![Ruby](https://img.shields.io/badge/ruby-2.2+-ruby.svg?colorA=99004d&colorB=cc0066) [![Gem](https://img.shields.io/gem/v/u-case.svg?style=flat-square)](https://rubygems.org/gems/u-case) [![Build Status](https://travis-ci.com/serradura/u-case.svg?branch=master)](https://travis-ci.com/serradura/u-case) [![Maintainability](https://api.codeclimate.com/v1/badges/5c3c8ad1b0b943f88efd/maintainability)](https://codeclimate.com/github/serradura/u-case/maintainability) [![Test Coverage](https://api.codeclimate.com/v1/badges/5c3c8ad1b0b943f88efd/test_coverage)](https://codeclimate.com/github/serradura/u-case/test_coverage) μ-case (Micro::Case) ==================== Create simple and powerful use cases as objects. The main project goals are: 1. Easy to use and easy to learn (input **>>** process **>>** output). 2. Promote referential transparency (transforming instead of modifying) and data integrity. 3. No callbacks (e.g: before, after, around). 4. Solve complex business logic, by allowing the composition of use cases. 5. Be fast and optimized (Check out the [benchmarks](#benchmarks) section). > Note: Check out the repo https://github.com/serradura/from-fat-controllers-to-use-cases to see a Rails application that uses this gem to handle its business logic. ## Documentation Version | Documentation --------- | ------------- 3.0.0.rc3 | https://github.com/serradura/u-case/blob/master/README.md 2.6.0 | https://github.com/serradura/u-case/blob/v2.x/README.md 1.1.0 | https://github.com/serradura/u-case/blob/v1.x/README.md ## Table of Contents - [Required Ruby version](#required-ruby-version) - [Dependencies](#dependencies) - [Installation](#installation) - [Usage](#usage) - [`Micro::Case` - How to define a use case?](#microcase---how-to-define-a-use-case) - [`Micro::Case::Result` - What is a use case result?](#microcaseresult---what-is-a-use-case-result) - [What are the default result types?](#what-are-the-default-result-types) - [How to define custom result types?](#how-to-define-custom-result-types) - [Is it possible to define a custom result type without a block?](#is-it-possible-to-define-a-custom-result-type-without-a-block) - [How to use the result hooks?](#how-to-use-the-result-hooks) - [Why the hook usage without a type exposes the result itself?](#why-the-hook-usage-without-a-type-exposes-the-result-itself) - [Using decomposition to access the result data and type](#using-decomposition-to-access-the-result-data-and-type) - [What happens if a result hook was declared multiple times?](#what-happens-if-a-result-hook-was-declared-multiple-times) - [How to use the `Micro::Case::Result#then` method?](#how-to-use-the-microcaseresultthen-method) - [What does happens when a `Micro::Case::Result#then` receives a block?](#what-does-happens-when-a-microcaseresultthen-receives-a-block) - [How to make attributes data injection using this feature?](#how-to-make-attributes-data-injection-using-this-feature) - [`Micro::Cases::Flow` - How to compose use cases?](#microcasesflow---how-to-compose-use-cases) - [Is it possible to compose a use case flow with other ones?](#is-it-possible-to-compose-a-use-case-flow-with-other-ones) - [Is it possible a flow accumulates its input and merges each success result to use as the argument of the next use cases?](#is-it-possible-a-flow-accumulates-its-input-and-merges-each-success-result-to-use-as-the-argument-of-the-next-use-cases) - [How to understand what is happening during a flow execution?](#how-to-understand-what-is-happening-during-a-flow-execution) - [`Micro::Case::Result#transitions` schema](#microcaseresulttransitions-schema) - [Is it possible disable the `Micro::Case::Result#transitions`?](#is-it-possible-disable-the-microcaseresulttransitions) - [Is it possible to declare a flow which includes the use case itself?](#is-it-possible-to-declare-a-flow-which-includes-the-use-case-itself) - [`Micro::Case::Strict` - What is a strict use case?](#microcasestrict---what-is-a-strict-use-case) - [`Micro::Case::Safe` - Is there some feature to auto handle exceptions inside of a use case or flow?](#microcasesafe---is-there-some-feature-to-auto-handle-exceptions-inside-of-a-use-case-or-flow) - [`Micro::Cases::Safe::Flow`](#microcasessafeflow) - [`Micro::Case::Result#on_exception`](#microcaseresulton_exception) - [`u-case/with_activemodel_validation` - How to validate use case attributes?](#u-casewith_activemodel_validation---how-to-validate-use-case-attributes) - [If I enabled the auto validation, is it possible to disable it only in specific use case classes?](#if-i-enabled-the-auto-validation-is-it-possible-to-disable-it-only-in-specific-use-case-classes) - [`Kind::Validator`](#kindvalidator) - [`Micro::Case.config`](#microcaseconfig) - [Benchmarks](#benchmarks) - [`Micro::Case` (v2.6.0)](#microcase-v260) - [Best overall](#best-overall) - [Success results](#success-results) - [Failure results](#failure-results) - [`Micro::Case::Flow` (v2.6.0)](#microcaseflow-v260) - [Comparisons](#comparisons) - [Examples](#examples) - [1️⃣ Rails App (API)](#1️⃣-rails-app-api) - [2️⃣ CLI calculator](#2️⃣-cli-calculator) - [3️⃣ Users creation](#3️⃣-users-creation) - [4️⃣ Rescuing exception inside of the use cases](#4️⃣-rescuing-exception-inside-of-the-use-cases) - [Development](#development) - [Contributing](#contributing) - [License](#license) - [Code of Conduct](#code-of-conduct) ## Required Ruby version > \>= 2.2.0 ## Dependencies 1. [`kind`](https://github.com/serradura/kind) gem. A simple type system (at runtime) for Ruby. Used to validate method inputs using its [`activemodel validation`](https://github.com/serradura/kind#kindvalidator-activemodelvalidations) module is auto required by [`u-case/with_activemodel_validation`](#u-casewith_activemodel_validation---how-to-validate-use-case-attributes) mode, and expose `Kind::Of::Micro::Case`, `Kind::Of::Micro::Case::Result` type checkers. 