Scheemer

Scheemer uses Dry::Schema to enable us to write consistent looking structural parameter validation and data accessing on our services.

Usage

Using the Scheemer

Scheemer::DSL ties together the parameters key translation and structural validation.

klass = Class.new do
  extend Scheemer::DSL

  schema do
    required(:root).hash do
      required(:someValue).filled(:string)
    end
  end

  on_missing path: "book.author.name", fallback_to: { "Stephen King" }
end

record = klass.new({ root: { someValue: "testing" } })
record.some_value # => "testing"
record.book.dig(:author, :name) # => "Stephen King"

Optional Extra Data

When using the DSL, it's possible to inject extra parameters into your custom validations through the constructor. This can be helpful in cases where validations require access to outside data (e.g. database records, user session).

klass = Class.new do
  extend Scheemer::DSL

  schema do
    required(:root).hash do
      required(:someValue).filled(:string)
    end
  end

  def validate!(data)
    p data[:records] # => [ ... ]
    p data[:some_extra_value] # => "may be for validation"
  end
end
record = klass.new(
  { root: { someValue: "testing" } },
  { records: [1, 2], some_extra_value: "may be for validation" }
)

Using Scheemer::Params

Scheemer::Params handles the parameters key translation.

klass = Class.new do
  extend Scheemer::Params::DSL

  def initialize(...)
    super

    ...
  end
end

record = klass.new({ someValue: "testing" })
record.some_value # => "testing"

Using Scheemer::Schema

Scheemer::Schema::DSL handles the structural validation.

klass = Class.new do
  extend Scheemer::Schema::DSL

  schema do
    required(:name).filled(:string)
  end

  attr_reader :contents

  def initialize(params)
    @contents = self.class.validate_schema!(params)
  end
end

klass.new({ name: 1 }) # => Error:'{:name=>['must be a string"]}"

Development

$ docker-compose run scheemer /bin/sh
$ docker-compose run scheemer rspec
$ docker-compose build scheemer

Installation

Install the gem and add to the application's Gemfile by executing:

$ bundle add aion-dk/scheemer

If bundler is not being used to manage dependencies, install the gem by executing:

$ gem install aion-dk/scheemer

License

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