ActWithBag

In Gemfile:

gem 'act_with_bag'

Bag helps when fields in a table are not yet settled down or when many fields without business logic are required.

Install (migrate) one bag as a text field in a table to collect many fields. Additional fields or removal of them are easy; no migrations are required for them.

Keep in mind that the collection is kept in a YAML bag, i.e. SQL commands can't access the bag fields.

Boolean and Date fields require explicit typing.

Fields without typing accept any values which YAML can handle (e.g. @order.colors = ['red', 'yellow']).

Types :integer, :float and :string forces a conversion (.to_i, .to_f, .to_s) before storing the value, a convenience similar to ActiveRecord handling due to migration definitions.

Technical background: getters and putters are injected into models.

If baggies of type :date are being used then params must be corrected before an update_attributes. Warning: :date fields are not well integrated; avoid them.

Obsolete fields are deleted before_save by:

delete_from_bag :field

Warning

Please add a:

serialize :bag, Hash

to each subclass accessing a bag field from a superclass. Using an "add_to_bag" in the subclass obsoletes the "serialize".

delete_from_bag just delete the field from the record being saved. Other records are untouched, i.e. the value of the field will be kept in the database.

Example

In model:

class Order < ActiveRecord::Base
 add_to_bag :name,
  :color,
  :description,
  {idx: :integer},
  {price: :float},
  {active: :boolean},
  {paused_at: :date},
  {msg: :string}

 def to_s
  "Order #{name} #{color} #{price}"
 end
 ...

In controller:

class OrdersController < ApplicationController

 def create
  params = Order.merge({}, self.params)   # only if type :date is being used
  @order = Order.new(params[:order])
  @order.price = 1.23
  logger.info "Order #{@order.to_s} repriced to #{@order.price}"
  ...
 def update
  @order = Order.find(params[:id])
  params = Order.merge(@order.bag, self.params) # only if type :date is being used
  @order.update_attributes(params[:order])

Test

rake