kotovalexarian-likes-github/rails--rails
1
0
Fork 0
mirror of https://github.com/rails/rails.git synced 2022-11-09 12:12:34 -05:00
Code Releases Activity

Add ActiveRecord each and find_with_batches to release notes.

Browse source
This commit is contained in:
Mike Gunderloy 2009-02-23 06:37:06 -06:00
parent 8aec733048
commit 35a120d5b1
1 changed files with 24 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

26
railties/guides/source/2_3_release_notes.textile
View file

@ -42,7 +42,7 @@ Here's a summary of the rack-related changes:
h4. Renewed Support for Rails Engines
After some versions without an upgrade, Rails 2.3 offers some new features for Rails Engines (Rails applications that can be embedded within other applications). First, routing files in engines are automatically loaded and reloaded now, just like your +routes.rb+ file (this also applies to routing files in other plugins). Second, if your plugin has an app folder, then app/[models|controllers|helpers] will automatically be added to the Rails load path. Engines also support adding view paths now.
After some versions without an upgrade, Rails 2.3 offers some new features for Rails Engines (Rails applications that can be embedded within other applications). First, routing files in engines are automatically loaded and reloaded now, just like your +routes.rb+ file (this also applies to routing files in other plugins). Second, if your plugin has an app folder, then app/[models|controllers|helpers] will automatically be added to the Rails load path. Engines also support adding view paths now, and Action Mailer as well as Action View will use views from engines and other plugins.
h3. Documentation
@ -56,7 +56,7 @@ Rails 2.3 should pass all of its own tests whether you are running on Ruby 1.8 o
h3. Active Record
Active Record gets quite a number of new features and bug fixes in Rails 2.3. The highlights include nested attributes, nested transactions, dynamic scopes, and default scopes.
Active Record gets quite a number of new features and bug fixes in Rails 2.3. The highlights include nested attributes, nested transactions, dynamic and default scopes, and batch processing.
h4. Nested Attributes
@ -126,6 +126,28 @@ Rails 2.3 will introduce the notion of _default scopes_ similar to named scopes,
* Lead Contributor: Paweł Kondzior
* More Information: "What's New in Edge Rails: Default Scoping":http://ryandaigle.com/articles/2008/11/18/what-s-new-in-edge-rails-default-scoping
h4. Batch Processing
You can now process large numbers of records from an ActiveRecord model with less pressure on memory by using +find_in_batches+:
<ruby>
Customer.find_in_batches(:conditions => {:active => true}) do |customer_group|
customer_group.each { |customer| customer.update_account_balance! }
end
</ruby>
You can pass most of the +find+ options into +find_in_batches+. However, you cannot specify the order that records will be returned in (they will always be returned in ascending order of primary key, which must be an integer), or use the +:limit+ option. Instead, use the +:batch_size: option, which defaults to 1000, to set the number of records that will be returned in each batch.
The new +each+ method provides a wrapper around +find_in_batches+ that returns individual records, with the find itself being done in batches (of 1000 by default):
<ruby>
Customer.each do |customer|
customer.update_account_balance!
end
</ruby>
Note that you should only use this record for batch processing: for small numbers of records (less than 1000), you should just use the regular find methods with your own loop.
h4. Multiple Conditions for Callbacks
When using Active Record callbacks, you can now combine +:if+ and +:unless+ options on the same callback, and supply multiple conditions as an array: