Skip to main content

Steps evaluation table

This page contains a table of demonstrative examples of how different step combinations are evaluated in services.

It is especially useful for newcomers who are not familiar with the Convenient Service DSL yet.

Before moving to the concrete examples, let's define some simple services that we are going to reuse.

class SuccessService
  include ConvenientService::Standard::Config

  def result
    success
  end
end

As you can see, the SuccessService is just a regular service that always returns a success result.

class FailureService
  include ConvenientService::Standard::Config

  def result
    failure
  end
end

In turn, the FailureService returns a failure result all the time.

class ErrorService
  include ConvenientService::Standard::Config

  def result
    error
  end
end

And finally, the ErrorService returns an error result whenever it is invoked.

info

All the examples on this page are using service steps.

But it is also perfectly valid to use corresponding method steps in them.

The behavior stays the same for both cases.

Consider the following snippet.

class Service
  include ConvenientService::Standard::Config

  step SuccessService # 0 - Evaluated.

  step FailureService # 1 - Evaluated.

  step ErrorService # 2 - Skipped.
end

Service.result
# => <Service::Result status: :failure>

Service.result.step
# => <Service::Step service: FailureService>

Service.result.step.index
# => 1

Its "equivalent" with the methods steps is the code below.

class Service
  include ConvenientService::Standard::Config

  step :success_method # 0 - Evaluated.

  step :failure_method # 1 - Evaluated.

  step :error_method # 2 - Skipped.

  def success_method
    success
  end

  def failure_method
 failure
  end

  def error_method
 error
  end
end

Service.result
# => <Service::Result status: :failure>

Service.result.step
# => <Service::Step method: :failure_method>

Service.result.step.index
# => 1

Both of them have the same evaluated and skipped steps.

Service without steps​

Example:

class Service
  include ConvenientService::Standard::Config

  def result # Evaluated.
    success
  end
end

Outcome:

Service.result
# => <Service::Result status: :success>
Service.result.step
# => nil

Service with a step that has a success result​

Example:

class Service
  include ConvenientService::Standard::Config

  step SuccessService # Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :success>
Service.result.step
# => <Service::Step service: SuccessService>
Service.result.step.index
# => 0

Service with a step that has a failure result​

Example:

class Service
  include ConvenientService::Standard::Config

  step FailureService # Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :failure>
Service.result.step
# => <Service::Step service: FailureService>
Service.result.step.index
# => 0

Service with a step that has an error result​

Example:

class Service
  include ConvenientService::Standard::Config

  step ErrorService # Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 0

Service with a negated step that has a success result​

Example:

class Service
  include ConvenientService::Standard::Config

  not_step  SuccessService # Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :failure message: "Original `result` is `success`">
Service.result.step
# => <Service::Step service: SuccessService>
Service.result.step.index
# => 0
info

Negation of a success result is a failure result.

Service with a negated step that has a failure result​

Example:

class Service
  include ConvenientService::Standard::Config

  not_step  FailureService # Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :success message: "Original `result` is `failure`">
Service.result.step
# => <Service::Step service: FailureService>
Service.result.step.index
# => 0
info

Negation of a failure result is a success result.

Service with a negated step that has an error result​

Example:

class Service
  include ConvenientService::Standard::Config

  not_step  ErrorService # Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 0
info

The error results are semantically close to the exceptions.

That is why they do not have negated results.

Service with multiple consecutive steps, all with a success result​

Example:

class Service
  include ConvenientService::Standard::Config

  step SuccessService # 0 - Evaluated.

  step SuccessService # 1 - Evaluated.

  step SuccessService # 2 - Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :success>
Service.result.step
# => <Service::Step service: SuccessService>
Service.result.step.index
# => 2

Service with multiple consecutive steps, last with failure result​

Example:

class Service
  include ConvenientService::Standard::Config

  step SuccessService # 0 - Evaluated.

  step SuccessService # 1 - Evaluated.

  step FailureService # 2 - Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :failure>
Service.result.step
# => <Service::Step service: FailureService>
Service.result.step.index
# => 2

Service with multiple consecutive steps, last with error result​

Example:

class Service
  include ConvenientService::Standard::Config

  step SuccessService # 0 - Evaluated.

  step SuccessService # 1 - Evaluated.

  step ErrorService # 2 - Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 2

Service with multiple consecutive steps, intermediate with failure result​

Example:

class Service
  include ConvenientService::Standard::Config

  step SuccessService # 0 - Evaluated.

  step FailureService # 1 - Evaluated.

  step SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :failure>
Service.result.step
# => <Service::Step service: FailureService>
Service.result.step.index
# => 1
info

For the consecutive steps, there are no differences between the steps that have failure and error results.

