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shale

0.15
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Ruby object mapper and serializer for XML, JSON, TOML, CSV and YAML.
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 Project Readme

Shale

Shale is a Ruby object mapper and serializer for JSON, YAML, TOML, CSV and XML. It allows you to parse JSON, YAML, TOML, CSV and XML data and convert it into Ruby data structures, as well as serialize data structures into JSON, YAML, TOML, CSV or XML.

Documentation with interactive examples is available at Shale website

Features

  • Convert JSON, YAML, TOML, CSV and XML to Ruby data model
  • Convert Ruby data model to JSON, YAML, TOML, CSV and XML
  • Generate JSON and XML Schema from Ruby models
  • Compile JSON and XML Schema into Ruby models
  • Out of the box support for JSON, YAML, Tomlib, toml-rb, CSV, Nokogiri, REXML and Ox parsers
  • Support for custom adapters

Installation

Shale supports Ruby (MRI) 2.6+

Add this line to your application's Gemfile:

gem 'shale'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install shale

Contents

  • Simple use case
  • Creating objects
  • Converting JSON to object
  • Converting object to JSON
  • Converting YAML to object
  • Converting object to YAML
  • Converting TOML to object
  • Converting object to TOML
  • Converting Hash to object
  • Converting object to Hash
  • Converting XML to object
  • Converting object to XML
  • Converting CSV to object
  • Converting object to CSV
  • Converting collections
  • Mapping JSON keys to object attributes
  • Mapping YAML keys to object attributes
  • Mapping TOML keys to object attributes
  • Mapping CSV columns to object attributes
  • Mapping Hash keys to object attributes
  • Mapping XML elements and attributes to object attributes
  • Using XML namespaces
  • Rendering nil values
  • Using methods to extract and generate data
  • Delegating fields to child attributes
  • Additional options
  • Using custom models
  • Supported types
  • Writing your own type
  • Adapters
  • Generating JSON Schema
  • Compiling JSON Schema into Shale model
  • Generating XML Schema
  • Compiling XML Schema into Shale model

Usage

Simple use case

require 'shale'

class Address < Shale::Mapper
  attribute :city, Shale::Type::String
  attribute :street, Shale::Type::String
  attribute :zip, Shale::Type::String
end

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String
  attribute :age, Shale::Type::Integer
  attribute :married, Shale::Type::Boolean, default: -> { false }
  attribute :hobbies, Shale::Type::String, collection: true
  attribute :address, Address
end
  • default: -> { 'value' } - add a default value to attribute (it must be a proc that returns value)
  • collection: true - indicates that a attribute is a collection

Creating objects

person = Person.new(
  first_name: 'John',
  last_name: 'Doe',
  age: 50,
  hobbies: ['Singing', 'Dancing'],
  address: Address.new(city: 'London', street: 'Oxford Street', zip: 'E1 6AN'),
)

Converting JSON to object

person = Person.from_json(<<~DATA)
{
  "first_name": "John",
  "last_name": "Doe",
  "age": 50,
  "married": false,
  "hobbies": ["Singing", "Dancing"],
  "address": {
    "city": "London",
    "street": "Oxford Street",
    "zip": "E1 6AN"
  }
}
DATA

# =>
#
# #<Person:0x00007f9bc3086d60
#  @address=
#   #<Address:0x00007f9bc3086748
#    @city="London",
#    @street="Oxford Street",
#    @zip="E1 6AN">,
#  @age=50,
#  @first_name="John",
#  @hobbies=["Singing", "Dancing"],
#  @last_name="Doe",
#  @married=false>

Converting object to JSON

person.to_json

# =>
#
# {
#   "first_name": "John",
#   "last_name": "Doe",
#   "age": 50,
#   "married": false,
#   "hobbies": ["Singing", "Dancing"],
#   "address": {
#     "city": "London",
#     "street": "Oxford Street",
#     "zip": "E1 6AN"
#   }
# }

Converting YAML to object

person = Person.from_yaml(<<~DATA)
first_name: John
last_name: Doe
age: 50
married: false
hobbies:
- Singing
- Dancing
address:
  city: London
  street: Oxford Street
  zip: E1 6AN
DATA

Converting object to YAML

person.to_yaml

# =>
#
# ---
# first_name: John
# last_name: Doe
# age: 50
# married: false
# hobbies:
# - Singing
# - Dancing
# address:
#   city: London
#   street: Oxford Street
#   zip: E1 6AN

Converting TOML to object

To use TOML with Shale you have to set adapter you want to use. Out of the box Shale suports Tomlib. It also comes with adapter for toml-rb if you prefer that. For details see Adapters section.

