Pbbuilder

PBBuilder generates Protobuf Messages with a simple DSL similar to the JBuilder gem.

This gem only supports Rails 7.0 and Rails 7.2, 7.1 is not supported.

There currently is a regression in ActionView (the part of Rails which renders) that forces rendered objects into strings, but for Pbbuilder we need the raw objects. This is only present in Rails 7.1, and a fix is released in Rails 7.2. rails/rails#51023

It might work on rails v6 (it worked previously), but we don't guarantee that and don't test against these versions anymore.

We don't aim to have 100% compitability and coverage with jbuilder gem, but we closely follow jbuilder's API design to maintain familiarity.

Due to the protobuf message implementation, there is absolutely no need to implement support for deep_format_keys!, key_format!, key_format, deep_format_keys, ignore_nil!, ignore_nil!, nil. So those would never be added.

The main difference is that it can use introspection to figure out what kind of protobuf message it needs to create.

This is an example .proto message.

message Person {
  string name = 1;
  repeated Person friends = 2;
}

The following .pb file would generate a message of valid Person type.

person = RPC::Person.new

Pbbuilder.new(person) do |pb|
  pb.name "Hello"
  pb.friends [1, 2, 3] do |number|
    pb.name "Friend ##{number}"
  end
end

Under the hood, this DSL is using method_missing and set! methods. But there are other methods and features to use.

The following _account.pb.pbbuilder partial:

pb.id account.id
pb.phone_number account.phone_number
pb.tag account.tag

can be rewritten to a shorter version with the use of extract!.

pb.extract! account, :id, :phone_number, :tag

Given partial _account.pb.pbuilder:

pb.name account.name
pb.registration_date account.created_at

Using partial while passing a variable to it

pb.account partial: "account", account: @account

Here is a way to use partials with a collection while passing a variable to it

pb.accounts @accounts, partial: "account", as: account

There are two different methods to render a collection. One that uses ActiveView::CollectionRenderer

pb.friends partial: "racers/racer", as: :racer, collection: @racers

pb.friends "racers/racer", as: :racer, collection: @racers

And there are other ways, that don't use CollectionRenderer

pb.partial! @racer, racer: Racer.new(123, "Chris Harris", friends)

pb.friends @friends, partial: "racers/racer", as: :racer

It uses Rails.cache and works like caching in HTML templates:

pb.cache! "cache-key", expires_in: 10.minutes do
  pb.name @person.name
end

You can also conditionally cache a block by using cache_if! like this:

pb.cache_if! !admin?, "cache-key", expires_in: 10.minutes do
  pb.name @person.name
end

Fragment caching currently works through ActionView::CollectionRenderer and can only be used with the following syntax:

pb.friends partial: "racers/racer", as: :racer, collection: @racers, cached: true

pb.friends "racers/racer", as: :racer, collection: @racers, cached: true

Add this line to your application's Gemfile:

gem 'pbbuilder'

And then execute:

$ bundle

Or install it yourself as:

$ gem install pbbuilder

When debugging, make sure to prepend ::Kernel to any calls such as puts as otherwise the code will think you're trying to add another attribute into protobuf object.

In case you're looking to use breakpoints (for debugging purposes via binding.pry for instance), let Pbbuilder inherit from Object instead of BasicObject] Seen in: Pbbuilder Errors

Running bundle exec appraisal rake test locally will run the entire testsuit with all versions of rails. To run tests only for a certain rails version do the following bundle exec appraisal rails-7-0 rake test

To run only one tests from file - use m utility. Like this: bundle exec appraisal rails-7-0 m test/pbbuilder_template_test.rb:182

Everyone is welcome to contribute.

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