ProtoTS

Generate typescript interfaces from protobuf files

Summary

• ProtoTS
  • Summary
  • Installation
  • Usage
    • Options
    • Streams
    • Example file

Installation

npm install protots

Usage

ProtoTS exports only one method parse which can receive either a Buffer, a string with the file Path, the file string itself or a readable stream (of type Readable). And returns a promise with an object with two entries:

{
  toString: () => string,
  toFile: (path: string) => Promise<void>
}

So if you want to parse a file and get the string do this:

import {parse} from 'protots'
import fs from 'fs'
 
// From a buffer
const fileBuffer = fs.readFileSync('path/to/file')
const fileString = parse(fileBuffer).then(result => result.toString())
 
// From a stream
const fileStream = fs.createReadStream('path/to/file')
const fileString = parse(fileStream).then(result => result.toString())
 
// From a path
const fileString = parse('./path/to/file').then(result => result.toString())

And, if you want to save it to a file:

import {parse} from 'protots'
import fs from 'fs'
 
// From a buffer
const fileBuffer = fs.readFileSync('path/to/file')
const fileString = parse(fileBuffer).then(result => result.toFile('your/file/path.ts'))
 
// From a stream
const fileStream = fs.createReadStream('path/to/file')
const fileString = parse(fileStream).then(result => result.toFile('your/file/path.ts'))
 
// From a path
const fileString = parse('./path/to/file').then(result => result.toFile('your/file/path.ts'))

Options

ProtoTS has an options object wich allows you to define some behaviours you might want to change. These options are:

• keepComments?: boolean
  • Default: false
  • Description: Wether to keep the comment lines. This is false by default, since the output is not intented to be human-readable
• streamBehaviour?: 'strip' | 'generic' | 'native'
  • Default: native
  • Description: How to handle stream request and response types in RPCs. See Streams.
• stripEmtpyLines?: boolean
  • Default: true
  • Wether to remove emtpy lines (all of them). This is true by default, since the output is not intended to be human-readable

Streams

The included typescript Stream type is not generic and, apperently, it won't be. That leaves us with a problem: how to handle gRPC stream inputs and outputs?

This library offers three options, which are explained below, together with examples of the output produced by each of them given the following input:

rpc RouteChat(stream RouteNote) returns (stream RouteNote) {}

• Native (streamBehaviour: 'native'):

Uses the default, included typescript Stream types, wich will actually leave that stream's content with an any type.

Turns the example RPC into this:

routeChat (routeNoteStream: Stream): Stream

• Generic (streamBehaviour: 'generic'):

Uses ts-stream's Stream types, which are generic.

Turns the example RPC into this:

routeChat (routeNoteStream: Stream<RouteNote>): Stream<RouteNote>

Important Note: this depends on the manual addition, by you, of the ts-stream package to your project's dependencies, since ts-stream is a peer dependency

• Strip (streamBehaviour: 'strip'):

Does not handle input and output as streams, assumes that one request will come and be returned at a time.

Turns the example RPC into this:

routeChat (routeNote: RouteNote): RouteNote

Example file

Take this as an example protobuf file (taken from gRPC's repository):

// Copyright 2015 gRPC authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
syntax = "proto3";
 
option java_multiple_files = true;
option java_package = "io.grpc.examples.routeguide";
option java_outer_classname = "RouteGuideProto";
option objc_class_prefix = "RTG";
 
package routeguide;
 
// Interface exported by the server.
service RouteGuide {
  // A simple RPC.
  //
  // Obtains the feature at a given position.
  //
  // A feature with an empty name is returned if there's no feature at the given
  // position.
  rpc GetFeature(Point) returns (Feature) {}
  // A server-to-client streaming RPC.
  //
  // Obtains the Features available within the given Rectangle.  Results are
  // streamed rather than returned at once (e.g. in a response message with a
  // repeated field), as the rectangle may cover a large area and contain a
  // huge number of features.
  rpc ListFeatures(Rectangle) returns (stream Feature) {}
  // A client-to-server streaming RPC.
  //
  // Accepts a stream of Points on a route being traversed, returning a
  // RouteSummary when traversal is completed.
  rpc RecordRoute(stream Point) returns (RouteSummary) {}
  // A Bidirectional streaming RPC.
  //
  // Accepts a stream of RouteNotes sent while a route is being traversed,
  // while receiving other RouteNotes (e.g. from other users).
  rpc RouteChat(stream RouteNote) returns (stream RouteNote) {}
}
 
// Points are represented as latitude-longitude pairs in the E7 representation
// (degrees multiplied by 10**7 and rounded to the nearest integer).
// Latitudes should be in the range +/- 90 degrees and longitude should be in
// the range +/- 180 degrees (inclusive).
message Point {
  int32 latitude = 1;
  int32 longitude = 2;
}
 
// A latitude-longitude rectangle, represented as two diagonally opposite
// points "lo" and "hi".
message Rectangle {
  // One corner of the rectangle.
  Point lo = 1;
  // The other corner of the rectangle.
  Point hi = 2;
}
 
// A feature names something at a given point.
//
// If a feature could not be named, the name is empty.
message Feature {
  // The name of the feature.
  string name = 1;
  // The point where the feature is detected.
  Point location = 2;
}
 
// A RouteNote is a message sent while at a given point.
message RouteNote {
  // The location from which the message is sent.
  Point location = 1;
  // The message to be sent.
  string message = 2;
}
 
// A RouteSummary is received in response to a RecordRoute rpc.
//
// It contains the number of individual points received, the number of
// detected features, and the total distance covered as the cumulative sum of
// the distance between each point.
message RouteSummary {
  // The number of points received.
  int32 point_count = 1;
  // The number of known features passed while traversing the route.
  int32 feature_count = 2;
  // The distance covered in metres.
  int32 distance = 3;
  // The duration of the traversal in seconds.
  int32 elapsed_time = 4;
}

ProtoTS will (with the default options) convert it into:

export namespace Routeguide {
export interface RouteGuideService {
getFeature (point: Point): Feature
listFeatures (rectangle: Rectangle): Feature
recordRoute (point: Point): RouteSummary
routeChat (routeNote: RouteNote): RouteNote
}
export interface PointService {
latitude?: number
longitude?: number
}
export interface RectangleService {
lo?: Point
hi?: Point
}
export interface FeatureService {
name?: string
location?: Point
}
export interface RouteNoteService {
location?: Point
message?: string
}
export interface RouteSummaryService {
pointCount?: number
featureCount?: number
distance?: number
elapsedTime?: number
}
}
 

Note that indentation was not preserved, since the generated output should not be considered a source code file, and should not be edited by hand, and thus doesn't need to be human-readable