To set it, first make sure Tomlib gem is installed:

$ gem install tomlib

then setup adapter:

require 'tomlib'
Shale.toml_adapter = Tomlib

# Alternatively if you'd like to use toml-rb, use:
require 'shale/adapter/toml_rb'
Shale.toml_adapter = Shale::Adapter::TomlRB

Now you can use TOML with Shale:

person = Person.from_toml(<<~DATA)
first_name = "John"
last_name = "Doe"
age = 50
married = false
hobbies = ["Singing", "Dancing"]
[address]
city = "London"
street = "Oxford Street"
zip = "E1 6AN"
DATA

Converting object to TOML

person.to_toml

# =>
#
# first_name = "John"
# last_name = "Doe"
# age = 50
# married = false
# hobbies = [ "Singing", "Dancing" ]
#
# [address]
# city = "London"
# street = "Oxford Street"
# zip = "E1 6AN"

Converting Hash to object

person = Person.from_hash(
  'first_name' => 'John',
  'last_name' => 'Doe',
  'age' => 50,
  'married' => false,
  'hobbies' => ['Singing', 'Dancing'],
  'address' => {
    'city'=>'London',
    'street'=>'Oxford Street',
    'zip'=>'E1 6AN'
  },
)

Converting object to Hash

person.to_hash

# =>
#
# {
#   "first_name"=>"John",
#   "last_name"=>"Doe",
#   "age"=>50,
#   "married"=>false,
#   "hobbies"=>["Singing", "Dancing"],
#   "address"=>{"city"=>"London", "street"=>"Oxford Street", "zip"=>"E1 6AN"}
# }

Converting XML to object

To use XML with Shale you have to set adapter you want to use. Shale comes with adapters for REXML, Nokogiri and OX parsers. For details see Adapters section.

require 'shale/adapter/rexml'
Shale.xml_adapter = Shale::Adapter::REXML

Now you can use XML with Shale:

person = Person.from_xml(<<~DATA)
<person>
  <first_name>John</first_name>
  <last_name>Doe</last_name>
  <age>50</age>
  <married>false</married>
  <hobbies>Singing</hobbies>
  <hobbies>Dancing</hobbies>
  <address>
    <city>London</city>
    <street>Oxford Street</street>
    <zip>E1 6AN</zip>
  </address>
</person>
DATA

Converting object to XML

person.to_xml

# =>
#
# <person>
#   <first_name>John</first_name>
#   <last_name>Doe</last_name>
#   <age>50</age>
#   <married>false</married>
#   <hobbies>Singing</hobbies>
#   <hobbies>Dancing</hobbies>
#   <address>
#     <city>London</city>
#     <street>Oxford Street</street>
#     <zip>E1 6AN</zip>
#   </address>
# </person>

Converting CSV to object

CSV represents a flat data structure, so you can't map properties to complex types directly, but you can use methods to map properties to complex types (see Using methods to extract and generate data section).

.from_csv method allways returns an array of records.

people = Person.from_csv(<<~DATA)
John,Doe,50,false
DATA

Converting object to CSV

people[0].to_csv # or Person.to_csv(people) if you want to convert a collection

# =>
#
# John,Doe,50,false

Converting collections

Shale allows converting collections for formats that support it (JSON, YAML and CSV). To convert Ruby array to JSON:

person1 = Person.new(name: 'John Doe')
person2 = Person.new(name: 'Joe Sixpack')

Person.to_json([person1, person2], pretty: true)
# or Person.to_yaml([person1, person2])
# or Person.to_csv([person1, person2])

# =>
#
# [
#   { "name": "John Doe" },
#   { "name": "Joe Sixpack" }
# ]

To convert JSON array to Ruby:

Person.from_json(<<~JSON)
[
  { "name": "John Doe" },
  { "name": "Joe Sixpack" }
]
JSON

# =>
#
# [
#   #<Person:0x00000001033dbce8 @name="John Doe">,
#   #<Person:0x00000001033db4c8 @name="Joe Sixpack">
# ]

Mapping JSON keys to object attributes

By default keys are named the same as attributes. To use custom keys use:

⚠️ Declaring custom mapping removes default mapping for given format!

