Class: NextStation::Operation

Inherits:
Object
  • Object
show all
Extended by:
ClassMethods
Defined in:
lib/next_station/operation.rb,
lib/next_station/operation/node.rb,
lib/next_station/operation/errors.rb,
lib/next_station/operation/class_methods.rb

Overview

The core class for defining operations.

Operations are composed of steps and branches, and they return a NextStation::Result.

Defined Under Namespace

Modules: ClassMethods Classes: ErrorDefinition, ErrorsDSL, Halt, Node

Instance Method Summary collapse

Methods included from ClassMethods

branch, dependencies, depends, disable_result_schema, enforce_result_schema, error_definitions, errors, force_validation!, has_step?, loaded_plugins, plugin, process, result_at, result_class, result_key, result_schema, schema_enforced?, skip_validation!, step, steps, validate_with, validation_contract_class, validation_contract_instance, validation_enforced?

Constructor Details

#initialize(deps: {}) ⇒ Operation

Use ‘ .new(deps: …) ` to inject dependencies (e.g. test doubles).

Examples:

Example usage, simple initialization:

CreateUser.new

Example usage, ‘.new` with override of dependencies:

# Assuming Mailer is a class that sends emails:
# class CreateUser < NextStation::Operation
#   depends mailer: -> { Mailer.new }
#   # rest of the class definition
# end
#
# You can then inject the mock mailer in tests:
mock_mailer = mock('mailer')
CreateUser.new(deps: { mailer: mock_mailer })

Parameters:

  • deps (Hash) (defaults to: {}) —

    Allows to override the default dependencies.



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# File 'lib/next_station/operation.rb', line 35

def initialize(deps: {})
  @injected_deps = deps
  @resolved_deps = {}
end

Instance Method Details

#call(params = {}, context = {}) ⇒ NextStation::Result

Executes the operation.

Examples:

operation.call(name: ‘john’, age: 25)

operation.call(params: { name: ‘john’, age: 25 }, context: { lang: :en })

Parameters:

  • params (Hash) (defaults to: {}) —

    Input parameters.

  • context (Hash) (defaults to: {}) —

    Execution context (e.g. :lang).

Returns:



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# File 'lib/next_station/operation.rb', line 60

def call(params = {}, context = {})
  monitor = NextStation.config.monitor

  monitor.publish('operation.start', operation: self.class.name, params: params, context: context)

  start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)

  if self.class.validation_enforced? && !self.class.has_step?(:validation)
    raise ValidationError, 'Validation is enforced but step :validation is missing from process block'
  end

  @state = State.new(params, context, self.class.loaded_plugins)
  lang = context[:lang] || :en

  self.class.loaded_plugins.each do |mod|
    mod.on_operation_start(self, @state) if mod.respond_to?(:on_operation_start)
  end

  begin
    @state = execute_nodes(self.class.steps, @state)
  rescue Halt => e
    result = if e.error
               Result::Failure.new(e.error)
             else
               definition = self.class.error_definitions[e.type]
               raise "Undeclared error type: #{e.type}" unless definition

               message = definition.resolve_message(lang, e.msg_keys)
               Result::Failure.new(
                 Result::Error.new(
                   type: e.type,
                   message: message,
                   help_url: definition.help_url,
                   details: e.details,
                   msg_keys: e.msg_keys
                 )
               )
             end

    self.class.loaded_plugins.each do |mod|
      mod.on_operation_stop(self, result) if mod.respond_to?(:on_operation_stop)
    end

    monitor.publish('operation.stop',
                    operation: self.class.name,
                    duration: duration(start_time),
                    result: result,
                    state: @state)
    return result
  rescue NextStation::ValidationError => e
    raise e
  rescue NextStation::Error => e
    raise e
  rescue StandardError => e
    result = Result::Failure.new(
      Result::Error.new(
        type: :exception,
        message: e.message,
        details: { backtrace: e.backtrace }
      )
    )

    self.class.loaded_plugins.each do |mod|
      mod.on_operation_stop(self, result) if mod.respond_to?(:on_operation_stop)
    end

    monitor.publish('operation.stop',
                    operation: self.class.name,
                    duration: duration(start_time),
                    result: result,
                    state: @state)
    return result
  end

  key = self.class.result_key || :result
  unless @state.key?(key)
    raise NextStation::MissingResultKeyError, "Missing result key #{key.inspect} in state. " \
                                             'Operations must set this key or use result_at to specify another one.'
  end

  result = Result::Success.new(
    @state[key],
    schema: self.class.result_class,
    enforced: self.class.schema_enforced?
  )

  self.class.loaded_plugins.each do |mod|
    mod.on_operation_stop(self, result) if mod.respond_to?(:on_operation_stop)
  end

  monitor.publish('operation.stop',
                  operation: self.class.name,
                  duration: duration(start_time),
                  result: result,
                  state: @state)
  result
end

#call_operation(state, operation_class, with_params:, store_result_in_key: nil) ⇒ NextStation::State

Calls another operation and integrates its result into the current state.

