Protorails is an easy way to handle Protocol Buffers in Rails.

It has two major dependencies:

• ruby_protobuf
• protojson

Getting Started

Protorails handles all the Rails related stuff to be able to use Protocol Buffers specification tightly in Rails.

Protorails shall be used as any another dependency in a Rails application, including it in the Gemfile file, in an application that wants to use protojson to communicate with a third party.

Add as dependency

In your Rails 3 project, you should modify your Gemfile with this line:

gem 'protorails'

Currently protorails has not been published yet, so please use directly this github repository:

gem 'protorails', :git => 'git@github.com:juandebravo/protorails.git'

Install

Protorails needs to define new mime types and renderers. This can be done executing the following command:

rake generate protorails:install

This command will include the required configuration to allow the protojson specific formats:

render indexed: object 
render tagmap: object

A client request can specify the desired data format as usual, including the Accept HTTP header or including the format as a suffix in the URI. This command defines also two new supported formats:

application/indexed
    => curl -H "Accept: application/indexed" http://localhost:3000/index
    => curl http://localhost:3000/index.indexed

application/tagmap
=> curl -H "Accept: application/tagmap" http://localhost:3000/index
=> curl http://localhost:3000/index.tagmap

Generate a proto model (WIP...)

To be done...

rake generate protorails:model file.proto model

This command will compile the proto definitions to ruby classes (using the ruby_protobuf gem).

If no model is provided, all the messages in the proto file will be compiled. If a model is provided, this command should generate only that specific model

Generate a scaffold (WIP...)

To be done...

rake generate protorails:scaffold file.proto model

This command will compile the proto and generate a controller to handle CRUD operations per each message:

• create: POST that receives a proto and stores in DB using an AR model named as the proto model. The proto model shall include a helper to convert the objet to the AR model (pretty easy as AR model defines the constructor with a Hash of key-value attributes).

• show: GET that receives the proto primary identifier, retrieves it from DB using an AR model, populates the proto message and returns using the specified format

• update: PUT...

• destroy: DELETE...

• index: GET that receives a specific parameter (a valid proto message attribute), retrieves one or more objects from DB using AR, populates the proto message(s) and returns using the specified format.

Forthcoming features

• be ORM agnostic: DataMapper, mongoId... instead of AR

• create also the DB model when compiling the proto definition

• specify the relation Proto Model <-> DB Model. i.e.

  rake generate protorails:scaffold bluevia.proto Content Data => the Content proto message is related to Data DB model.