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String

  json do
    map 'firstName', to: :first_name
    map 'lastName', to: :last_name
  end
end

Mapping YAML keys to object attributes

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String

  yaml do
    map 'firstName', to: :first_name
    map 'lastName', to: :last_name
  end
end

Mapping TOML keys to object attributes

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String

  toml do
    map 'firstName', to: :first_name
    map 'lastName', to: :last_name
  end
end

Mapping CSV columns to object attributes

For CSV the order of mapping matters, the first argument in the map method is only used as a label in header row. So, in the example below the first column will be mapped to :first_name attribute and the second column to :last_name.

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String

  csv do
    map 'firstName', to: :first_name
    map 'lastName', to: :last_name
  end
end

Mapping Hash keys to object attributes

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String

  hsh do
    map 'firstName', to: :first_name
    map 'lastName', to: :last_name
  end
end

Mapping XML elements and attributes to object attributes

XML is more complicated format than JSON or YAML. To map elements, attributes and content use:

class Address < Shale::Mapper
  attribute :street, Shale::Type::String
  attribute :city, Shale::Type::String
  attribute :zip, Shale::Type::String

  xml do
    map_content to: :street
    map_element 'City', to: :city
    map_element 'ZIP', to: :zip
  end
end

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String
  attribute :age, Shale::Type::Integer
  attribute :hobbies, Shale::Type::String, collection: true
  attribute :address, Address

  xml do
    root 'Person'

    map_attribute 'age', to: :age

    map_element 'FirstName', to: :first_name
    map_element 'LastName', to: :last_name
    map_element 'Hobby', to: :hobbies
    map_element 'Address', to: :address
  end
end

person = Person.from_xml(<<~DATA)
<Person age="50">
  <FirstName>John</FirstName>
  <LastName>Doe</LastName>
  <Hobby>Singing</Hobby>
  <Hobby>Dancing</Hobby>
  <Address>
    Oxford Street
    <City>London</City>
    <ZIP>E1 6AN</ZIP>
  </Address>
</person>
DATA
  • root - name of the root element
  • map_element - map content of element to attribute
  • map_attribute - map element's attribute to attribute
  • map_content - map first text node to attribute

You can use cdata: true option on map_element and map_content to handle CDATA nodes:

class Address < Shale::Mapper
  attribute :content, Shale::Type::String

  xml do
    map_content to: :content, cdata: true
  end
end

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :address, Address

  xml do
    root 'Person'

    map_element 'FirstName', to: :first_name, cdata: true
    map_element 'Address', to: :address
  end
end

person = Person.from_xml(<<~DATA)
<Person>
  <FirstName><![CDATA[John]]></FirstName>
  <Address><![CDATA[Oxford Street]]></Address>
</person>
DATA

Using XML namespaces

To map namespaced elements and attributes use namespace and prefix properties on map_element and map_attribute

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String
  attribute :age, Shale::Type::Integer

  xml do
    root 'person'

    map_element 'first_name', to: :first_name, namespace: 'http://ns1.com', prefix: 'ns1'
    map_element 'last_name', to: :last_name, namespace: 'http://ns2.com', prefix: 'ns2'
    map_attribute 'age', to: :age, namespace: 'http://ns2.com', prefix: 'ns2'
  end
end

person = Person.from_xml(<<~DATA)
<person xmlns:ns1="http://ns1.com" xmlns:ns2="http://ns2.com" ns2:age="50">
  <ns1:first_name>John</ns1:first_name>
  <ns2:last_name>Doe</ns2:last_name>
</person>
DATA

To define default namespace for all elements use namespace declaration (this will define namespace on elements only, if you want to define namespace on an attribute explicitly declare it on map_attribute).

