This gem helps to encapsulate state of objects of (typically) Ruby on Rails applications.
- The state becomes easy to identify in the source code.
- There is a standard method for converting the state to and from query params.
- The state can be expressed in the form of a
cache_key
. - It is possible to additionally typecast and/or validate its attributes.
Useful for pagination, filtering etc.
Add this line to your application's Gemfile:
gem 'object_state'
And then execute:
$ bundle
Or install it yourself as:
$ gem install object_state
class MyObj
include ObjectState::Owner
object_state do
attr_accessor :current_date
end
end
my_obj.to_object_state_hash # => { my_obj => { id: "123", current_date: "2016-08-27" } }
This hash can be easily used as query params, for example:
my_obj_path(my_obj, my_obj.to_object_state_hash)
An attribute can be easily overridden:
my_obj_path(my_obj, my_obj.to_object_state_hash(current_date: Date.tomorow))
my_obj.assign_attributes_from_object_state_hash(…)
The attributes will be assigned only if the id in the state hash matches the id of your object. This is helpful for example when used in controllers.
- PoRo (
attr_accessor
) - Mongoid fields
- Virtus attributes
Optionally the state can be processed by a custom class. This is useful when the values need to be typecast, validated, or transformed. The ObjectState::State
includes ActiveModel::Model
and Virtus
so you can use Virtus' attribute definition and ActiveModel validations. For example:
class MyObj::State < ObjectState::State
attribute :current_date, Date
validates :current_date, inclusion: { in: Date.today..Date.tomorrow }, presence: true
end
Only valid values will be assigned to your object.
class MyObj
include ObjectState::Owner
object_state class_name: 'MyObj::State' do
attr_accessor :current_date
end
end
Often values or views associated with the object need to be cached (and the cache expired) depending on its state. The :object_state_cache_key
generates a cache key based on the state's values. For example the MyObj
from the above example:
my_obj.object_state_cache_key # => '2016-08-27'
In fact the object_state
method automatically merges the state object's cache key with the object's cache_key:
my_obj.cache_key # => '<object-cache-key>/2016-08-27'
This can be disabled as follows:
class MyObj
include ObjectState::Owner
object_state merge_cache_key: false do
attr_accessor :current_date
end
end
After checking out the repo, run bin/setup
to install dependencies. Then, run rake test
to run the tests. You can also run bin/console
for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install
. To release a new version, update the version number in version.rb
, and then run bundle exec rake release
, which will create a git tag for the version, push git commits and tags, and push the .gem
file to rubygems.org.
Bug reports and pull requests are welcome on GitHub at https://github.com/tomasc/object_state.
The gem is available as open source under the terms of the MIT License.