EntitySchema

Class-level DSL for mapping Hash with object-like structure to Object (as Entity), and then return it into Hash.

class Product
  property  :id
  property  :title
  property? :enabled
  property? :new,        key: :is_new
  property? :sale,       key: :is_sale
  property? :bestseller, key: :is_bestseller
  timestamps

  object :size, map_to: Values::Size

  belongs_to :color,   Color, pk: :color_uid, fk: :uid
  has_many   :seasons, Season
end

Motivation

When you work with plain hashes (Sequel, ROM, json/xml-sourced data, etc), and want to describe some entities or value objects (DDD patterns).

Ok, if ROM, why not ROM::Struct?

If you using ROM with it's ROM::Struct, you may encounter some things that do not satisfy some needs: private attributes, value object mapping, may be something other.

Installation

in Gemfile add

gem 'entity_schema'

Usage

Create entity from hash:

raw_hash = {
  id: 42,
  title: 'Perfect product',
  enabled: true,
  is_new: false,
  is_sale: false,
  is_bestseller: true,
  created_at: '2018-08-16 20:17:55 UTC',
  updated_at: '2018-08-16 20:17:55 UTC',
  size: { ... size params ... },
  color_uid: 7,
  seasons: [{ ... season params ... }, {...}, ...]
}

product = Product.new(raw_hash)
product.title
product.sale?
product.size            # => <Values::Size ... >
product.seasons         # => [<Season ... >, <Season ... >, ...]

product.color           # => <Color @uid=7 ... >
product.color_uid       # => 7
product.color = nil     # => nil
product.color_uid       # => nil

Return entity to hash:

product.to_h # =>
  {
    id: 42,
    title: 'Perfect product',
    enabled: true,
    is_new: false,
    is_sale: false,
    is_bestseller: true,
    created_at: '2018-08-16 20:17:55 UTC',
    updated_at: '2018-08-16 20:17:55 UTC',
    size: { ... size params ... },
    color_uid: nil,
    seasons: [{ ... seasons params ... }, {...}, ...]
  }

Validations, and coercions

No. Entity assumes that given data already validated and coerced.

DSL

property

TODO: description

property?

TODO: description

timestamps

Just sugar, same as:

property :created_at, private: :setter, **opts
property :updated_at, private: :setter, **opts

object

TODO: description

collection

TODO: description

has_one

Just alias for object

has_many

Just alias for collection

belongs_to

TODO: description

Instance methods

TODO: description