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :middle_name, Shale::Type::String
  attribute :last_name, Shale::Type::String
  attribute :age, Shale::Type::Integer
  attribute :hobby, Shale::Type::String

  xml do
    root 'person'
    namespace 'http://ns1.com', 'ns1'

    map_element 'first_name', to: :first_name

    # undeclare namespace on 'middle_name' element
    map_element 'middle_name', to: :middle_name, namespace: nil, prefix: nil

    # overwrite default namespace
    map_element 'last_name', to: :last_name, namespace: 'http://ns2.com', prefix: 'ns2'

    map_attribute 'age', to: :age
    map_attribute 'hobby', to: :hobby, namespace: 'http://ns1.com', prefix: 'ns1'
  end
end

person = Person.from_xml(<<~DATA)
<ns1:person xmlns:ns1="http://ns1.com" xmlns:ns2="http://ns2.com" age="50" ns1:hobby="running">
  <ns1:first_name>John</ns1:first_name>
  <middle_name>Joe</middle_name>
  <ns2:last_name>Doe</ns2:last_name>
</ns1:person>
DATA

Rendering nil values

For JSON, YAML, TOML and XML by default, elements with nil value are not rendered. You can change this behavior by using render_nil: true on a mapping. For CSV the default is to render nil elements.

class Person < Shale::Mapper
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String
  attribute :age, Shale::Type::Integer

  json do
    map 'first_name', to: :first_name, render_nil: true
    map 'last_name', to: :last_name, render_nil: false
    map 'age', to: :age, render_nil: true
  end

  xml do
    root 'person'

    map_element 'first_name', to: :first_name, render_nil: true
    map_element 'last_name', to: :last_name, render_nil: false
    map_attribute 'age', to: :age, render_nil: true
  end
end

person = Person.new(first_name: nil, last_name: nil, age: nil)

puts person.to_json(pretty: true)

# =>
#
# {
#   "first_name": null,
#   "age": "null"
# }

puts person.to_xml(pretty: true)

# =>
#
# <person age="">
#   <first_name/>
# </person>

Using methods to extract and generate data

If you need full controll over extracting and generating data from/to document, you can use methods to do so:

class Person < Shale::Mapper
  attribute :hobbies, Shale::Type::String, collection: true
  attribute :street, Shale::Type::String
  attribute :city, Shale::Type::String

  json do
    map 'hobbies', using: { from: :hobbies_from_json, to: :hobbies_to_json }
    map 'address', using: { from: :address_from_json, to: :address_to_json }
  end

  xml do
    root 'Person'

    map_attribute 'hobbies', using: { from: :hobbies_from_xml, to: :hobbies_to_xml }
    map_element 'Address', using: { from: :address_from_xml, to: :address_to_xml }
  end

  def hobbies_from_json(model, value)
    model.hobbies = value.split(',').map(&:strip)
  end

  def hobbies_to_json(model, doc)
    doc['hobbies'] = model.hobbies.join(', ')
  end

  def address_from_json(model, value)
    model.street = value['street']
    model.city = value['city']
  end

  def address_to_json(model, doc)
    doc['address'] = { 'street' => model.street, 'city' => model.city }
  end

  def hobbies_from_xml(model, value)
    model.hobbies = value.split(',').map(&:strip)
  end

  def hobbies_to_xml(model, element, doc)
    doc.add_attribute(element, 'hobbies', model.hobbies.join(', '))
  end

  def address_from_xml(model, node)
    model.street = node.children.find { |e| e.name == 'Street' }.text
    model.city = node.children.find { |e| e.name == 'City' }.text
  end

  def address_to_xml(model, parent, doc)
    street_element = doc.create_element('Street')
    doc.add_text(street_element, model.street.to_s)

    city_element = doc.create_element('City')
    doc.add_text(city_element, model.city.to_s)

    address_element = doc.create_element('Address')
    doc.add_element(address_element, street_element)
    doc.add_element(address_element, city_element)
    doc.add_element(parent, address_element)
  end
end

person = Person.from_json(<<~DATA)
{
  "hobbies": "Singing, Dancing, Running",
  "address": {
    "street": "Oxford Street",
    "city": "London"
  }
}
DATA

person = Person.from_xml(<<~DATA)
<Person hobbies="Singing, Dancing, Running">
  <Address>
    <Street>Oxford Street</Street>
    <City>London</City>
  </Address>
</Person>
DATA

