Rulix

Rulix is a gem for defining and using rules to manipulate, validate, and transform datasets.

Installation

Add this line to your application's Gemfile:

gem 'rulix'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rulix

Usage

Rulix is an engine for defining rulesets that you can apply to your datasets. It has two primary functions; Mutation and Validation.

Rules

Rules in Rulix are, at their core, procs. Anything that can be coerced into a proc can be used as a rule.

# Procs and lambdas work fine
-> (value) { value.gsub /\d+/, '' }

# Symbols respond to :to_proc, so they work too
:strip

# Any object that can be coerced into a proc will work!
class DashStripper
  def strip_dashes string
    string.gsub /-/, ''
  end

  def to_proc
    method(:strip_dashes)
  end
end

DashStripper.new

Using Rules

Rules can be supplied directly in a ruleset as long as they can be coerced into procs with to_proc.

ruleset = {
  first_name: -> (name) { name.reverse },
  last_name: :strip
}

For a more permanent rule definition, you can register a procable object or block under a symbol through the embedded registry for Rulix to use.

my_super_neat_transformation = -> (string) { string.upcase.chars.shuffle.join }

Rulix::Mutator.register :make_super_neat, my_super_neat_transformation

Then, you can supply the symbol in a Rulix ruleset.

dataset = {
  foo: 'oh man this is going to be so cool'
}

rules = {
  foo: :make_super_neat
}

Rulix::Mutator.run dataset, rules
#=> {:foo=>" T OI   INHOHMSNSTS B OIAOEOGGOLC "}

Configuring Rules

Some rules may need additional definition or configuration based on context. If you are writing a rule that needs additional options passed in, make the options a hash that is either taken as initialization arguments, or as the first argument of your proc.

# Configurable proc
trimmer = -> (options, value) { value[0..options[:trim_to] - 1] }

Rulix::Mutator.register :trim, trimmer

{ first_name: { trim: { trim_to: 5 } } }

# Configured procable object
class CharacterRemover
  attr_accessor :character

  def initialize options = nil
    options ||= {}

    self.character = options[:character]
  end

  def remove_from string
    string.gsub character, ''
  end

  def to_proc
    method(:remove_from)
  end
end

Rulesets

Rulix rulesets are just Ruby hashes.

ruleset = { first_name: :strip }

In order to properly map to a dataset, they need to follow the structure of the dataset that they're validating.

ruleset = { first_name: :strip }

# This will work
proper_dataset = { first_name: 'Bob ' }

# This one won't :(
bad_dataset = { person: { first_name: 'Bob ' } }

Rulix does support nested hashes in a dataset, as long as the ruleset matches the format.

dataset = {
  person: {
    first_name: 'Bob '
  }
}

ruleset = {
  person: {
    first_name: :strip
  }
}

Multiple rules can be applied to the same data point in a dataset.

dataset = { name: 'Bob   Johnson  ' }

ruleset = { name: [:squeeze_spaces, :strip] }

Rulix::Mutator.run dataset, ruleset
#=> { name: 'Bob Johnson' }

Mutation

You can mutate a dataset with Rulix::Mutator. This is most useful for sanitizing user inputs (like params hashes in Rails), but it can be used for any operation that needs to perform consistent mutations on a set of data.

dataset = {
  first_name: 'Bob ',
  last_name: 'Johnson '
}

ruleset = {
  first_name: :strip,
  last_name: :strip
}

Rulix::Mutator.run dataset, ruleset
#=> { first_name: 'Bob', last_name: 'Johnson' }

See the wiki for a list of included mutator functions.

Validation

Use Rulix::Validator to validate a dataset. Rulix::Validator.run will return a Rulix::Validation object, which is just hash with a few extra helpful methods (like valid? and error_messages).

dataset = {
  phone: {
    number: '800-555-5555'
  }
}

ruleset = {
  phone: {
    number: [format: /\d{10}/]
  }
}

result = Rulix::Validator.run dataset, ruleset

result.valid?
#=> false
result
#=> { phone: { number: ['does not match format'] } }
result.error_messages
#=> ['Number does not match format']

See the wiki for a list of included validation functions. If you have a validation function that you like that you think should be included in Rulix's base set, submit a pull request!

Validating with ActiveRecord

Rulix comes with a plugin class that you can use to validate ActiveRecord models.

class User < ActiveRecord::Base
  validates :email, uniqueness: true

  validates_with Rulix::ActiveRecordValidator, ruleset: {
    email: { format: { pattern: /.*@.*/, message: 'is not an email address' } }
  }
end

user = User.new email: 'foobar'

user.valid?
#=> false
user.errors.full_messages
#=> ['Email is not an email address']

The adapter can be used alongside ActiveRecord's own validators, so you can keep using ActiveRecord to validate the things it's good at, and delegate the rest to Rulix!

Custom Validators and Mutators

You can write your own mutators and validators and make them available to Rulix for building rulesets as long as they implement their respective interfaces.

Custom Mutators

A mutator changes data, so its only interface requirement is that it returns a modified version of the supplied argument.

string = 'A String of Sorts'
data = { foo: string }
bad_rule = -> (str) { [str] }

rules = { foo: [bad_rule, :strip] }

Rulix::Mutator.run data, rules
#=> NoMethodError: undefined method `strip' for ["A String of Sorts"]:Array

Custom Validators

Validators should return true if the rule is satisfied, and [false, error_message] if the validation fails. Rulix will run all supplied validations against the left-hand argument and compile the errors into a single array in place.

Rulix::Validator will always return an array under the given validated key, even if there is only one error.

Rulix::Validator.register :doesnt_end_in_oo do |val|
  val.end_with?('oo') ? [false, 'ends in oo'] : true
end

data = {
  my_field: 'foo'
}

rules = {
  my_field: [:number, :doesnt_end_in_oo]
}

Rulix::Validator.run data, rules
#=> { my_field: ['is not a number', 'ends in oo'] }

The error_message compontent of your validations can be anything you want; the results will be concatenated into a single array.

Rulix::Validator.register :has_a_digit do |val|
  /\d/.match(val) ? true : [false, { code: '001', message: 'The value supplied does not contain a digit!' }]
end

data = {
  my_field: 'bar'
}

rules = {
  my_field: [:has_a_digit]
}

Rulix::Validator.run data, rules
#=> { my_field: [{ code: '001', message: 'The value supplied does not contain a digit!' }] }

Contributing

Fork it ( https://github.com/blarshk/rulix/fork )
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create a new Pull Request

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