Service result

After the call, the service has the result of its work, if an exception was not thrown before. The result of the work can be successful or failure.

Successful result

A successful result is the result of the service when everything inside went without any problems.

In that case, this example:

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

Will return this:

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

Failed result

A failed result is the result of a service running when an expected problem occurred internally. An expected problem means that an exception was not thrown, and the problem that arose, for example, was caused through one of the fail! methods.

A failed service result can only be present when called via the .call method. This is necessary, for example, to be able to process the result of a response from an external API.

An example of the result when a problem occurs:

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

Result content

Result regardless of success or failure has a data set.

Upon successful operation, all output attributes are available, and the success? and failure? helper methods are also available, which can help determine the scenario for further work.

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

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

If the service fails, Result will also contain error with a full description of the error.

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>

You can learn more about the unsuccessful operation of the service here.

Result processing

After calling a service via call, you can process its result.

There are two options for this - using the success? and failure? methods or using the on_success and on_failure hooks.

Methods

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

return if service_result.success? # or `unless service_result.failure?`

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

You can pass a type to the failure? method. You can find out more about the types here. This gives you the opportunity to specify the type you are interested in when handling a failed result. By default, type is all, which means any type fails, including your own types.

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

return unless service_result.failure?(:all)

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

Hooks

This is an alternative way to process the result.

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 has an outputs argument that provides access to all output attributes.

You can also pass a type to the on_failure method.

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