# =>
#
# #<Person:0x00007f9bc3086d60
#  @hobbies=["Singing", "Dancing", "Running"],
#  @street="Oxford Street",
#  @city="London">

You can also pass a context object that will be available in extractor/generator methods:

class Person < Shale::Mapper
  attribute :password, Shale::Type::String

  json do
    map 'password', using: { from: :password_from_json, to: :password_to_json }
  end

  def password_from_json(model, value, context)
    if context.admin?
      model.password = value
    else
      model.password = '*****'
    end
  end

  def password_to_json(model, doc, context)
    if context.admin?
      doc['password'] = model.password
    else
      doc['password'] = '*****'
    end
  end
end

Person.new(password: 'secret').to_json(context: current_user)

If you want to work on multiple elements at a time you can group them using group block:

class Person < Shale::Mapper
  attribute :name, Shale::Type::String

  json do
    group from: :name_from_json, to: :name_to_json do
      map 'first_name'
      map 'last_name'
    end
  end

  xml do
    group from: :name_from_xml, to: :name_to_xml do
      map_content
      map_element 'first_name'
      map_attribute 'last_name'
    end
  end

  def name_from_json(model, value)
    model.name = "#{value['first_name']} #{value['last_name']}"
  end

  def name_to_json(model, doc)
    doc['first_name'] = model.name.split(' ')[0]
    doc['last_name'] = model.name.split(' ')[1]
  end

  def name_from_xml(model, value)
    # value => { content: ..., attributes: {}, elements: {} }
  end

  def name_to_xml(model, element, doc)
    # ...
  end
end

Person.from_json(<<~DATA)
{
  "first_name": "John",
  "last_name": "Doe"
}
DATA

# => #<Person:0x00007f9bc3086d60 @name="John Doe">

Delegating fields to child attributes

To delegate fields to child complex types you can use receiver: :child declaration:

class Address < Shale::Mapper
  attribute :city, Shale::Type::String
  attribute :street, Shale::Type::String
end

class Person < Shale::Mapper
  attribute :name, Shale::Type::String
  attribute :address, Address

  json do
    map 'name', to: :name
    map 'city', to: :city, receiver: :address
    map 'street', to: :street, receiver: :address
  end
end

person = Person.from_json(<<~DATA)
{
  "name": "John Doe",
  "city": "London",
  "street": "Oxford Street"
}
DATA

# =>
#
# #<Person:0x00007f9bc3086d60
#  @name="John Doe",
#  @address=#<Address:0x0000000102cbd218 @city="London", @street="Oxford Street">>

Additional options

You can control which attributes to render and parse by using only: [] and except: [] parameters.

# e.g. if you have this model graph:
person = Person.new(
  first_name: 'John'
  last_name: 'Doe',
  address: Address.new(city: 'London', street: 'Oxford Street')
)

# if you want to render only `first_name` and `address.city` do:
person.to_json(only: [:first_name, address: [:city]], pretty: true)

# =>
#
# {
#   "first_name": "John",
#   "address": {
#     "city": "London"
#   }
# }

# and if you don't need an address you can do:
person.to_json(except: [:address], pretty: true)

# =>
#
# {
#   "first_name": "John",
#   "last_name": "Doe"
# }

It works the same for parsing:

# e.g. if you want to parse only `address.city` do:
Person.from_json(doc, only: [address: [:city]])

# =>
#
# #<Person:0x0000000113d7a488
#  @first_name=nil,
#  @last_name=nil,
#  @address=#<Address:0x0000000113d7a140 @street=nil, @city="London">>