2. [`u-attributes`](https://github.com/serradura/u-attributes) gem. This gem allows defining read-only attributes, that is, your objects will have only getters to access their attributes data. It is used to define the use case attributes. ## Installation Add this line to your application's Gemfile: ```ruby gem 'u-case' ``` And then execute: $ bundle Or install it yourself as: $ gem install u-case ## Usage ### `Micro::Case` - How to define a use case? ```ruby class Multiply < Micro::Case # 1. Define its input as attributes attributes :a, :b # 2. Define the method `call!` with its business logic def call! # 3. Wrap the use case result/output using the `Success(result: *)` or `Failure(result: *)` methods if a.is_a?(Numeric) && b.is_a?(Numeric) Success result: { number: a * b } else Failure result: { message: '`a` and `b` attributes must be numeric' } end end end #==========================# # Calling a use case class # #==========================# # Success result result = Multiply.call(a: 2, b: 2) result.success? # true result.data # { number: 4 } # Failure result bad_result = Multiply.call(a: 2, b: '2') bad_result.failure? # true bad_result.data # { message: "`a` and `b` attributes must be numeric" } # Note: # ---- # The result of a Micro::Case.call # is an instance of Micro::Case::Result ``` [⬆️ Back to Top](#table-of-contents-) ### `Micro::Case::Result` - What is a use case result? A `Micro::Case::Result` stores the use cases output data. These are their main methods: - `#success?` returns true if is a successful result. - `#failure?` returns true if is an unsuccessful result. - `#use_case` returns the use case responsible for it. This feature is handy to handle a flow failure (this topic will be covered ahead). - `#type` a Symbol which gives meaning for the result, this is useful to declare different types of failures or success. - `#data` the result data itself. - `#[]` and `#values_at` are shortcuts to access the `#data` values. - `#on_success` or `#on_failure` are hook methods that help you to define the application flow. - `#then` this method will allow applying a new use case if the current result was a success. The idea of this feature is to allow the creation of dynamic flows. - `#transitions` returns an array with all of transformations wich a result [has during a flow](#how-to-understand-what-is-happening-during-a-flow-execution). > **Note:** for backward compatibility, you could use the `#value` method as an alias of `#data` method. [⬆️ Back to Top](#table-of-contents-) #### What are the default result types? Every result has a type and these are the defaults: - `:ok` when success - `:error`/`:exception` when failures ```ruby class Divide < Micro::Case attributes :a, :b def call! if invalid_attributes.empty? Success result: { number: a / b } else Failure result: { invalid_attributes: invalid_attributes } end rescue => exception Failure result: exception end private def invalid_attributes attributes.select { |_key, value| !value.is_a?(Numeric) } end end # Success result result = Divide.call(a: 2, b: 2) result.type # :ok result.data # { number: 1 } result.success? # true result.use_case # #2, "b"=>2}, @a=2, @b=2, @__result=...> # Failure result (type == :error) bad_result = Divide.call(a: 2, b: '2') bad_result.type # :error bad_result.data # { invalid_attributes: { "b"=>"2" } } bad_result.failure? # true bad_result.use_case # #2, "b"=>"2"}, @a=2, @b="2", @__result=...> # Failure result (type == :exception) err_result = Divide.call(a: 2, b: 0) err_result.type # :exception err_result.data # { exception: } err_result.failure? # true err_result.use_case # #2, "b"=>0}, @a=2, @b=0, @__result=#, @type=:exception, @value=#, @success=false> # Note: # ---- # Any Exception instance which is wrapped by # the Failure(result: *) method will receive `:exception` instead of the `:error` type. ``` [⬆️ Back to Top](#table-of-contents-) #### How to define custom result types? Answer: Use a symbol as the argument of `Success()`, `Failure()` methods and declare the `result:` keyword to set the result data. ```ruby class Multiply < Micro::Case attributes :a, :b def call! if a.is_a?(Numeric) && b.is_a?(Numeric) Success result: { number: a * b } else Failure :invalid_data, result: { attributes: attributes.reject { |_, input| input.is_a?(Numeric) } } end end end # Success result result = Multiply.call(a: 3, b: 2) result.type # :ok result.data # { number: 6 } result.success? # true # Failure result bad_result = Multiply.call(a: 3, b: '2') bad_result.type # :invalid_data bad_result.data # { attributes: {"b"=>"2"} } bad_result.failure? # true ``` [⬆️ Back to Top](#table-of-contents-) #### Is it possible to define a custom result type without a block? Answer: Yes, it is possible. But this will have special behavior because the result data will be a hash with the given type as the key and true as its value. ```ruby class Multiply < Micro::Case attributes :a, :b def call! if a.is_a?