Notes

This doesn't work for me. I do something like:

create_table :user_follows, :force => true do |t|
  t.references :user
  t.references :followed_user
  t.timestamps
  t.index :user
  t.index :followed_user
end

and I get:

rake aborted!
An error has occurred, all l...

One undocumented feature, you can do this: person = Person.first Person.exists?(person) # => returns true This came in handy for me when I needed to see if something belonged to a particular scope.

scope = "created_rails"
person = Person.find_by_name "dhh"
Person.send(scope)...

==== Code example date_from = Date.new(2010, 9, 11) #<Date: 4910901/2,0,2299161> date_till = Date.new(2010, 11, 12) #<Date: 4911025/2,0,2299161> rational_offset = (date_till - date_from) #Rational62, 1 rational_offset.to_i #62

:as is a good but poorly document argument to rendering a collection:

<%= render :partial => 'some_partial', :collection => an_array, :as => :better_name -%>

Which will give you each element of +an_array+ in the partial in a local variable named +better_name+ not +some_partial+.

To set the hour and/or the minutes, you can use:

<%= f.datetime_select(:offer_end, :default => { :hour => 23, :minute => 59 }) %>

Support for the +:inverse_of+ option was backported to 2.3.6+.

Here's the description from the original commit: http://github.com/rails/rails/commit/ccea98389abbf150b886c9f964b1def47f00f237

You can now add an :inverse_of option to has_one, has_many and belongs_to associations. This is best de...

Support for the +:inverse_of+ option was backported to 2.3.6+.

Here's the description from the original commit: http://github.com/rails/rails/commit/ccea98389abbf150b886c9f964b1def47f00f237

You can now add an :inverse_of option to has_one, has_many and belongs_to associations. This is best de...

Support for the +:inverse_of+ option was backported to 2.3.6+.

Here's the description from the original commit: http://github.com/rails/rails/commit/ccea98389abbf150b886c9f964b1def47f00f237

You can now add an :inverse_of option to has_one, has_many and belongs_to associations. This is best de...

When creating a parent and its children using nested attributes, you can use the +:inverse_of+ option on the association to correctly set the parent back references:

class Parent < ActiveRecord::Base
has_many :children, :inverse_of => :parent
accepts_nested_attributes_for :children...

Instead of using:

session.delete

Now use:

reset_session

Nice one, henning. For anyone using Rails (ActiveSupport) a handy method called #from is also present.

[1, 2, 3, 4, 5].from(2) # => [3, 4, 5]

So our example would be

a.from(i)

It reads a lot better

If you use update_all to change an attribute marked as serialized ( using ActiveRecord::Base.serialize ), you need to call to_yaml yourself:

User.update_all({ :preferences => { :first_name => 'John', :last_name => 'Doe' }.to_yaml })

use model_instance.errors[:base] << "Msg" instead of depracated model_instance.errors.add_to_base("Msg") for Rails 3

use model_instance.errors[:base] << "Msg" instead of depracated model_instance.errors.add_to_base("Msg") for Rails 3

If you do a single Rails.cache.read('my_key'), your will usually see in your log something like

Cache read: my_key
Cache read: my_key
Cache write: my_key

Don't worry about this.

What happens here is this: Before going to memcached, rails will first ask a local MemoryStore...