelper

   config.before do

Usefull in testing when you don’t like to log anything.

January 20, 2012
1 thank


Check if id column exists in users table

ActiveRecord::Base.connection.column_exists?(:users, :id)
January 19, 2012
1 thank

Pluralize with Text.


1 person or 3 people

Use a View Helper

pluralize( 1, 'person' )
# => 1 person

pluralize( 2, 'person' )
# => 2 people

# In practice.
pluralize( Person.count, 'person' )



January 19, 2012 - (v3.0.0 - v3.1.0)
0 thanks


I came across the following situation An article has a history of friendly url being that the foreign key that represents the value of the article’s id in the table is called Friend url_id then in that case:

Article.joins(“INNER JOIN friends ON articles.id = friends.url_id”).where(“friends.url like ? ”, url)

if the column url_id was renamed for artigo_id would be easier

Article.joins(:friend).where(“friends.url like ? ”, url)