(Numeric) && b.is_a?(Numeric) Success result: { number: a * b } else Failure(:invalid_data) end end end result = Multiply.call(a: 2, b: '2') result.failure? # true result.data # { :invalid_data => true } result.type # :invalid_data result.use_case.attributes # {"a"=>2, "b"=>"2"} # Note: # ---- # This feature is handy to handle failures in a flow # (this topic will be covered ahead). ``` [⬆️ Back to Top](#table-of-contents-) #### How to use the result hooks? As mentioned earlier, the `Micro::Case::Result` has two methods to improve the flow control. They are: `#on_success`, `on_failure`. The examples below show how to use them: ```ruby class Double < Micro::Case attribute :number def call! return Failure :invalid, result: { msg: 'number must be a numeric value' } unless number.is_a?(Numeric) return Failure :lte_zero, result: { msg: 'number must be greater than 0' } if number <= 0 Success result: { number: number * 2 } end end #================================# # Printing the output if success # #================================# Double .call(number: 3) .on_success { |result| p result[:number] } .on_failure(:invalid) { |result| raise TypeError, result[:msg] } .on_failure(:lte_zero) { |result| raise ArgumentError, result[:msg] } # The output because it is a success: # 6 #=============================# # Raising an error if failure # #=============================# Double .call(number: -1) .on_success { |result| p result[:number] } .on_failure { |_result, use_case| puts "#{use_case.class.name} was the use case responsible for the failure" } .on_failure(:invalid) { |result| raise TypeError, result[:msg] } .on_failure(:lte_zero) { |result| raise ArgumentError, result[:msg] } # The outputs will be: # # 1. Prints the message: Double was the use case responsible for the failure # 2. Raises the exception: ArgumentError (the number must be greater than 0) # Note: # ---- # The use case responsible for the failure will be accessible as the second hook argument ``` #### Why the hook usage without a type exposes the result itself? Answer: To allow you to define how to handle the program flow using some conditional statement (like an `if`, `case/when`). ```ruby class Double < Micro::Case attribute :number def call! return Failure(:invalid) unless number.is_a?(Numeric) return Failure :lte_zero, result: attributes(:number) if number <= 0 Success result: { number: number * 2 } end end Double .call(number: -1) .on_failure do |result, use_case| case result.type when :invalid then raise TypeError, "number must be a numeric value" when :lte_zero then raise ArgumentError, "number `#{result[:number]}` must be greater than 0" else raise NotImplementedError end end # The output will be the exception: # # ArgumentError (number `-1` must be greater than 0) ``` > **Note:** The same that was did in the previous examples could be done with `#on_success` hook! ##### Using decomposition to access the result data and type The syntax to decompose an Array can be used in methods, blocks and assigments. If you doesn't know it, check out the [Ruby doc](https://ruby-doc.org/core-2.2.0/doc/syntax/assignment_rdoc.html#label-Array+Decomposition). ```ruby # The object exposed in the hook is a Micro::Case::Result, and it can be decomposed using this syntax. e.g: Double .call(number: -2) .on_failure do |(data, type), use_case| case type when :invalid then raise TypeError, 'number must be a numeric value' when :lte_zero then raise ArgumentError, "number `#{data[:number]}` must be greater than 0" else raise NotImplementedError end end # The output will be the exception: # # ArgumentError (the number `-2` must be greater than 0) ``` > **Note:** The same that was did in the previous examples could be done with `#on_success` hook! [⬆️ Back to Top](#table-of-contents-) #### What happens if a result hook was declared multiple times? Answer: The hook always will be triggered if it matches the result type. ```ruby class Double < Micro::Case attributes :number def call! if number.is_a?(Numeric) Success :computed, result: { number: number * 2 } else Failure :invalid, result: { msg: 'number must be a numeric value' } end end end result = Double.call(number: 3) result.data # { number: 6 } result[:number] * 4 # 24 accum = 0 result .on_success { |result| accum += result[:number] } .on_success { |result| accum += result[:number] } .on_success(:computed) { |result| accum += result[:number] } .on_success(:computed) { |result| accum += result[:number] } accum # 24 result[:number] * 4 == accum # true ``` #### How to use the `Micro::Case::Result#then` method? This method allows you to create dynamic flows, so, with it, you can add new use cases or flows to continue the result transformation. e.g: ```ruby class ForbidNegativeNumber < Micro::Case attribute :number def call! return Success result: attributes if number >= 0 Failure result: attributes end end class Add3 < Micro::Case attribute :number def call! Success result: { number: number + 3 } end end result1 = ForbidNegativeNumber .call(number: -1) .then(Add3) result1.data # {'number' => -1} result1.failure? # true # --- result2 = ForbidNegativeNumber .call(number: 1) .then(Add3) result2.data # {'number' => 4} result2.success? # true ``` > **Note:** this method changes the [`Micro::Case::Result#transitions`](#how-to-understand-what-is-happening-during-a-flow-execution). [⬆️ Back to Top](#table-of-contents-) ##### What does happens when a `Micro::Case::Result#then` receives a block? It will yields self (a `Micro::Case::Result instance`) to the block and return the result of the block. e.g: ```ruby class Add < Micro::Case attributes :a, :b def call! if Kind.of?