Virtus::Relations
Adds relations to Virtus objects.
Installation
In your Gemfile:
gem 'virtus-relations'In your source code:
require 'virtus/relations'Usage examples
Given the following classes:
require 'virtus/relations'
class Kid
include Virtus.model
attribute :name, String
end
class Mother
include Virtus.model
include Virtus.relations(as: :mom)
attribute :name, String
attribute :kid, Kid, relation: true, lazy: true, default: :load_kid
def load_kid
{ name: 'Billy' }
end
endYou can do the following:
### Explicit assignment
alice = Mother.new(name: 'Alice')
alice.kid = { name: 'Danny' }
alice.kid.mom
# => <Mother:0x007fa43415fda8 @name="Alice", ...>
### Mass-assignment
emma = Mother.new(name: 'Emma', kid: { name: 'Johnny' })
emma.kid.mom
# => #<Mother:0x007fc40dbbdbf8 @name="Emma", ...>
### Lazy assignment
mia = Mother.new(name: 'Mia')
mia.kid.mom
# => #<Mother:0x007fa435d27130 @name="Mia", ...>
### Objects can still be created without a parent
orphan = Kid.new(name: 'Deirdre')
orphan.mom
# => NoMethodError: undefined method `mom' for #<Kid:0x007...The :as option defaults to :parent when omitted
Why relations?
Although regular attributes could be used to mimic this behavior, using relations can have two key benefits:
- It does not create circular dependencies (known to cause issues with serializers)
- It allows polymorphic relations (e.g. an Address can belong to either a User, or a Company)
Contributing
- Fork it
- Create your feature branch
- Comply with the ruby style guide
- Add tests for your new feature/bugfix. This is important so I don't break it in a future version unintentionally.
- Submit a pull request