# and if you don't need an `address`:
Person.from_json(doc, except: [:address])

# =>
#
# #<Person:0x0000000113d7a488
#  @first_name="John",
#  @last_name="Doe",
#  @address=nil>

If you need formatted output you can pass pretty: true parameter to #to_json and #to_xml

person.to_json(pretty: true)

# =>
#
# {
#   "name": "John Doe",
#   "address": {
#     "city": "London"
#   }
# }

You can also add an XML declaration by passing declaration: true and encoding: true or if you want to spcify version: declaration: '1.1' and encoding: 'ASCII' to #to_xml

person.to_xml(pretty: true, declaration: true, encoding: true)

# =>
#
# <?xml version="1.0" encoding="UTF-8"?>
# <Person>
#   <Address city="London"/>
# </Person>

For CSV you can pass headers: true to indicate that the first row contains column names and shouldn't be included in the returned collection. It also accepts all the options that CSV parser accepts.

class Person
  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String
end

people = Person.from_csv(<<~DATA, headers: true, col_sep: '|')
  first_name|last_name
  John|Doe
  James|Sixpack
DATA

# =>
#
# [
#   #<Person:0x0000000113d7a488 @first_name="John", @last_name="Doe">,
#   #<Person:0x0000000113d7a488 @first_name="James", @last_name="Sixpack">
# ]

Person.to_csv(people, headers: true, col_sep: '|')

# =>
#
# first_name|last_name
# John|Doe
# James|Sixpack

Using custom models

By default Shale combines mapper and model into one class. If you want to use your own classes as models you can do it by using model directive on the mapper:

class Address
  attr_accessor :street, :city
end

class Person
  attr_accessor :first_name, :last_name, :address
end

class AddressMapper < Shale::Mapper
  model Address

  attribute :street, Shale::Type::String
  attribute :city, Shale::Type::String
end

class PersonMapper < Shale::Mapper
  model Person

  attribute :first_name, Shale::Type::String
  attribute :last_name, Shale::Type::String
  attribute :address, AddressMapper
end

person = PersonMapper.from_json(<<~DATA)
{
  "first_name": "John",
  "last_name": "Doe",
  "address": {
    "street": "Oxford Street",
    "city": "London"
  }
}
DATA

# =>
#
# #<Person:0x0000000113d7a488
#  @first_name="John",
#  @last_name="Doe",
#  @address=#<Address:0x0000000113d7a140 @street="Oxford Street", @city="London">>

PersonMapper.to_json(person, pretty: true)

# =>
#
# {
#   "first_name": "John",
#   "last_name": "Doe",
#   "address": {
#     "street": "Oxford Street",
#     "city": "London"
#   }
# }

Supported types

Shale supports these types out of the box:

  • Shale::Type::Boolean
  • Shale::Type::Date
  • Shale::Type::Float
  • Shale::Type::Integer
  • Shale::Type::String
  • Shale::Type::Time

Writing your own type

To add your own type extend it from Shale::Type::Value and implement .cast class method.

require 'shale/type/value'

class MyIntegerType < Shale::Type::Value
  def self.cast(value)
    value.to_i
  end
end

Adapters

Shale uses adapters for parsing and generating documents. By default Ruby's standard JSON, YAML, CSV parsers are used for handling JSON YAML, CSV documents.

You can change it by providing your own adapter. For JSON, YAML, TOML and CSV adapter must implement .load and .dump class methods.

require 'shale'
require 'multi_json'

Shale.json_adapter = MultiJson
Shale.yaml_adapter = MyYamlAdapter

To handle TOML documents you have to set TOML adapter. Out of the box Tomlib is supported. Shale also provides adapter for toml-rb parser:

require 'shale'

# if you want to use Tomlib
require 'tomlib'
Shale.toml_adapter = Tomlib

# if you want to use toml-rb
require 'shale/adapter/toml_rb'
Shale.toml_adapter = Shale::Adapter::TomlRB

To handle XML documents you have to explicitly set XML adapter. Shale provides adapters for most popular Ruby XML parsers:

⚠️ Ox doesn't support XML namespaces

require 'shale'

