ruby on rails - validation and error-handling for service objects -

I have created a service item in the train to work as an interface between our app and our API.

I got this idea

Here is a small example:

  class packagecceptor def self.get_package (package_id) raise ArgumentError.new (" Package_id can not be zero ") if package_id.blank? Package = API :: get "/ packages / # {package_id}" package = JSON.parse package ,: symbolize_names = & gt; Unless the package.blank happens?   
 For assumptions:  
 
 I have to check all the inputs of zero or wrong type. Is there any way to easy verification? Maybe a rail extension?   
 For errors:  
 
 I can capture all API errors and then return zero to safely. But programmers using the service object may not know the meaning of zero.  
 I can catch API errors and raise another error which means that it is an extra effort to do all the tasks  
 The third option is to leave it and the programmer Handle all the errors from the API.   
 Let me know if you know a good pattern or if you have better suggestions for having an API interface.   
 
 
. As soon as you start complex cases (many logic, objects, etc.), then I start to tilt.  
 Refer to them (see "remove form object"). Sometimes use something like, to build service items. E.g.  
  requires 'active_model' to require 'virtus' class CreatePackage includes vertech in ActiveModel :: Validations attribute: name, string attribute: author, string Validates_presence_of: name, : To create the author def, ArgumentError.new ("Invalid Package") does not own unless Valid? Feedback = JSON.parse (API :: Post ("/ packages", auto attributes),: symbolize_names = & gt; true) package. New (answer) end-end class package includes Virtus attribute: id, integer attribute: name, string attribute: author, string and # example Service = CreatePackage.new (: name = & gt; "Tim Toms",: author = & gt; "Tim",) service.valid? # truth; If false, then service.errors package = service.create package.attributes # = & gt; See. {: Id = & gt; 123 ,: Name = & gt; "Tim Tom's",: Author = & gt; "Tim"} As an exception, I leave them for small tasks (like this service class). I'll wrap   if I'm writing something more important, however, a complete API client library.  
 I will never return zero like a network error, or bad or amazing feedback from the server both benefit from the obvious errors.  
 
 Finally, there is a much more complex approach that is called. Even if you do not use it, then there is a bunch of ideas about how to deal with service items, assumptions and results, which you can find interesting.  
  Edit : Also, check-out. In addition to simple and less comprehensive, like use_case