Both of them stop the sequence immediately and skip the rest of the steps.

Service with multiple consecutive steps, intermediate with error result​

Example:

class Service
  include ConvenientService::Standard::Config

  step SuccessService # 0 - Evaluated.

  step ErrorService # 1 - Evaluated.

  step SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 1
info

For the consecutive steps, there are no differences between the steps that have failure and error results.

Both of them stop the sequence immediately and skip the rest of the steps.

Service with multiple consecutive steps, first with a failure result​

Example:

class Service
  include ConvenientService::Standard::Config

  step FailureService # 0 - Evaluated.

  step SuccessService # 1 - Skipped.

  step SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :failure>
Service.result.step
# => <Service::Step service: FailureService>
Service.result.step.index
# => 0
info

For the consecutive steps, there are no differences between the steps that have failure and error results.

Both of them stop the sequence immediately and skip the rest of the steps.

Service with multiple consecutive steps, first with an error result​

Example:

class Service
  include ConvenientService::Standard::Config

  step ErrorService # 0 - Evaluated.

  step SuccessService # 1 - Skipped.

  step SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 0
info

For the consecutive steps, there are no differences between the steps that have failure and error results.

Both of them stop the sequence immediately and skip the rest of the steps.

Service with multiple alternative steps, all with a success result​

Example:

class Service
  include ConvenientService::Standard::Config

  step SuccessService # 0 - Evaluated.

  or_step  SuccessService # 1 - Skipped.

  or_step  SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :success>
Service.result.step
# => <Service::Step service: SuccessService>
Service.result.step.index
# => 0

Service with multiple alternative steps, first with failure result​

Example:

class Service
  include ConvenientService::Standard::Config

  step FailureService # 0 - Evaluated.

  or_step  SuccessService # 1 - Evaluated.

  or_step  SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :success>
Service.result.step
# => <Service::Step service: SuccessService>
Service.result.step.index
# => 1
info

For the alternative steps, only the steps with error results stop the sequence.

The failure steps initiate the next available or_step.

Service with multiple alternative steps, first with an error result​

Example:

class Service
  include ConvenientService::Standard::Config

  step ErrorService # 0 - Evaluated.

  or_step  SuccessService # 1 - Skipped.

  or_step  SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 0
info

For the alternative steps, only the steps with error results stop the sequence.

The failure steps initiate the next available or_step.

Service with multiple alternative steps, first and intermediate with failure result​

Example:

class Service
  include ConvenientService::Standard::Config

  step FailureService # 0 - Evaluated.

  or_step  FailureService # 1 - Evaluated.

  or_step  SuccessService # 2 - Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :success>
Service.result.step
# => <Service::Step service: SuccessService>
Service.result.step.index
# => 2
info

For the alternative steps, only the steps with error results stop the sequence.

The failure steps initiate the next available or_step.

Service with multiple alternative steps, first and intermediate with error result​

Example:

class Service
  include ConvenientService::Standard::Config

  step ErrorService # 0 - Evaluated.

  or_step  ErrorService # 1 - Skipped.

  or_step  SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 0
info

For the alternative steps, only the steps with error results stop the sequence.

The failure steps initiate the next available or_step.

Service with multiple alternative steps, first with failure result, intermediate with error result​

Example:

class Service
  include ConvenientService::Standard::Config

  step FailureService # 0 - Evaluated.

  or_step  ErrorService # 1 - Evaluated.

  or_step  SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 1
info

For the alternative steps, only the steps with error results stop the sequence.

The failure steps initiate the next available or_step.

Service with multiple alternative steps, first with error result, intermediate with failure result​

Example:

class Service
  include ConvenientService::Standard::Config

  step ErrorService # 0 - Evaluated.

  or_step  FailureService # 1 - Skipped.

  or_step  SuccessService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 0
info

For the alternative steps, only the steps with error results stop the sequence.

