Recent notes

RSS feed
July 29, 2011 - (v2.1.0)
0 thanks

default value for :use_full_path

FYI, It in Rails 2.1.1 the default value for :use_full_path has changed from true to false.

This will show up as an error stating “No such file or directory”

July 29, 2011
0 thanks

Basic usage

Basic usage example:

class User < ActiveRecord::Base
   skip_callback :create, :after, :send_welcome_email
July 28, 2011 - (v3.0.0 - v3.0.9)
0 thanks

sure, but what types are there to chose from?

the ‘symbol’ parameter is not something specific like ‘:after_save’, but rather ‘:save’

I suppose ‘:update’ works as well.

July 27, 2011
1 thank

includes request parameters

fullpath includes request parameters in the result

July 27, 2011 - (>= v3.0.0)
0 thanks

Multiple update, on query ?

Person.update(people.keys, people.values)

Will this request issue one or multiple queries to update the table data (as in http://stackoverflow.com/questions/3432/multiple-updates-in-mysql#3466 )

The answer is: it will do TWO queries per updated row. One select and one update.

July 15, 2011 - (v1_8_6_287 - v1_9_2_180)
1 thank

Dup vs Clone difference

As for me main difference between .dup and .clone , that first one doesn’t not freeze result object if initial object was frozen.

July 5, 2011 - (v3.0.0 - v3.0.9)
0 thanks

No way to use custom message

In what appears to be a bug, there appears to be no way to use a custom error message when using this validator.

July 2, 2011 - (<= v3.0.9)
0 thanks

Available Options and their meaning


Name of the cookie for the session


If true, session cookie is sent only to https hosts. This protects your app from session hijacking ( remember firesheep? )


Self explanatory (e.g. 60.minutes)


To which domain the cookie declares to be for

This very good post shows how to use :domain and :key to implement single-sign-on: http://itshouldbeuseful.wordpress.com/2011/02/02/rails-authlogic-and-single-sign-on/

July 1, 2011 - (>= v3.0.0)
0 thanks

Common Validator options

Most validators will support all of the following common options: (Through ActiveModel::Errors::CALLBACK_OPTIONS (http://apidock.com/rails/ActiveModel/Errors))

  • :if

  • :unless

  • :allow_blank

  • :allow_nil

July 1, 2011 - (<= v3.0.9)
0 thanks

Another way to use


link_to_unless_current("Profile", profile_path) 

%> also works (instead of pointing to controller/action)

June 29, 2011
2 thanks

Default values

For common attributes in several models, you can set a default human name like this:


    bez: Bezeichnung
    abk: Abkürzung
June 29, 2011
0 thanks

Updating nested attributes of one-to-one associations

As the documentation implicitly mentions, when updating nested attributes of a one-to-one relationship, you need to pass the ID of the nested attribute itself, otherwise a new record will be created.

This works fine:

params = { :member => { :avatar_attributes => { :id => '2', :icon => 'sad' } } }

However, the following line will build and save a new record, which is usually not what you want for one-to-one:

params = { :member => { :avatar_attributes => { :icon => 'sad' } } }

Alternatively, you can use the ‘update_only’ option. This option will ensure that an existing record will always be updated, even if the ID is not specified:

accepts_nested_attributes_for :avatar, :update_only => true
June 28, 2011 - (v3.0.9)
0 thanks

available column types

Rails 3.0.9 update for RobinWu’s post

Available column types:

:string, :text, :integer, :float, :decimal, :datetime, :timestamp, :time, :date, :binary, :boolean


MyClass < ActiveRecord::Migration

def change
  create_table :myclass do |t|
    t.string :name
    t.text :content


June 28, 2011 - (v1_9_2_180)
1 thank
June 28, 2011
0 thanks

Typo in example above

You aren’t mistaken. That is an error in the example with the block above. There’s an extra ‘(’ character.

June 24, 2011 - (v3.0.0 - v3.0.9)
1 thank

RailsCast about Responders

See Ryan Bate’s excellent RailsCast #224 about Responders in Rails 3.x: http://asciicasts.com/episodes/224-controllers-in-rails-3

June 23, 2011
0 thanks

RE: Don't Use to_formatted_s(:db) on an Array of IDs

The reason it doesnt work @joshuapinter for IDs is because if you look at the source:

case format
  when :db
    if respond_to?(:empty?) && self.empty?
      collect { |element| element.id }.join(",") # look at this line

It maps/collects the object ids and then joins them using a comma ; so in the case of 60 for instance :

60.object_id #=> 121

60.id #=> 121

June 22, 2011
1 thank

:url conflicts with :format

If you are passing both :url and :format, url overwrites the use of format, so you’ll need to pass it in the url like so:

form_for user, :url => user_path(@user, :format => :json)
June 21, 2011 - (v3.0.0 - v3.0.9)
1 thank

Clear form

for clear a form, use this:

<%= f.submit "clear", :type => "reset" %>
June 20, 2011
0 thanks

Typecasting return values

A better way to typecast the result array is to use AR’s typecasting capabilities. Example:

column = Company.columns_hash['id']
select_values("SELECT id FROM companies LIMIT 3").map do |value|
June 17, 2011
0 thanks

don't forget :root

You can rename the root tag if you don’t like what is being generated.

line_item.to_xml(:skip_instruct => true, :root => 'line-item')
June 17, 2011 - (>= v3.0.0)
0 thanks

require it

require ‘action_dispatch/testing/test_process’

June 17, 2011
0 thanks

select_values returns Strings for postgreSQL

Will return strings too when using postgreSQL and gem pg (0.11.0).

June 17, 2011
1 thank

bug's fixed, though

in 3.1.0. it works in sqlite3 even, via nested query

but 3.0.3, 3.0.7-9 all broken

June 16, 2011 - (>= v3.0.0)
1 thank

validating a database column acceptance

accept option should be set to true if you are validating a database column, since the attribute is typecast from “1” to true before validation

validates :terms,
  acceptance: {
    allow_nil: false,
    accept: true
June 15, 2011
1 thank

Unusual block calling

It is important to note that the block form of this method is unlike any other block form in Rails. You would expect this to work:

<%= f.label :terms_and_conditions do %>
  Accept <%= link_to_page 'Terms and Conditions' %>
<% end %>

But doing this ends up messing up the form (I ended up with the form repeating itself). Instead you need to do:

<%= f.label :terms_and_conditions do
  'Accept ' + link_to_page('Terms and Conditions')
end %>

Which is really only mildly better than not using the block form:

<%= f.label :terms_and_conditions,
  'Accept ' + link_to_page('Terms and Conditions') %>

You are actually better of using capture if your code lends itself to the first non-working form:

<%= f.label :terms_and_conditions, (capture do %>
  Accept <%= link_to_page 'Terms and Conditions' %>
<% end) %>

Or if you prefer brackets to parenthesis you can do:

<%= f.label :terms_and_conditions, capture { %>
  Accept <%= link_to_page 'Terms and Conditions' %>
<% } %>
June 15, 2011 - (>= v2.0.0)
1 thank
June 15, 2011
1 thank


beware, update_all silently ignores :limit and :order option in 3.0.8.

I’ve fixed my code temporarily with

update_all "foo=1 where #{myscope.where_values} limit 1"
June 14, 2011 - (>= v2.3.2)
1 thank

Set ids when using a collection of values

The trick to getting the helper to populate a unique HTML ID and for rails to recognise a collection is to give the helper a unique ‘name’ and to set the :name symbol to parameter with an array symbol ‘[]’.

<% Cars.each do |c| %>
  <%= check_box_tag "car_ids[#{c.id}]", c.id, :name => "car_ids[]" %>
<% end %>