(Numeric, a, b) Success result: { sum: a + b } else Failure(:attributes_arent_numbers) end end end # -- success_result = Add .call(a: 2, b: 2) .then { |result| result.success? ? result[:sum] : 0 } puts success_result # 4 # -- failure_result = Add .call(a: 2, b: '2') .then { |result| result.success? ? result[:sum] : 0 } puts failure_result # 0 ``` [⬆️ Back to Top](#table-of-contents-) ##### How to make attributes data injection using this feature? Pass a Hash as the second argument of the `Micro::Case::Result#then` method. ```ruby Todo::FindAllForUser .call(user: current_user, params: params) .then(Paginate) .then(Serialize::PaginatedRelationAsJson, serializer: Todo::Serializer) .on_success { |result| render_json(200, data: result[:todos]) } ``` [⬆️ Back to Top](#table-of-contents-) ### `Micro::Cases::Flow` - How to compose use cases? In this case, this will be a **flow** (`Micro::Cases::Flow`). The main idea of this feature is to use/reuse use cases as steps of a new use case. ```ruby module Steps class ConvertTextToNumbers < Micro::Case attribute :numbers def call! if numbers.all? { |value| String(value) =~ /\d+/ } Success result: { numbers: numbers.map(&:to_i) } else Failure result: { message: 'numbers must contain only numeric types' } end end end class Add2 < Micro::Case::Strict attribute :numbers def call! Success result: { numbers: numbers.map { |number| number + 2 } } end end class Double < Micro::Case::Strict attribute :numbers def call! Success result: { numbers: numbers.map { |number| number * 2 } } end end class Square < Micro::Case::Strict attribute :numbers def call! Success result: { numbers: numbers.map { |number| number * number } } end end end #-------------------------------------------# # Creating a flow using Micro::Cases.flow() # #-------------------------------------------# Add2ToAllNumbers = Micro::Cases.flow([ Steps::ConvertTextToNumbers, Steps::Add2 ]) result = Add2ToAllNumbers.call(numbers: %w[1 1 2 2 3 4]) result.success? # true result.data # {:numbers => [3, 3, 4, 4, 5, 6]} #---------------------------------------------------# # An alternative way to create a flow using classes # #---------------------------------------------------# class DoubleAllNumbers < Micro::Case flow Steps::ConvertTextToNumbers, Steps::Double end DoubleAllNumbers. call(numbers: %w[1 1 b 2 3 4]). on_failure { |result| puts result[:message] } # "numbers must contain only numeric types" # Note: # ---- # When happening a failure, the use case responsible # will be accessible in the result result = DoubleAllNumbers.call(numbers: %w[1 1 b 2 3 4]) result.failure? # true result.use_case.is_a?(Steps::ConvertTextToNumbers) # true result.on_failure do |_message, use_case| puts "#{use_case.class.name} was the use case responsible for the failure" # Steps::ConvertTextToNumbers was the use case responsible for the failure end ``` [⬆️ Back to Top](#table-of-contents-) #### Is it possible to compose a use case flow with other ones? Answer: Yes, it is possible. ```ruby module Steps class ConvertTextToNumbers < Micro::Case attribute :numbers def call! if numbers.all? { |value| String(value) =~ /\d+/ } Success result: { numbers: numbers.map(&:to_i) } else Failure result: { message: 'numbers must contain only numeric types' } end end end class Add2 < Micro::Case::Strict attribute :numbers def call! Success result: { numbers: numbers.map { |number| number + 2 } } end end class Double < Micro::Case::Strict attribute :numbers def call! Success result: { numbers: numbers.map { |number| number * 2 } } end end class Square < Micro::Case::Strict attribute :numbers def call! Success result: { numbers: numbers.map { |number| number * number } } end end end DoubleAllNumbers = Micro::Cases.flow([Steps::ConvertTextToNumbers, Steps::Double]) SquareAllNumbers = Micro::Cases.flow([Steps::ConvertTextToNumbers, Steps::Square]) DoubleAllNumbersAndAdd2 = Micro::Cases.flow([DoubleAllNumbers, Steps::Add2]) SquareAllNumbersAndAdd2 = Micro::Cases.flow([SquareAllNumbers, Steps::Add2]) SquareAllNumbersAndDouble = Micro::Cases.flow([SquareAllNumbersAndAdd2, DoubleAllNumbers]) DoubleAllNumbersAndSquareAndAdd2 = Micro::Cases.flow([DoubleAllNumbers, SquareAllNumbersAndAdd2]) SquareAllNumbersAndDouble .call(numbers: %w[1 1 2 2 3 4]) .on_success { |result| p result[:numbers] } # [6, 6, 12, 12, 22, 36] DoubleAllNumbersAndSquareAndAdd2 .call(numbers: %w[1 1 2 2 3 4]) .on_success { |result| p result[:numbers] } # [6, 6, 18, 18, 38, 66] ``` Note: You can blend any of the [available syntaxes/approaches](#how-to-create-a-flow-which-has-reusable-steps-to-define-a-complex-use-case) to