The failure steps initiate the next available or_step.

Service with multiple alternative steps, all with a failure result​

Example:

class Service
  include ConvenientService::Standard::Config

  step FailureService # 0 - Evaluated.

  or_step  FailureService # 1 - Evaluated.

  or_step  FailureService # 2 - Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :failure>
Service.result.step
# => <Service::Step service: FailureService>
Service.result.step.index
# => 2
info

For the alternative steps, only the steps with error results stop the sequence.

The failure steps initiate the next available or_step.

Service with multiple alternative steps, all with an error result​

Example:

class Service
  include ConvenientService::Standard::Config

  step ErrorService # 0 - Evaluated.

  or_step  ErrorService # 1 - Skipped.

  or_step  ErrorService # 2 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 0
info

For the alternative steps, only the steps with error results stop the sequence.

The failure steps initiate the next available or_step.

Complex combination of consecutive steps, negated steps, and alternative steps without evaluated errors.​

Example:

class Service
  include ConvenientService::Standard::Config

  step FailureService # 0 - Evaluated.

  or_step  FailureService # 1 - Evaluated.

  or_step  SuccessService # 2 - Evaluated.

  step SuccessService # 3 - Evaluated.

  and_step SuccessService # 4 - Evaluated.

  and_not_step FailureService # 5 - Evaluated.

  step FailureService # 6 - Evaluated.

  or_step  SuccessService # 7 - Evaluated.

  step FailureService # 8 - Evaluated.

  or_step  FailureService # 9 - Evaluated.

  or_not_step FailureService # 10 - Evaluated.

  or_step  ErrorService # 11 - Skipped.

  step SuccessService # 12 - Evaluated.

  not_step  SuccessService # 13 - Evaluated.

  or_step  FailureService # 14 - Evaluated.

  or_not_step FailureService # 15 - Evaluated.

  or_step  FailureService # 16 - Skipped.

  or_step  ErrorService # 17 - Skipped.

  or_step  SuccessService # 18 - Skipped.

  step SuccessService # 19 - Evaluated.

  and_step SuccessService # 20 - Evaluated.
end

Outcome:

Service.result
# => <Service::Result status: :success>
Service.result.step
# => <Service::Step service: SuccessService>
Service.result.step.index
# => 20
info

The and_step directive is just an alias to the usual step.

The only difference is that it can not be used as the first step.

info

The and_not_step directive is just an alias to the usual not_step.

The only difference is that it can not be used as the first step.

info

The or_not_step directive works like the or_step, but it firstly negates its result.

Complex combination of consecutive steps, negated steps, and alternative steps with evaluated errors.​

Example:

class Service
  include ConvenientService::Standard::Config

  step FailureService # 0 - Evaluated.

  or_step  FailureService # 1 - Evaluated.

  or_step  SuccessService # 2 - Evaluated.

  step SuccessService # 3 - Evaluated.

  and_step SuccessService # 4 - Evaluated.

  and_not_step FailureService # 5 - Evaluated.

  step FailureService # 6 - Evaluated.

  or_step  ErrorService # 7 - Evaluated.

  step FailureService # 8 - Skipped.

  or_step  FailureService # 9 - Skipped.

  or_not_step FailureService # 10 - Skipped.

  or_step  ErrorService # 11 - Skipped.

  step SuccessService # 12 - Skipped.

  not_step  SuccessService # 13 - Skipped.

  or_step  FailureService # 14 - Skipped.

  or_not_step FailureService # 15 - Skipped.

  or_step  FailureService # 16 - Skipped.

  or_step  ErrorService # 17 - Skipped.

  or_step  SuccessService # 18 - Skipped.

  step SuccessService # 19 - Skipped.

  and_step SuccessService # 20 - Skipped.
end

Outcome:

Service.result
# => <Service::Result status: :error>
Service.result.step
# => <Service::Step service: ErrorService>
Service.result.step.index
# => 7
info

The first evaluated error step is always a sequence stopper.

No matter how many other steps are coming after it.

No matter which exact types they have.

None of them are executed, they are just skipped.

In other words, the first evaluated error step is always the whole service's last evaluated step in any circumstances.