# if you want to use REXML:

require 'shale/adapter/rexml'
Shale.xml_adapter = Shale::Adapter::REXML

# if you want to use Nokogiri:

require 'shale/adapter/nokogiri'
Shale.xml_adapter = Shale::Adapter::Nokogiri

# or if you want to use Ox:

require 'shale/adapter/ox'
Shale.xml_adapter = Shale::Adapter::Ox

Generating JSON Schema

⚠️ Only Draft 2020-12 JSON Schema is supported

To generate JSON Schema from your Shale data model use:

require 'shale/schema'

Shale::Schema.to_json(
  Person,
  id: 'http://foo.bar/schema/person',
  description: 'My description',
  pretty: true
)

# =>
#
# {
#   "$schema": "https://json-schema.org/draft/2020-12/schema",
#   "$id": "http://foo.bar/schema/person",
#   "description": "My description",
#   "$ref": "#/$defs/Person",
#   "$defs": {
#     "Address": {
#       "type": [
#         "object",
#         "null"
#       ],
#       "properties": {
#         "city": {
#           "type": [
#             "string",
#             "null"
#           ]
#         }
#       }
#     },
#     "Person": {
#       "type": "object",
#       "properties": {
#         "name": {
#           "type": [
#             "string",
#             "null"
#           ]
#         },
#         "address": {
#           "$ref": "#/$defs/Address"
#         }
#       }
#     }
#   }
# }

You can also use a command line tool to do it:

$ shaleb -i data_model.rb -r Person -p

If you want to convert your own types to JSON Schema types use:

require 'shale'
require 'shale/schema'

class MyEmailType < Shale::Type::Value
  ...
end

class MyEmailJSONType < Shale::Schema::JSONGenerator::Base
  def as_type
    { 'type' => 'string', 'format' => 'email' }
  end
end

Shale::Schema::JSONGenerator.register_json_type(MyEmailType, MyEmailJSONType)

Compiling JSON Schema into Shale model

⚠️ Only Draft 2020-12 JSON Schema is supported

To generate Shale data model from JSON Schema use Shale::Schema.from_json. You can pass root_name: 'Foobar' to change the name of the root type and namespace_mapping: {} to map schemas to Ruby modules:

require 'shale/schema'

schema = <<~SCHEMA
{
  "type": "object",
  "properties": {
    "firstName": { "type": "string" },
    "lastName": { "type": "string" },
    "address": { "$ref": "http://bar.com" }
  },
  "$defs": {
    "Address": {
      "$id": "http://bar.com",
      "type": "object",
      "properties": {
        "street": { "type": "string" },
        "city": { "type": "string" }
      }
    }
  }
}
SCHEMA

Shale::Schema.from_json(
  [schema],
  root_name: 'Person',
  namespace_mapping: {
    nil => 'Api::Foo', # default schema (without ID)
    'http://bar.com' => 'Api::Bar',
  }
)

# =>
#
# {
#   "api/bar/address" => "
#     require 'shale'
#
#     module Api
#       module Bar
#         class Address < Shale::Mapper
#           attribute :street, Shale::Type::String
#           attribute :city, Shale::Type::String
#
#           json do
#             map 'street', to: :street
#             map 'city', to: :city
#           end
#         end
#       end
#     end
#   ",
#   "api/foo/person" => "
#     require 'shale'
#
#     require_relative '../bar/address'
#
#     module Api
#       module Foo
#         class Person < Shale::Mapper
#           attribute :first_name, Shale::Type::String
#           attribute :last_name, Shale::Type::String
#           attribute :address, Api::Bar::Address
#
#           json do
#             map 'firstName', to: :first_name
#             map 'lastName', to: :last_name
#             map 'address', to: :address
#           end
#         end
#       end
#     end
#   "
# }

You can also use a command line tool to do it:

$ shaleb -c -i schema.json -r Person -m http://bar.com=Api::Bar,=Api::Foo

Generating XML Schema

To generate XML Schema from your Shale data model use:

require 'shale/schema'

Shale::Schema.to_xml(Person, pretty: true)