Parameters:

  • state (NextStation::State)
  • operation_class (Class, Object) —

    The operation to call.

  • with_params (Hash, Proc) —

    Params for the child operation.

  • store_result_in_key (Symbol, nil) (defaults to: nil) —

    Where to store the child’s result value.

Returns:



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# File 'lib/next_station/operation.rb', line 233

def call_operation(state, operation_class, with_params:, store_result_in_key: nil)
  params = with_params.is_a?(Proc) ? with_params.call(state) : with_params

  operation = if operation_class.is_a?(Class)
                operation_class.new(deps: @injected_deps)
              else
                operation_class
              end

  result = operation.call(params, state.context)

  if result.success?
    state[store_result_in_key] = result.value if store_result_in_key
    state
  else
    child_error = result.error
    raise Halt.new(error: child_error) unless self.class.error_definitions.key?(child_error.type)

    error!(
      type: child_error.type,
      msg_keys: child_error.msg_keys,
      details: child_error.details
    )

  end
end

#dependency(name) ⇒ Object

Resolves a dependency by name.

Parameters:

  • name (Symbol)

Returns:

  • (Object) —

    The resolved dependency.



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# File 'lib/next_station/operation.rb', line 43

def dependency(name)
  return @resolved_deps[name] if @resolved_deps.key?(name)

  if @injected_deps.key?(name)
    @resolved_deps[name] = @injected_deps[name]
  else
    default = self.class.dependencies.fetch(name)
    @resolved_deps[name] = default.is_a?(Proc) ? default.call : default
  end
end

#error!(type:, msg_keys: {}, details: {}) ⇒ Object

Halts the operation and returns a failure result.

Parameters:

  • type (Symbol)
  • msg_keys (Hash) (defaults to: {})
  • details (Hash) (defaults to: {})

Raises:



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# File 'lib/next_station/operation.rb', line 195

def error!(type:, msg_keys: {}, details: {})
  raise Halt.new(type: type, msg_keys: msg_keys, details: details)
end

#publish_log(level, message, payload = {}) ⇒ Object

Publishes a log event to the default monitor.

NextStation provides a built-in event system powered by dry-monitor to track user-defined logs. Inside your operation steps, you can use publish_log to broadcast custom events. These are automatically routed to the configured logger by default.

By default, NextStation logs to STDOUT using the standard Ruby Logger.

Examples:

publish_log :info, ‘simple log message’

publish_log :info, ‘log with custom payload’, user_id: 5, hello: ‘world’

Parameters:

  • level (Symbol) —

    The log level.

  • message (String) —

    The log message.

  • payload (Hash) (defaults to: {}) —

    Additional metadata for the log.

Options Hash (level):

  • :info (Symbol) —

    Informational message

  • :warn (Symbol) —

    Warning condition

  • :error (Symbol) —

    Error condition

  • :fatal (Symbol) —

    Fatal error

  • :debug (Symbol) —

    Debugging message



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# File 'lib/next_station/operation.rb', line 216

def publish_log(level, message, payload = {})
  NextStation.config.monitor.publish(
    'log.custom',
    level: level,
    message: message,
    operation: self.class.name,
    step_name: @state&.current_step,
    payload: payload
  )
end

#validation(state) ⇒ NextStation::State

Built-in step for performing validation.

Parameters:

Returns:

Raises:



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# File 'lib/next_station/operation.rb', line 161

def validation(state)
  contract_class = self.class.validation_contract_class
  raise ValidationError, 'Step :validation called but no contract defined via validate_with' unless contract_class

  return state unless self.class.validation_enforced?

  lang = state.context[:lang] || :en
  contract = self.class.validation_contract_instance
  result = contract.call(state.params)

  if result.success?
    state[:params] = result.to_h
    state
  else
    # Attempt to get localized errors from dry-validation, fallback to default if it fails
    # (e.g. if I18n is not configured for that language in dry-validation)
    validation_errors = begin
      result.errors(locale: lang).to_h
    rescue StandardError
      result.errors.to_h
    end

    error!(
      type: :validation,
      msg_keys: { errors: validation_errors }.merge(state.params),
      details: validation_errors
    )
  end
end