Gruf Commander

Assists with request/command-style syntax and separated validation layer in gruf requests.

Add this line to your application's Gemfile:

gem 'gruf-commander'

And then execute:

$ bundle

Or install it yourself as:

$ gem install gruf-commander

If you're on a Rails version prior to 3/4, or utilizing ActiveModel < 5, you'll need to install the active_model-errors_details gem.

gem 'active_model-errors_details'

Gruf Commander supports the Command/Request design pattern. You create Request classes that perform validation, and then submit themselves to a Command. The Command class then performs the business logic by interacting with internal layers of the application, such as the service, DTO, or repository layers.

First, in your gruf initializer, add the interceptor:

Gruf.configure do |c|
  c.interceptors.use(Gruf::Commander::RequestValidationInterceptor)
end

Then you'll create your command and request classes:

class CreateBoxCommand < Gruf::Commander::Command
  def call(request)
    Box.create!(width: request.width, height: request.height)
  end
end


class CreateBoxRequest < Gruf::Commander::Request
  attr_reader :width
  attr_reader :height
  
  validate :validate_width, :validate_height
  
  def initialize(width:, height:)
    @width = width
    @height = height
    super(command: CreateBoxCommand.new)
  end
  
  private
  
  def validate_width
    return if @width.to_i > 0    
    errors.add(:width, :invalid_width, message: 'Please enter a valid width!')
  end
  
  def validate_height
    return if @height.to_i > 0    
    errors.add(:height, :invalid_height, message: 'Please enter a valid height!')
  end
end

Then, in your gruf controller:

def create_box
  request = CreateBoxRequest.new(
    width: request.message.width.to_i,
    height: request.message.height.to_i,
  )
  box = request.submit!
  Rpc::CreateBoxResponse.new(
    box: Rpc::Box.new(height: box.height, width: box.width)
  )
end

Gruf Commander will automatically handle the validation errors to push back to the grpc server, properly sending an GRPC::InvalidArgument exception should validation fail.

You can configure the request validation options:

Gruf Commander works very well with DI systems such as dry-rb, since Request objects can simply just provide accessors to modify their attributes, and commands are simple plain classes that can have no strict contract on initialization.

We recommend using a DI system (such as dry-rb) to use with Gruf Commander, as it helps with testing and refactoring in more complex applications.

Tests are run via rspec:

bundle exec rspec

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