create use case flows - [examples](https://github.com/serradura/u-case/blob/714c6b658fc6aa02617e6833ddee09eddc760f2a/test/micro/cases/flow/blend_test.rb#L5-L35). [⬆️ Back to Top](#table-of-contents-) #### Is it possible a flow accumulates its input and merges each success result to use as the argument of the next use cases? Answer: Yes, it is possible! Look at the example below to understand how the data accumulation works inside of the flow execution. ```ruby module Users class FindByEmail < Micro::Case attribute :email def call! user = User.find_by(email: email) return Success result: { user: user } if user Failure(:user_not_found) end end end module Users class ValidatePassword < Micro::Case::Strict attributes :user, :password def call! return Failure(:user_must_be_persisted) if user.new_record? return Failure(:wrong_password) if user.wrong_password?(password) return Success result: attributes(:user) end end end module Users Authenticate = Micro::Cases.flow([ FindByEmail, ValidatePassword ]) end Users::Authenticate .call(email: 'somebody@test.com', password: 'password') .on_success { |result| sign_in(result[:user]) } .on_failure(:wrong_password) { render status: 401 } .on_failure(:user_not_found) { render status: 404 } ``` First, lets see the attributes used by each use case: ```ruby class Users::FindByEmail < Micro::Case attribute :email end class Users::ValidatePassword < Micro::Case attributes :user, :password end ``` As you can see the `Users::ValidatePassword` expects a user as its input. So, how does it receives the user? It receives the user from the `Users::FindByEmail` success result! And this, is the power of use cases composition because the output of one step will compose the input of the next use case in the flow! > input **>>** process **>>** output > **Note:** Check out these test examples [Micro::Cases::Flow](https://github.com/serradura/u-case/blob/c96a3650469da40dc9f83ff678204055b7015d01/test/micro/cases/flow/result_transitions_test.rb) and [Micro::Cases::Safe::Flow](https://github.com/serradura/u-case/blob/c96a3650469da40dc9f83ff678204055b7015d01/test/micro/cases/safe/flow/result_transitions_test.rb) to see different use cases sharing their own data. [⬆️ Back to Top](#table-of-contents-) #### How to understand what is happening during a flow execution? Use `Micro::Case::Result#transitions`! Let's use the [previous section example](#is-it-possible-a-flow-accumulates-its-input-and-merges-each-success-result-to-use-as-the-argument-of-the-next-use-cases) to ilustrate how to use this feature. ```ruby user_authenticated = Users::Authenticate.call(email: 'rodrigo@test.com', password: user_password) user_authenticated.transitions [ { :use_case => { :class => Users::FindByEmail, :attributes => { :email => "rodrigo@test.com" } }, :success => { :type => :ok, :result => { :user => # } }, :accessible_attributes => [ :email, :password ] }, { :use_case => { :class => Users::ValidatePassword, :attributes => { :user => # :password => "123456" } }, :success => { :type => :ok, :result => { :user => # } }, :accessible_attributes => [ :email, :password, :user ] } ] ``` The example above shows the output generated by the `Micro::Case::Result#transitions`. With it is possible to analyze the use cases execution order and what were the given `inputs` (`[:attributes]`) and `outputs` (`[:success][:result]`) in the entire execution. And look up the `accessible_attributes` property, it shows whats attributes are accessible in that flow step. For example, in the last step, you can see that the `accessible_attributes` increased because of the [data flow accumulation](#is-it-possible-a-flow-accumulates-its-input-and-merges-each-success-result-to-use-as-the-argument-of-the-next-use-cases). > **Note:** The [`Micro::Case::Result#then`](#how-to-use-the-microcaseresultthen-method) increments the `Micro::Case::Result#transitions`. ##### `Micro::Case::Result#transitions` schema ```ruby [ { use_case: { class: ,# Use case which was executed attributes: # (Input) The use case's attributes }, [success:, failure:] => { # (Output) type: , # Result type. Defaults: # Success = :ok, Failure = :error/:exception result: # The data returned by the use case }, accessible_attributes: , # Properties that can be accessed by the use case's attributes, # starting with Hash used to invoke it and which are incremented # with each result value of the flow's use cases. } ] ``` ##### Is it possible disable the `Micro::Case::Result#transitions`? Answer: Yes, it is! You can use the `Micro::Case.config` to do this. [Link to](#microcaseconfig) this section. #### Is it possible to declare a flow which includes the use case itself? Answer: Yes, it is! You can use the `self.call!