Gruf Commander

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

Installation

Add this line to your application's Gemfile:

gem 'gruf-commander'

And then execute:

$ bundle

Or install it yourself as:

$ gem install gruf-commander

Rails < 5 usage

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'

Usage

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.

Configuration

You can configure the request validation options:

Config Name	Description	Default
invalid_request_error_code	Sets the gRPC error code sent back on failed validation.	:invalid_argument
invalid_request_app_error_code	Sets the app error code sent back on failed validation.	:invalid_request
invalid_request_message	Sets the error message sent back on failed validation.	Invalid Request

Dependency Injection

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.

Testing

Tests are run via rspec:

bundle exec rspec

License

Copyright (c) 2018-present, BigCommerce Pty. Ltd. All rights reserved

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.