Declarative

DSL for nested schemas.

Overview

Declarative allows declaring nested schemas.

Installation

Add this line to your application's Gemfile:

gem 'declarative'

Declarative::Schema

Include this into a class or module to allow defining nested schemas using the popular ::property DSL.

Normally, an abstract base class will define essential configuration.

class Model
 extend Declarative::Schema

  def self.default_nested_class
    Model
  end
end

Concrete schema-users simply derive from the base class.

class Song < Model
  property :id

  property :artist do
    property :id
    property :name
  end
end

This won't do anything but populate the ::definitions graph.

Song.definitions #=>

<Definition "id">
<Definition "artist" nested=..>
  <Definition "id">
  <Definition "name">

The nested schema will be a subclass of Model.

Song.definitions.get(:artist) #=> <Anonymous:Model definitions=..>

Overriding Nested Building

When declaring nested schemas, per default, Declarative will use its own Schema::NestedBuilder to create the nested schema composer.

Override ::nested_builder to define your own way of doing that.

class Model
  extend Declarative::Schema

  def self.default_nested_class
    Model
  end

  def self.nested_builder
    ->(options) do
      Class.new(Model) do
        class_eval &options[:_block] # executes `property :name` etc. on nested, fresh class.
      end
    end
  end
end

Features

You can automatically include modules into all nested schemas by using ::feature.

class Model
  extend Declarative::Schema
  feature Bla

Defaults

class Model
  extend Declarative::Schema
  defaults visible: true