` macro. e.g: ```ruby class ConvertTextToNumber < Micro::Case attribute :text def call! Success result: { number: text.to_i } end end class ConvertNumberToText < Micro::Case attribute :number def call! Success result: { text: number.to_s } end end class Double < Micro::Case flow ConvertTextToNumber, self.call!, ConvertNumberToText attribute :number def call! Success result: { number: number * 2 } end end result = Double.call(text: '4') result.success? # true result[:number] # "8" # NOTE: This feature can be used with the Micro::Case::Safe. # Checkout this test: https://github.com/serradura/u-case/blob/714c6b658fc6aa02617e6833ddee09eddc760f2a/test/micro/case/safe/with_inner_flow_test.rb ``` [⬆️ Back to Top](#table-of-contents-) ### `Micro::Case::Strict` - What is a strict use case? Answer: Is a use case which will require all the keywords (attributes) on its initialization. ```ruby class Double < Micro::Case::Strict attribute :numbers def call! Success result: { numbers: numbers.map { |number| number * 2 } } end end Double.call({}) # The output will be the following exception: # ArgumentError (missing keyword: :numbers) ``` [⬆️ Back to Top](#table-of-contents-) ### `Micro::Case::Safe` - Is there some feature to auto handle exceptions inside of a use case or flow? Answer: Yes, there is one! **Use cases:** Like `Micro::Case::Strict` the `Micro::Case::Safe` is another kind of use case. It has the ability to auto intercept any exception as a failure result. e.g: ```ruby require 'logger' AppLogger = Logger.new(STDOUT) class Divide < Micro::Case::Safe attributes :a, :b def call! if a.is_a?(Integer) && b.is_a?(Integer) Success result: { number: a / b} else Failure(:not_an_integer) end end end result = Divide.call(a: 2, b: 0) result.type == :exception # true result.data # { exception: # } result[:exception].is_a?(ZeroDivisionError) # true result.on_failure(:exception) do |result| AppLogger.error(result[:exception].message) # E, [2019-08-21T00:05:44.195506 #9532] ERROR -- : divided by 0 end # Note: # ---- # If you need to handle a specific error, # I recommend the usage of a case statement. e,g: result.on_failure(:exception) do |data, use_case| case exception = data[:exception] when ZeroDivisionError then AppLogger.error(exception.message) else AppLogger.debug("#{use_case.class.name} was the use case responsible for the exception") end end # Another note: # ------------ # It is possible to rescue an exception even when is a safe use case. # Examples: https://github.com/serradura/u-case/blob/714c6b658fc6aa02617e6833ddee09eddc760f2a/test/micro/case/safe_test.rb#L90-L118 ``` [⬆️ Back to Top](#table-of-contents-) #### `Micro::Cases::Safe::Flow` As the safe use cases, safe flows can intercept an exception in any of its steps. These are the ways to define one: ```ruby module Users Create = Micro::Cases.safe_flow([ ProcessParams, ValidateParams, Persist, SendToCRM ]) end # or within classes module Users class Create < Micro::Case::Safe flow ProcessParams, ValidateParams, Persist, SendToCRM end end ``` [⬆️ Back to Top](#table-of-contents-) #### `Micro::Case::Result#on_exception` In functional programming errors/exceptions are handled as regular data, the idea is to transform the output even when it happens an unexpected behavior. For many, [exceptions are very similar to the GOTO statement](https://softwareengineering.stackexchange.com/questions/189222/are-exceptions-as-control-flow-considered-a-serious-antipattern-if-so-why), jumping the application flow to paths which could be difficult to figure out how things work in a system. To address this the `Micro::Case::Result` has a special hook `#on_exception` to helping you to handle the control flow in the case of exceptions. > **Note**: this feature will work better if you use it with a `Micro::Case::Safe` use case/flow. How does it work? ```ruby class Divide < Micro::Case::Safe attributes :a, :b def call! Success result: { division: a / b } end end Divide .call(a: 2, b: 0) .on_success { |result| puts result[:division] } .on_exception(TypeError) { puts 'Please, use only numeric attributes.' } .on_exception(ZeroDivisionError) { |_error| puts "Can't divide a number by 0." } .on_exception { |_error, _use_case| puts 'Oh no, something went wrong!' } # Output: # ------- # Can't divide a number by 0 # Oh no, something went wrong! Divide. .call(a: 2, b: '2'). .on_success { |result| puts result[:division] } .on_exception(TypeError) { puts 'Please, use only numeric attributes.' } .on_exception(ZeroDivisionError) { |_error| puts "Can't divide a number by 0." } .on_exception { |_error, _use_case| puts 'Oh no, something went wrong!' } # Output: # ------- # Please, use only numeric attributes. # Oh no, something went wrong! ``` As you can see, this hook has the same behavior of `result.on_failure(:exception)`, but, the ideia here is to have a better communication in the code, making an explicit reference when some failure happened because of an exception. [⬆️ Back to Top](#table-of-contents-) ### `u-case/with_activemodel_validation` - How to validate use case attributes? **Requirement:** To do this your application must have the [activemodel >= 3.2, < 6.1.0](https://rubygems.org/gems/activemodel) as a dependency. ```ruby # # By default, if your application has the activemodel as a dependency, # any kind of use case can use it to validate their attributes. # class Multiply < Micro::Case attributes :a, :b validates :a, :b, presence: true, numericality: true def call! return Failure :validation_error, result: { errors: self.errors } if invalid? Success result: { number: a * b } end end ``` But if do you want an automatic way to fail your use cases on validation errors, you can: 1. **require 'u-case/with_activemodel_validation'** mode ```ruby gem 