gRPC Protobuf Loader

A utility package for loading .proto files for use with gRPC, using the latest Protobuf.js package.
Please refer to protobuf.js' documentation
to understands its features and limitations.

Installation

``sh
npm install @grpc/proto-loader
`

Usage

`js
const protoLoader = require('@grpc/proto-loader');
const grpcLibrary = require('grpc');
// OR
const grpcLibrary = require('@grpc/grpc-js');

protoLoader.load(protoFileName, options).then(packageDefinition => {
const packageObject = grpcLibrary.loadPackageDefinition(packageDefinition);
});
// OR
const packageDefinition = protoLoader.loadSync(protoFileName, options);
const packageObject = grpcLibrary.loadPackageDefinition(packageDefinition);
`

The options parameter is an object that can have the following optional properties:

| Field name | Valid values | Description
|------------|--------------|------------
| keepCase | true or false | Preserve field names. The default is to change them to camel case.
| longs | String or Number | The type to use to represent long values. Defaults to a Long object type.
| enums | String | The type to use to represent enum values. Defaults to the numeric value.
| bytes | Array or String | The type to use to represent bytes values. Defaults to Buffer.
| defaults | true or false | Set default values on output objects. Defaults to false.
| arrays | true or false | Set empty arrays for missing array values even if defaults is false Defaults to false.
| objects | true or false | Set empty objects for missing object values even if defaults is false Defaults to false.
| oneofs | true or false | Set virtual oneof properties to the present field's name. Defaults to false.
| json | true or false | Represent Infinity and NaN as strings in float fields, and automatically decode google.protobuf.Any values. Defaults to false
| includeDirs | An array of strings | A list of search paths for imported .proto files.

The following options object closely approximates the existing behavior of grpc.load:

`js
const options = {
keepCase: true,
longs: String,
enums: String,
defaults: true,
oneofs: true
}
`

Generating TypeScript types

The proto-loader-gen-types script distributed with this package can be used to generate TypeScript type information for the objects loaded at runtime. More information about how to use it can be found in the @grpc/proto-loader TypeScript Type Generator CLI Tool proposal document. The arguments mostly match the load function's options; the full usage information is as follows:

`console
proto-loader-gen-types.js [options] filenames...

Options:
--help Show help [boolean]
--version Show version number [boolean]
--keepCase Preserve the case of field names
[boolean] [default: false]
--longs The type that should be used to output 64 bit
integer values. Can be String, Number
[string] [default: "Long"]
--enums The type that should be used to output enum fields.
Can be String [string] [default: "number"]
--bytes The type that should be used to output bytes
fields. Can be String, Array
[string] [default: "Buffer"]
--defaults Output default values for omitted fields
[boolean] [default: false]
--arrays Output default values for omitted repeated fields
even if --defaults is not set
[boolean] [default: false]
--objects Output default values for omitted message fields
even if --defaults is not set
[boolean] [default: false]
--oneofs Output virtual oneof fields set to the present
field's name [boolean] [default: false]
--json Represent Infinity and NaN as strings in float
fields. Also decode google.protobuf.Any
automatically [boolean] [default: false]
--includeComments Generate doc comments from comments in the original
files [boolean] [default: false]
-I, --includeDirs Directories to search for included files [array]
-O, --outDir Directory in which to output files
[string] [required]
--grpcLib The gRPC implementation library that these types
will be used with. If not provided, some types will
not be generated [string]
--inputTemplate Template for mapping input or "permissive" type
names [string] [default: "%s"]
--outputTemplate Template for mapping output or "restricted" type
names [string] [default: "%s__Output"]
--inputBranded Output property for branded type for "permissive"
types with fullName of the Message as its value
[boolean] [default: false]
--outputBranded Output property for branded type for "restricted"
types with fullName of the Message as its value
[boolean] [default: false]
--targetFileExtension File extension for generated files.
[string] [default: ".ts"]
--importFileExtension File extension for import specifiers in generated
code. [string] [default: ""]
`

$3

Generate the types:

`sh
$(npm bin)/proto-loader-gen-types --longs=String --enums=String --defaults --oneofs --grpcLib=@grpc/grpc-js --outDir=proto/ proto/*.proto
`

Consume the types:

`ts
import * as grpc from '@grpc/grpc-js';
import * as protoLoader from '@grpc/proto-loader';
import type { ProtoGrpcType } from './proto/example.ts';
import type { ExampleHandlers } from './proto/example_package/Example.ts';

const exampleServer: ExampleHandlers = {
// server handlers implementation...
};

const packageDefinition = protoLoader.loadSync('./proto/example.proto');
const proto = (grpc.loadPackageDefinition(
packageDefinition
) as unknown) as ProtoGrpcType;

const server = new grpc.Server();
server.addService(proto.example_package.Example.service, exampleServer);
``