This post originated from an RSS feed registered with Ruby Buzz by rwdaigle. Original Post: What's New in Edge Rails: Partial Updates Feed Title: Ryan's Scraps Feed URL: http://feeds.feedburner.com/RyansScraps Feed Description: Ryan Daigle's various technically inclined rants along w/ the "What's new in Edge Rails" series. Latest Ruby Buzz Posts Latest Ruby Buzz Posts by rwdaigle Latest Posts From Ryan's Scraps

In lock-step with the recent dirty objects functionality comes the ability of ActiveRecord models to perform partial updates – which only saves the attributes that have been modified on updates.

For instance:

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article = Article.find(:first)
article.title  #=> "Title"
article.subject  #=> "Edge Rails"

# Update one of the attributes
article.title = "New Title"

# And only that updated attribute is persisted to the db
article.save
  #=>  "UPDATE articles SET title = 'New Title' WHERE id = 1"

Note: Your updated_at/on magic fields will only be set if there are unsaved attributes that need persisting. If there are no changed attributes for the object being persisted then there won’t be any SQL updates made.

To enable this functionality, set partial_updates = true for each model you wish to take advantage of partial updates. To enable this system-wide add this line to your environment.rb or, better yet, in a config/initializer:

ActiveRecord::Base.partial_updates = true

Note: There’s currently a config/initializers/new_rails_defaults.rb file that has this setting, so edit that file if you have it.

tags: ruby, rubyonrails