Service result

Each service call returns a result (unless an exception is thrown). The result is either successful or failed.

Successful result

A successful result indicates all operations completed without problems.

Example:

service_result = UsersService::Accept.call(user: User.first)

Returns:

# => <ApplicationService::Result @failure?=false, @success?=true, @user=..., @user?=true>

Failed result

A failed result indicates an expected problem occurred internally. Expected problems don't throw exceptions—they're triggered via fail! methods.

Failed results only occur when using the .call method. This enables processing responses from external APIs.

Example result on failure:

# => <ApplicationService::Result @error=There is some problem with the user, @failure?=true, @success?=false>

Result content

Result contains data regardless of outcome.

On success, all output attributes are available. The success? and failure? helper methods determine the outcome.

service_result = UsersService::Accept.call(user: User.first)

service_result.success? # => true
service_result.failure? # => false

On failure, Result also contains error with the full error description.

service_result = UsersService::Accept.call(user: User.first)

service_result.success? # => false
service_result.failure? # => true

service_result.error
# => #<ApplicationService::Exceptions::Failure: There is some problem with the user>

Learn more about service failures here.

Result processing

Process the result after calling via call.

Two options: success?/failure? methods or on_success/on_failure hooks.

Methods

Method success?

service_result = NotificatorService::Slack::Error::Send.call(...)

return if service_result.success?

fail!(
  message: "The message was not sent to Slack",
  meta: { reason: service_result.error.message }
)

Method failure?

Pass a type to failure? to check specific failure types. See failure types. Default type is all (matches any failure type).

service_result = NotificatorService::Slack::Error::Send.call(...)

return unless service_result.failure?

fail!(
  message: "The message was not sent to Slack", 
  meta: { reason: service_result.error.message }
)

Check for a specific failure type:

service_result = NotificatorService::Slack::Error::Send.call(...)

return unless service_result.failure?(:validation)

fail!(
    message: "The message was not sent to Slack",
    meta: { reason: service_result.error.message }
)

Predicate methods provide convenient type checking:

WARNING

Result output attributes also have predicate methods. Avoid naming conflicts.

service_result = NotificatorService::Slack::Error::Send.call(...)

return unless service_result.all?

fail!(
  message: "The message was not sent to Slack",
  meta: { reason: service_result.error.message }
)

Hooks

Alternative approach to result processing:

NotificatorService::Slack::Error::Send
  .call(...)
  .on_failure do |exception:| 
    fail!(
      message: "The message was not sent to Slack", 
      meta: { reason: exception.message }
    )
  end

The on_success method provides outputs argument with all output attributes. Pass a type to on_failure:

NotificatorService::Slack::Error::Send
  .call(...)
  .on_success do |outputs:|
    notification.update!(original_data: outputs.response)
  end.on_failure(:all) do |exception:| 
    fail!(
      message: "The message was not sent to Slack", 
      meta: { reason: exception.message }
    )
  end