diff options
| -rw-r--r-- | guides/source/5_0_release_notes.md | 69 | ||||
| -rw-r--r-- | guides/source/caching_with_rails.md | 6 |
2 files changed, 71 insertions, 4 deletions
diff --git a/guides/source/5_0_release_notes.md b/guides/source/5_0_release_notes.md index 2c679ba632..c2d3e0aeff 100644 --- a/guides/source/5_0_release_notes.md +++ b/guides/source/5_0_release_notes.md @@ -48,7 +48,74 @@ ToDo... ### Active Record attributes API -ToDo... +Defines an attribute with a type on a model. It will override the type of existing attributes if needed. +This allows control over how values are converted to and from SQL when assigned to a model. +It also changes the behavior of values passed to ActiveRecord::Base.where, which lets use our domain objects across much of Active Record, +without having to rely on implementation details or monkey patching. + +Some things that you can achieve with this: +* The type detected by Active Record can be overridden. +* A default can also be provided. +* Attributes do not need to be backed by a database column. + +```ruby + +# db/schema.rb +create_table :store_listings, force: true do |t| + t.decimal :price_in_cents + t.string :my_string, default: "original default" +end + +# app/models/store_listing.rb +class StoreListing < ActiveRecord::Base +end + +store_listing = StoreListing.new(price_in_cents: '10.1') + +# before +store_listing.price_in_cents # => BigDecimal.new(10.1) +StoreListing.new.my_string # => "original default" + +class StoreListing < ActiveRecord::Base + attribute :price_in_cents, :integer # custom type + attribute :my_string, :string, default: "new default" # default value + attribute :my_default_proc, :datetime, default: -> { Time.now } # default value + attribute :field_without_db_column, :integer, array: true +end + +# after +store_listing.price_in_cents # => 10 +StoreListing.new.my_string # => "new default" +StoreListing.new.my_default_proc # => 2015-05-30 11:04:48 -0600 +model = StoreListing.new(field_without_db_column: ["1", "2", "3"]) +model.attributes #=> {field_without_db_column: [1, 2, 3]} +``` + +**Creating Custom Types:** + +You can define your own custom types, as long as they respond +to the methods defined on the value type. The method +deserialize+ or ++cast+ will be called on your type object, with raw input from the +database or from your controllers. This is useful, for example, when doing custom conversion, +like Money data. + +**Querying:** + +When `ActiveRecord::Base.where` is called, it will +use the type defined by the model class to convert the value to SQL, +calling +serialize+ on your type object. + +This gives the objects ability to specify, how to convert values when performing SQL queries. + +**Dirty Tracking:** + +The type of an attribute is given the opportunity to change how dirty +tracking is performed. + +See its +[documentation](http://api.rubyonrails.org/classes/ActiveRecord/Attributes/ClassMethods.html) +for a detailed write up. + ### Test Runner [Pull Request](https://github.com/rails/rails/pull/19216) diff --git a/guides/source/caching_with_rails.md b/guides/source/caching_with_rails.md index 745f09f523..6c734c1d78 100644 --- a/guides/source/caching_with_rails.md +++ b/guides/source/caching_with_rails.md @@ -100,8 +100,8 @@ called key-based expiration. Cache fragments will also be expired when the view fragment changes (e.g., the HTML in the view changes). The string of characters at the end of the key is a -template tree digest. It is an md5 hash computed based on the contents of the -view fragment you are caching. If you change the view fragment, the md5 hash +template tree digest. It is an MD5 hash computed based on the contents of the +view fragment you are caching. If you change the view fragment, the MD5 hash will change, expiring the existing file. TIP: Cache stores like Memcached will automatically delete old cache files. @@ -258,7 +258,7 @@ comment format anywhere in the template, like: If you use a helper method, for example, inside a cached block and you then update that helper, you'll have to bump the cache as well. It doesn't really matter how -you do it, but the md5 of the template file must change. One recommendation is to +you do it, but the MD5 of the template file must change. One recommendation is to simply be explicit in a comment, like: ```html+erb |