'u-case', require: 'u-case/with_activemodel_validation' ``` 2. Use the `Micro::Case.config` to enable it. [Link to](#microcaseconfig) this section. Using this approach, you can rewrite the previous example with less code. e.g: ```ruby require 'u-case/with_activemodel_validation' class Multiply < Micro::Case attributes :a, :b validates :a, :b, presence: true, numericality: true def call! Success result: { number: a * b } end end # Note: # ---- # After requiring the validation mode, the # Micro::Case::Strict and Micro::Case::Safe classes will inherit this new behavior. ``` #### If I enabled the auto validation, is it possible to disable it only in specific use case classes? Answer: Yes, it is possible. To do this, you only need to use the `disable_auto_validation` macro. e.g: ```ruby require 'u-case/with_activemodel_validation' class Multiply < Micro::Case disable_auto_validation attribute :a attribute :b validates :a, :b, presence: true, numericality: true def call! Success result: { number: a * b } end end Multiply.call(a: 2, b: 'a') # The output will be the following exception: # TypeError (String can't be coerced into Integer) ``` [⬆️ Back to Top](#table-of-contents-) #### `Kind::Validator` The [kind gem](https://github.com/serradura/kind) has a module to enable the validation of data type through [`ActiveModel validations`](https://guides.rubyonrails.org/active_model_basics.html#validations). So, when you require the `'u-case/with_activemodel_validation'`, this module will require the [`Kind::Validator`](https://github.com/serradura/kind#kindvalidator-activemodelvalidations). The example below shows how to validate the attributes data types. ```ruby class Todo::List::AddItem < Micro::Case attributes :user, :params validates :user, kind: User validates :params, kind: ActionController::Parameters def call! todo_params = params.require(:todo).permit(:title, :due_at) todo = user.todos.create(todo_params) Success result: { todo: todo } rescue ActionController::ParameterMissing => e Failure :parameter_missing, result: { message: e.message } end end ``` [⬆️ Back to Top](#table-of-contents-) ## `Micro::Case.config` The idea of this feature is to allow the configuration of some `u-case` features/modules. I recommend you use it only once in your codebase. e.g. In a Rails initializer. You can see below, which are all of the available configurations with their default values: ```ruby Micro::Case.config do |config| # Use ActiveModel to auto-validate your use cases' attributes. config.enable_activemodel_validations = false # Use to enable/disable the `Micro::Case::Results#transitions` tracking. config.enable_transitions = true end ``` [⬆️ Back to Top](#table-of-contents-) ## Benchmarks ### `Micro::Case` (v2.6.0) #### Best overall The table below contains the average between the [Success results](#success-results) and [Failure results](#failure-results) benchmarks. | Gem / Abstraction | Iterations per second | Comparison | | ---------------------- | --------------------: | ----------------: | | **Micro::Case** | 105124.3 | _**The Fastest**_ | | Dry::Monads | 103290.1 | 0.02x slower | | Interactor | 21342.3 | 4.93x slower | | Trailblazer::Operation | 14652.7 | 7.17x slower | | Dry::Transaction | 5310.3 | 19.80x slower | --- #### Success results | Gem / Abstraction | Iterations per second | Comparison | | ----------------- | --------------------: | ----------------: | | Dry::Monads | 134801.0 | _**The Fastest**_ | | **Micro::Case** | 105909.2 | 1.27x slower | | Interactor | 29458.2 | 4.58x slower | | Trailblazer::Operation | 14714.9 | 9.16x slower | | Dry::Transaction | 5642.6 | 28.89x slower |
Show the full benchmark/ips results. ```ruby # Warming up -------------------------------------- # Interactor 2.897k i/100ms # Trailblazer::Operation 1.494k i/100ms # Dry::Monads 13.854k i/100ms # Dry::Transaction 561.000 i/100ms # Micro::Case 10.523k i/100ms # Micro::Case::Strict 7.982k i/100ms # Micro::Case::Safe 10.568k i/100ms # Calculating ------------------------------------- # Interactor 29.458k (± 3.4%) i/s - 147.747k in 5.021405s # Trailblazer::Operation 14.715k (± 1.8%) i/s - 74.700k in 5.078128s # Dry::Monads 134.801k (± 8.7%) i/s - 678.846k in 5.088739s # Dry::Transaction 5.643k (± 2.1%) i/s - 28.611k in 5.072969s # Micro::Case 105.909k (± 2.4%) i/s - 536.673k in 5.070329s # Micro::Case::Strict 84.234k (± 1.5%) i/s - 423.046k in 5.023447s # Micro::Case::Safe 105.725k (± 1.9%) i/s - 538.968k in 5.099817s # Comparison: # Dry::Monads: 134801.0 i/s # Micro::Case: 105909.2 i/s - 1.27x (± 0.00) slower # Micro::Case::Safe: 105725.0 i/s - 1.28x (± 0.00) slower # Micro::Case::Strict: 84234.4 i/s - 1.60x (± 0.00) slower # Interactor: 29458.2 i/s - 4.58x (± 0.00) slower # Trailblazer::Operation: 14714.9 i/s - 9.16x (± 0.00) slower # Dry::Transaction: 5642.6 i/s - 23.89x (± 0.00) slower ```
https://github.com/serradura/u-case/blob/master/benchmarks/use_case/with_success_result.rb #### Failure results | Gem / Abstraction | Iterations per second | Comparison | | ----------------- | --------------------: | ----------------: | | **Micro::Case** | 104339.4 | _**The Fastest**_ | | Dry::Monads | 71779.2 | 1.45x slower | | Trailblazer::Operation | 14590.6 | 7.15x slower | | Interactor | 13226.5 | 7.89x slower | | Dry::Transaction | 4978.1 | 20.96x slower |
