Module: Flows::Plugin::OutputContract

Defined in:
lib/flows/plugin/output_contract.rb,
lib/flows/plugin/output_contract/dsl.rb,
lib/flows/plugin/output_contract/errors.rb,
lib/flows/plugin/output_contract/wrapper.rb

Overview

Allows to make a contract check and transformation for #call method execution in any class.

Plugin applies a wrapper to a #call instance method. This wrapper will do the following:

  • check that Result instance is returned by #call
  • check that returned Result#status is expected
  • check that returned result data conforms Contract assigned to a particular result type and status
  • applies contract transform to the returned data
  • returns Result with the same status and type, wraps transformed data inside.

Plugin provides DSL to express expected result statuses and assigned contracts. Contracts definition reuses Contract.make to execute block and get a contract.

  • success_with(status, &block) - defines contract for a successful result with status status.
  • failure_with(status, &block) - defines contract for a failure result with status status.
  • skip_output_contract - disables contract check and transformation for current class and children.

Examples:

with one possible output contract

class DoJob
  include Flows::Result::Helpers
  include Flows::Plugin::OutputContract

  success_with :ok do
    Integer
  end

  def call(a, b)
    ok_data(a + b)
  end
end

DoJob.new.call(1, 2).unwrap
# => 3

DoJob.new.call('a', 'b')
# Flows::Contract::Error exception raised

with multiple contracts

class DoJob
  include Flows::Result::Helpers
  include Flows::Plugin::OutputContract

  success_with :int_sum do
    Integer
  end

  success_with :float_sum do
    Float
  end

  failure_with :err do
    hash_of(
      key: Symbol,
      msg: String
    )
  end

  def call(a, b)
    if a.is_a?(Float) || b.is_a?(Float)
      ok_data(a + b, status: :float_sum)
    elsif a.is_a?(Integer) && b.is_a?(Integer)
      ok_data(a + b, status: :int_sum)
    else
      err(key: :unexpected_type, msg: "Unexpected argument types")
    end
  end
end

Since:

  • 0.4.0

Defined Under Namespace

Modules: DSL, Wrapper Classes: ContractError, Error, NoContractError, ResultTypeError, StatusError

Class Method Summary collapse

Class Method Details

.included(mod) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Since:

  • 0.4.0



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# File 'lib/flows/plugin/output_contract.rb', line 79

def self.included(mod)
  mod.extend(DSL)
  mod.prepend(Wrapper)
end