activerecord_json_validator: A Ruby repository from kyrofa

ActiveRecord::JSONValidator makes it easy to validate
JSON attributes against a JSON schema.

Installation

Add this line to your application's Gemfile:

gem 'activerecord_json_validator', '~> 2.1.0'

Usage

JSON Schema

Schemas should be a JSON file

{
  "type": "object",
  "$schema": "http://json-schema.org/draft-04/schema#",
  "properties": {
    "city": { "type": "string" },
    "country": { "type": "string" }
  },
  "required": ["country"]
}

Ruby

create_table "users" do |t|
  t.string "name"
  t.json "profile" # First-class JSON with PostgreSQL, yo.
end

class User < ActiveRecord::Base
  # Constants
  PROFILE_JSON_SCHEMA = Rails.root.join('config', 'schemas', 'profile.json')

  # Validations
  validates :name, presence: true
  validates :profile, presence: true, json: { schema: PROFILE_JSON_SCHEMA }
end

user = User.new(name: 'Samuel Garneau', profile: { city: 'Quebec City' })
user.valid? # => false

user = User.new(name: 'Samuel Garneau', profile: { city: 'Quebec City', country: 'Canada' })
user.valid? # => true

user = User.new(name: 'Samuel Garneau', profile: '{invalid JSON":}')
user.valid? # => false
user.profile_invalid_json # => '{invalid JSON":}'

Options

Option	Description
`:schema`	The JSON schema to validate the data against (see Schema section)
`:value`	The actual value to use when validating (see Value section)
`:message`	The ActiveRecord message added to the record errors (see Message section)
`:options`	A `Hash` of `json_schemer`-supported options to pass to the validator

Schema

ActiveRecord::JSONValidator uses the json_schemer gem to validate the JSON data against a JSON schema.

Additionally, you can use a Symbol or a Proc. Both will be executed in the context of the validated record (Symbol will be sent as a method and the Proc will be instance_execed)

class User < ActiveRecord::Base
  # Constants
  PROFILE_REGULAR_JSON_SCHEMA = Rails.root.join('config', 'schemas', 'profile.json_schema')
  PROFILE_ADMIN_JSON_SCHEMA = Rails.root.join('config', 'schemas', 'profile_admin.json_schema')

  # Validations
  validates :profile, presence: true, json: { schema: lambda { dynamic_profile_schema } } # `schema: :dynamic_profile_schema` would also work

  def dynamic_profile_schema
    admin? ? PROFILE_ADMIN_JSON_SCHEMA : PROFILE_REGULAR_JSON_SCHEMA
  end
end

The schema is passed to the JSONSchemer.schema function, so it can be anything supported by it:

class User < ActiveRecord::Base
  # Constants
  JSON_SCHEMA = Rails.root.join('config', 'schemas', 'profile.json_schema')
  # JSON_SCHEMA = { 'type' => 'object', 'properties' => { 'foo' => { 'type' => 'integer', 'minimum' => 3 } } }
  # JSON_SCHEMA = '{"type":"object","properties":{"foo":{"type":"integer","minimum":3}}}'

  # Validations
  validates :profile, presence: true, json: { schema: JSON_SCHEMA }
end

Value

By default, the validator will use the “getter” method to the fetch attribute value and validate the schema against it.

# Will validate `self.foo`
validates :foo, json: { schema: SCHEMA }

But you can change this behavior if the getter method doesn’t return raw JSON data (a Hash):

# Will validate `self[:foo]`
validates :foo, json: { schema: SCHEMA, value: ->(record, _, _) { record[:foo] } }

You could also implement a “raw getter” if you want to avoid the value option:

# Will validate `self[:foo]`
validates :raw_foo, json: { schema: SCHEMA }

def raw_foo
  self[:foo]
end

Message

Like any other ActiveModel validation, you can specify either a Symbol or String value for the :message option. The default value is :invalid_json.

However, you can also specify a Proc that returns an array of errors. The Proc will be called with a single argument — an array of errors returned by the JSON schema validator. So, if you’d like to add each of these errors as a first-level error for the record, you can do this:

class User < ActiveRecord::Base
  # Validations
  validates :profile, presence: true, json: { message: ->(errors) { errors }, schema: 'foo.json_schema' }
end

user = User.new.tap(&:valid?)
user.errors.full_messages
# => [
#      'The property '#/email' of type Fixnum did not match the following type: string in schema 2d44293f-cd9d-5dca-8a6a-fb9db1de722b#',
#      'The property '#/full_name' of type Fixnum did not match the following type: string in schema 2d44293f-cd9d-5dca-8a6a-fb9db1de722b#',
#    ]

License

The tree logo is based on this lovely icon by Sara Quintana, from The Noun Project. Used under a Creative Commons BY 3.0 license.

About Mirego

Mirego is a team of passionate people who believe that work is a place where you can innovate and have fun. We're a team of talented people who imagine and build beautiful Web and mobile applications. We come together to share ideas and change the world.

We also love open-source software and we try to give back to the community as much as we can.

kyrofa/activerecord_json_validator