Erlash

Erlash simplifies and abstracts the hard part of creating meaningful errors. The ruby implementation for errors is hard and tedious to create errors that explain what exactly the error was. In production you can find errors that do not explain the context and gives you no clue what's going on.

You can find errors like:

ValidationError:
  email already token

Wouldn't be nice to have more information about the error?

example:

RequestError:
 Problem:
   User is unable to update his email
 Summary:
   Validation errors: email already token
 Context:
   - request_id: `123`
   - user: { id: 1, email: `mail@example.com` }
   - endpoint: `PUT /users/1`
   - params: { email: `another@email.com` }

To build this kind of errors with the standard library is very tedious and not reusable. With erlash creating meaningful errors is easy.

Add this line to your application's Gemfile:

gem 'erlash'

And then execute:

$ bundle

Or install it yourself as:

$ gem install erlash

class MyError < Erlash::Base; end

raise Myerror, { user_id: 1, request_id: 120, controller: 'users_controller' }
# Myerror:
#   - user_id: 1
#   - request_id: 120
#   - controller: `users_controller`

class MyError < Erlash::Base
  problem -> { |context| "Please user `#{context[:user_id]}` be careful" }
  summary "This error usually happens when user is desperate for the bug"
  resolution -> { |context| "User.find(#{context[:user_id]}).fix" }
end

raise Myerror, { user_id: 1, request_id: 120, controller: 'users_controller' }
# Myerror:
#  Problem:
#    Please user `1` be careful
#  Summary:
#    This error usually happens when user is desperate for the bug
#  Resolution:
#    User.find(1).fix
#  Context:
#    - user_id: 1
#    - request_id: 120
#    - controller: `users_controller`

Erlash is fully customizable. You can add formatters for your objects or override the default ones.

Create your formatter:

Create a class that inherits from Erlash::TemplateFormatter and add a format method to it.

class MyUserFormatter < Erlash::TemplateFormatter
  def format
    "And the name is: #{object.name}"
  end
end

Register your formatter:

When registering a formatter you should provide the class is going to format as first argument. Arguments:

• class to be formatted. ex: User
• formatter for given class. ex: MyUserFormatter

Erlash.formatters.register(User, MyUserFormatter)

Erlash::TemplateFormatter

Accessible methods:

• object: is an instance of the registered class. in the example User instance

• format_elem: will try to find a formatter for given object if not will default to_s

  • args: [object]

example:

class User
  def email
    "mail@example.com"
  end
  def id; 1 end
  def errors
    "email already token"
  end
end

class Erlash::UserFormatter < Erlash::TemplateFormatter
  def format
    format_elem({
      id: object.id,
      email: object.email
    }) # it will be formatted by the registered formatter for Hash
  end
end

Erlash.formatters.register(User, Erlash::UserFormatter)

class RequestError < Erlash::Base
  problem "User is unable to update his email"
  summary do |context|
    "Validation errors: #{context[:user].errors}"
  end
end

raise RequestError.new(request_id: '123', user: User.new, endpoint: 'PUT /users/1', params: {email: "another@email.com"})
# RequestError:
#   Problem:
#     User is unable to update his email
#   Summary:
#     Validation errors: email already token
#   Context:
#     - request_id: `123`
#     - user: { id: 1, email: `mail@example.com` }
#     - endpoint: `PUT /users/1`
#     - params: { email: `another@email.com` }

Default formatters:

• Array => Erlash::ArrayFormatter
• Hash => Erlash::HashFormatter
• String => Erlash::StringFormatter

Custom Erlash classes:

• Erlash::Tip => Erlash::TipFormatter
• Erlash::Context => Erlash::ContextFormatter
• Erlash::MainArray => Erlash::MainArrayFormatter
• Erlash::MainHash => Erlash::MainHashFormatter

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/arturictus/erlash. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the Erlash project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.