Show the full benchmark/ips results. ```ruby # Warming up -------------------------------------- # Interactor 1.339k i/100ms # Trailblazer::Operation 1.393k i/100ms # Dry::Monads 7.208k i/100ms # Dry::Transaction 423.000 i/100ms # Micro::Case 9.620k i/100ms # Micro::Case::Strict 8.238k i/100ms # Micro::Case::Safe 9.906k i/100ms # Calculating ------------------------------------- # Interactor 13.227k (± 3.3%) i/s - 66.950k in 5.067145s # Trailblazer::Operation 14.591k (± 4.0%) i/s - 73.829k in 5.069162s # Dry::Monads 71.779k (± 2.5%) i/s - 360.400k in 5.024294s # Dry::Transaction 4.978k (± 3.3%) i/s - 24.957k in 5.019153s # Micro::Case 103.957k (± 1.8%) i/s - 529.100k in 5.091221s # Micro::Case::Strict 83.094k (± 2.0%) i/s - 420.138k in 5.058233s # Micro::Case::Safe 104.339k (± 1.7%) i/s - 525.018k in 5.033381s # Comparison: # Micro::Case::Safe: 104339.4 i/s # Micro::Case: 103957.2 i/s - same-ish: difference falls within error # Micro::Case::Strict: 83094.5 i/s - 1.26x (± 0.00) slower # Dry::Monads: 71779.2 i/s - 1.45x (± 0.00) slower # Trailblazer::Operation: 14590.6 i/s - 7.15x (± 0.00) slower # Interactor: 13226.5 i/s - 7.89x (± 0.00) slower # Dry::Transaction: 4978.1 i/s - 20.96x (± 0.00) slower ```
https://github.com/serradura/u-case/blob/master/benchmarks/use_case/with_failure_result.rb --- ### `Micro::Case::Flow` (v2.6.0) | Gems / Abstraction | [Success results](https://github.com/serradura/u-case/blob/master/benchmarks/flow/with_success_result.rb#L40) | [Failure results](https://github.com/serradura/u-case/blob/master/benchmarks/flow/with_failure_result.rb#L40) | | ------------------ | ----------------: | ----------------: | | Micro::Case::Flow | _**The Fastest**_ | _**The Fastest**_ | | Micro::Case::Safe::Flow | 0x slower | 0x slower | | Interactor::Organizer | 1.27x slower | 5.48x slower | \* The `Dry::Monads`, `Dry::Transaction`, `Trailblazer::Operation` are out of this analysis because all of them doesn't have this kind of feature.
Success results - Show the full benchmark/ips results. ```ruby # Warming up -------------------------------------- # Interactor::Organizer 4.765k i/100ms # Micro::Case::Flow 5.372k i/100ms # Micro::Case::Safe::Flow 5.855k i/100ms # Calculating ------------------------------------- # Interactor::Organizer 48.598k (± 5.2%) i/s - 243.015k in 5.014307s # Micro::Case::Flow 61.606k (± 4.4%) i/s - 311.576k in 5.068602s # Micro::Case::Safe::Flow 60.688k (± 4.8%) i/s - 304.460k in 5.028877s # Comparison: # Micro::Case::Flow: 61606.3 i/s # Micro::Case::Safe::Flow: 60688.3 i/s - same-ish: difference falls within error # Interactor::Organizer: 48598.2 i/s - 1.27x slower\ ```
Failure results - Show the full benchmark/ips results. ```ruby # Warming up -------------------------------------- # Interactor::Organizer 2.209k i/100ms # Micro::Case::Flow 11.508k i/100ms # Micro::Case::Safe::Flow 11.605k i/100ms # Calculating ------------------------------------- # Interactor::Organizer 22.592k (± 2.8%) i/s - 114.868k in 5.088685s # Micro::Case::Flow 123.629k (± 2.9%) i/s - 621.432k in 5.030844s # Micro::Case::Safe::Flow 123.862k (± 3.0%) i/s - 626.670k in 5.064097s # Comparison: # Micro::Case::Safe::Flow: 123862.4 i/s # Micro::Case::Flow: 123629.3 i/s - same-ish: difference falls within error # Interactor::Organizer: 22592.2 i/s - 5.48x slower ```
https://github.com/serradura/u-case/tree/master/benchmarks/flow ### Comparisons Check it out implementations of the same use case with different gems/abstractions. * [interactor](https://github.com/serradura/u-case/blob/master/comparisons/interactor.rb) * [u-case](https://github.com/serradura/u-case/blob/master/comparisons/u-case.rb) [⬆️ Back to Top](#table-of-contents-) ## Examples ### 1️⃣ Rails App (API) > This project shows different kinds of architecture (one per commit), and in the last one, how to use the Micro::Case gem to handle the application business logic. > > Link: https://github.com/serradura/from-fat-controllers-to-use-cases ### 2️⃣ CLI calculator > Rake tasks to demonstrate how to handle user data, and how to use different failure types to control the program flow. > > Link: https://github.com/serradura/u-case/tree/master/examples/calculator ### 3️⃣ Users creation > An example of a use case flow that define steps to sanitize, validate, and persist its input data. > > Link: https://github.com/serradura/u-case/blob/master/examples/users_creation.rb ### 4️⃣ Rescuing exception inside of the use cases > Link: https://github.com/serradura/u-case/blob/master/examples/rescuing_exceptions.rb [⬆️ Back to Top](#table-of-contents-) ## Development After checking out the repo, run `bin/setup` to install dependencies. Then, run `./test.sh` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment. To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org). ## Contributing Bug reports and pull requests are welcome on GitHub at https://github.com/serradura/u-case. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct. ## License The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT). ## Code of Conduct Everyone interacting in the Micro::Case project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/serradura/u-case/blob/master/CODE_OF_CONDUCT.md).