serialized_attributes
This is a very cool lib, allows to define dynamic serialized fields in your AR model, which acts as normal rails db columns. It give you full power of rails to your virtual columns: validations, rails forms, error messages, type casting (integer, date/time), type safety, :dirty? s, etc.. STI is supported! Basic associations is working too!
Now updated for Rails 3
Example of usage
STI table def
create_table :documents do |t|
t.string :type
t.text :serialized_attributes # <--- here all your dynamic fields will be saved
t.integer :reference_id # <--- you can also define any sql columns for your indexes
t.timestamps
end
STI base model
class Document < ActiveRecord::Base
include SerializedAttributes
end
Other models..
class Post < Document
attribute :title, String
attribute :body, String
attribute :is_published, Boolean, :default => false
attribute :comment_ids, Array # <--- serialized Array of ids of associated comments
has_references_to :comments
validates_presence_of :title, :body
end
class Comment < Document
attribute :body, String, :requied => true # <--- validates_presence_of :body
attribute :post_id, Integer
belongs_to :post
end
IRB fun
post = Post.create(:title => "First Post", :body => "Lorem ...")
assert !post.new_record?
post.comments = [Comment.create(:body => "this is a comment")]
post.comments << Comment.create(:body => "this is second comment")
assert_equal Comment.all.map(&:id), post.comment_ids
post.save
assert post.reload.comments.length == 2
Mass Assignment and Protect Attributes
class Widget < ActiveRecord::Base
include SerializedAttributes
#protect other attributes from mass assignment
attr_accessible :name
#specifically permit a given serialized attribute to be mass assigned
accessible_attribute :creator, String
end
limitations
- has-references-to association dont update reverse association
- serialized-attributes column saved every time you call :save without depending on what is actually changed