Module: Coercive

Defined in:
lib/coercive.rb

Overview

Public: The Coercive module implements a succinct DSL for declaring callable modules that will validate and coerce input data to an expected format.

Defined Under Namespace

Classes: Error

Instance Method Summary collapse

Instance Method Details

#call(input) ⇒ Object

Public: Coercive the given input using the declared attribute coercions.

input - input Hash with string keys that correspond to declared attributes.

Returns a Hash with known attributes as string keys and coerced values. Raises a Coercive::Error if the given input is not a Hash, or if there are any unknown string keys in the Hash, or if the values for the known keys do not pass the inner coercions for the associated declared attributes.



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# File 'lib/coercive.rb', line 25

def call(input)
  fail Coercive::Error.new("not_valid") unless input.is_a?(Hash)

  errors  = {}

  # Fetch attributes from the input Hash into the fetched_attrs Hash.
  #
  # Each fetch function is responsible for fetching its associated attribute
  # into the fetched_attrs Hash, or choosing not to fetch it, or choosing to
  # raise a Coercive::Error.
  #
  # These fetch functions encapsulate the respective strategies for dealing
  # with required, optional, or implicit attributes appropriately.
  fetched_attrs = {}
  attr_fetch_fns.each do |name, fetch_fn|
    begin
      fetch_fn.call(input, fetched_attrs)
    rescue Coercive::Error => e
      errors[name] = e.errors
    end
  end

  # Check for unknown names in the input (not declared, and thus not fetched).
  input.each_key do |name|
    errors[name] = "unknown" unless fetched_attrs.key?(name)
  end

  # Coercive fetched attributes into the coerced_attrs Hash.
  #
  # Each coerce function will coerce the given input value for that attribute
  # to an acceptable output value, or choose to raise a Coercive::Error.
  coerced_attrs = {}
  fetched_attrs.each do |name, value|
    coerce_fn = attr_coerce_fns.fetch(name)
    begin
      coerced_attrs[name] = coerce_fn.call(value)
    rescue Coercive::Error => e
      errors[name] = e.errors
    end
  end

  # Fail if fetching or coercion caused any errors.
  fail Coercive::Error.new(errors) unless errors.empty?

  coerced_attrs
end