# =>
#
# {
#   'schema0.xsd' => '
#     <xs:schema
#       elementFormDefault="qualified"
#       attributeFormDefault="qualified"
#       xmlns:xs="http://www.w3.org/2001/XMLSchema"
#       xmlns:foo="http://foo.com"
#     >
#       <xs:import namespace="http://foo.com" schemaLocation="schema1.xsd"/>
#       <xs:element name="person" type="Person"/>
#       <xs:complexType name="Person">
#         <xs:sequence>
#           <xs:element name="name" type="xs:string" minOccurs="0"/>
#           <xs:element ref="foo:address" minOccurs="0"/>
#         </xs:sequence>
#       </xs:complexType>
#     </xs:schema>',
#
#   'schema1.xsd' => '
#     <xs:schema
#       elementFormDefault="qualified"
#       attributeFormDefault="qualified"
#       targetNamespace="http://foo.com"
#       xmlns:xs="http://www.w3.org/2001/XMLSchema"
#       xmlns:foo="http://foo.com"
#     >
#       <xs:element name="address" type="foo:Address"/>
#       <xs:complexType name="Address">
#         <xs:sequence>
#           <xs:element name="city" type="xs:string" minOccurs="0"/>
#         </xs:sequence>
#       </xs:complexType>
#     </xs:schema>'
# }

You can also use a command line tool to do it:

$ shaleb -i data_model.rb -r Person -p -f xml

If you want to convert your own types to XML Schema types use:

require 'shale'
require 'shale/schema'

class MyEmailType < Shale::Type::Value
  ...
end

Shale::Schema::XMLGenerator.register_xml_type(MyEmailType, 'myEmailXMLType')

Compiling XML Schema into Shale model

To generate Shale data model from XML Schema use Shale::Schema.from_xml. You can pass namespace_mapping: {} to map XML namespaces to Ruby modules:

require 'shale/schema'

schema1 = <<~SCHEMA
<xs:schema
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:bar="http://bar.com"
  elementFormDefault="qualified"
>
  <xs:import namespace="http://bar.com" />

  <xs:element name="Person" type="Person" />

  <xs:complexType name="Person">
    <xs:sequence>
      <xs:element name="Name" type="xs:string" />
      <xs:element ref="bar:Address" />
    </xs:sequence>
  </xs:complexType>
</xs:schema>
SCHEMA

schema2 = <<~SCHEMA
<xs:schema
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:bar="http://bar.com"
  targetNamespace="http://bar.com"
  elementFormDefault="qualified"
>
  <xs:element name="Address" type="bar:Address" />

  <xs:complexType name="Address">
    <xs:sequence>
      <xs:element name="Street" type="xs:string" />
      <xs:element name="City" type="xs:string" />
    </xs:sequence>
  </xs:complexType>
</xs:schema>
SCHEMA

Shale::Schema.from_xml(
  [schema1, schema2],
  namespace_mapping: {
    nil => 'Api::Foo', # no namespace
    'http://bar.com' => 'Api::Bar',
  }
)

# =>
#
# {
#   "api/bar/address" => "
#     require 'shale'
#
#     module Api
#       module Bar
#         class Address < Shale::Mapper
#           attribute :street, Shale::Type::String
#           attribute :city, Shale::Type::String
#
#           xml do
#             root 'Address'
#             namespace 'http://bar.com', 'bar'
#
#             map_element 'Street', to: :street
#             map_element 'City', to: :city
#           end
#         end
#       end
#     end
#   ",
#   "api/foo/person" => "
#     require 'shale'
#
#     require_relative '../bar/address'
#
#     module Api
#       module Foo
#         class Person < Shale::Mapper
#           attribute :name, Shale::Type::String
#           attribute :address, Api::Bar::Address
#
#           xml do
#             root 'Person'
#
#             map_element 'Name', to: :name
#             map_element 'Address', to: :address, prefix: 'bar', namespace: 'http://bar.com'
#           end
#         end
#       end
#     end
#   "
# }

You can also use a command line tool to do it:

$ shaleb -c -f xml -i schema.xml -m http://bar.com=Api::Bar,=Api::Foo

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/kgiszczak/shale.

License

The gem is available as open source under the terms of the MIT License.