discourse/plugins/chat/lib/service_runner.rb
Loïc Guitaut b8762172e4 DEV: Allow with_service in jobs
This patch introduces a new `ServiceJob` class allowing the use of
`with_service` in jobs.

This way, it’s easier to use the chat service objects in jobs and
provides the same level of functionality than the one we have in
controllers.
2023-02-23 09:28:53 +01:00

117 lines
3.7 KiB
Ruby

# frozen_string_literal: true
#
# = Chat::ServiceRunner
#
# This class is to be used via its helper +with_service+ in any class. Its
# main purpose is to ease how actions can be run upon a service completion.
# Since a service will likely return the same kind of things over and over,
# this allows us to not have to repeat the same boilerplate code in every
# object.
#
# There are several available actions and we can add new ones very easily:
#
# * +on_success+: will execute the provided block if the service succeeds
# * +on_failure+: will execute the provided block if the service fails
# * +on_failed_policy(name)+: will execute the provided block if the policy
# named `name` fails
# * +on_failed_contract(name)+: will execute the provided block if the contract
# named `name` fails
# * +on_model_not_found(name)+: will execute the provided block if the service
# fails and its model is not present
#
# @example In a controller
# def create
# with_service MyService do
# on_success do
# flash[:notice] = "Success!"
# redirect_to a_path
# end
# on_failed_policy(:a_named_policy) { redirect_to root_path }
# on_failure { render :new }
# end
# end
#
# @example In a job (inheriting from +ServiceJob+)
# def execute(args = {})
# with_service(MyService, **args) do
# on_success { Rails.logger.info "SUCCESS" }
# on_failure { Rails.logger.error "FAILURE" }
# end
# end
#
# The actions will be evaluated in the order they appear. So even if the
# service will ultimately fail with a failed policy, in this example only the
# +on_failed_policy+ action will be executed and not the +on_failure+ one.
# The only exception to this being +on_failure+ as it will always be executed
# last.
#
class Chat::ServiceRunner
# @!visibility private
NULL_RESULT = OpenStruct.new(failure?: false)
# @!visibility private
AVAILABLE_ACTIONS = {
on_success: -> { result.success? },
on_failure: -> { result.failure? },
on_failed_policy: ->(name = "default") { failure_for?("result.policy.#{name}") },
on_failed_contract: ->(name = "default") { failure_for?("result.contract.#{name}") },
on_model_not_found: ->(name = "model") { failure_for?("result.model.#{name}") },
}.with_indifferent_access.freeze
# @!visibility private
attr_reader :service, :object, :dependencies
delegate :result, to: :object
# @!visibility private
def initialize(service, object, **dependencies)
@service = service
@object = object
@dependencies = dependencies
@actions = {}
end
# @param service [Class] a class including {Chat::Service::Base}
# @param block [Proc] a block containing the steps to match on
# @return [void]
def self.call(service, object, **dependencies, &block)
new(service, object, **dependencies).call(&block)
end
# @!visibility private
def call(&block)
instance_eval(&block)
object.run_service(service, dependencies)
# Always have `on_failure` as the last action
(
actions
.except(:on_failure)
.merge(actions.slice(:on_failure))
.detect { |name, (condition, _)| condition.call } || [-> {}]
).flatten.last.call
end
private
attr_reader :actions
def failure_for?(key)
(object.result[key] || NULL_RESULT).failure?
end
def add_action(name, *args, &block)
actions[[name, *args].join("_").to_sym] = [
-> { instance_exec(*args, &AVAILABLE_ACTIONS[name]) },
-> { object.instance_eval(&block) },
]
end
def method_missing(method_name, *args, &block)
return super unless AVAILABLE_ACTIONS[method_name]
add_action(method_name, *args, &block)
end
def respond_to_missing?(method_name, include_private = false)
AVAILABLE_ACTIONS[method_name] || super
end
end