FMParser

FieldMask Parser. If you want to know more about FieldMask, please see https://developers.google.com/protocol-buffers/docs/reference/google.protobuf#fieldmask .

Installation

Add this line to your application's Gemfile:

gem 'fmparser'

And then execute:

$ bundle

Or install it yourself as:

$ gem install fmparser

Usage

FMParser.parse parses FieldMask parameter and returns a FMParser::MessageNode object.

For example, suppose you have the protobuf message classes shown below:

syntax = "proto3";
package msg;

message User {
  Operation op = 1;
  int64 id = 2;
  repeated Name names =3;
  Job job = 4;
}

message Name {
  Operation op = 1;
  int64 id = 2;
  string first_name = 3;
  string middle_name = 4;
  string last_name = 5;
  string language = 6;
}

message Job {
  Operation op = 1;
  int64 id = 2;
  string company = 3;
}

enum Operation {
  OPERATION_UNSPECIFIED = 0;
  CREATE = 1;
  UPDATE = 2;
  DELETE = 3;
}

Then, you can parse paths array of strings with root protobuf message class.

[1] pry(main)> f = FMParser.parse(paths: ["op", "id", "names.first_name", "names.last_name"], root: Msg::User)
=> #<FMParser::MessageNode:0x00007f7fc9848168
 @enums=[#<FMParser::EnumNode:0x00007f7fc98489b0 @label=:optional, @name=:op, @type=Msg::Operation>],
 @label=nil,
 @messages=
  [#<FMParser::MessageNode:0x00007f7fc9848208
    @enums=[],
    @label=:repeated,
    @messages=[],
    @name=:names,
    @scalars=
     [#<FMParser::ScalarNode:0x00007f7fc98484b0 @label=:optional, @name=:first_name, @type=:string>,
      #<FMParser::ScalarNode:0x00007f7fc98482a8 @label=:optional, @name=:last_name, @type=:string>],
    @type=Msg::Name>],
 @name=nil,
 @scalars=[#<FMParser::ScalarNode:0x00007f7fc9848820 @label=:optional, @name=:id, @type=:int64>],
 @type=Msg::User>

[2] pry(main)> f.field_names
=> [:id, :op, :names]

[3] pry(main)> f.has?(:id)
=> true

[4] pry(main)> f.has?(:names)
=> true

[5] pry(main)> f.has?(:job)
=> false

[6] pry(main)> f.get_child(:names)
=> #<FMParser::MessageNode:0x00007f7fc9848208
 @enums=[],
 @label=:repeated,
 @messages=[],
 @name=:names,
 @scalars=
  [#<FMParser::ScalarNode:0x00007f7fc98484b0 @label=:optional, @name=:first_name, @type=:string>,
   #<FMParser::ScalarNode:0x00007f7fc98482a8 @label=:optional, @name=:last_name, @type=:string>],
 @type=Msg::Name>

[7] pry(main)> f.get_child(:names).field_names
=> [:first_name, :last_name]

Development

After checking out the repo, run bin/setup to install dependencies. Then, run bundle exec rspec 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.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/wantedly/fmparser.

License

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