React Native gRPC Swift/Java bridge generator

If you are developing React Native app and using gRPC for backend communication when you need to bind native gRPC Swift/Android packages and communicate between native and javascript.
React Native accepts only Dictionaries and Arrays with primitive types.

Features

- [x] Generate Swift Unary calls code for JS mappings
- [x] Generate iOS Swift bridge header
- [x] Generate Typescript interfaces for JS/TS
- [ ] Generate Swift Streaming calls code for JS mappings
- [ ] Generate Android Unary code for JS mappings
- [ ] Generate Android Streaming code for JS mappings

$3

1. Lets say we have proto
``
message Book {
int64 isbn = 1;
string title = 2;
string author = 3;
int32 pages = 4;
bool isActivate = 5;
BookDetails details = 6;
}

message GetTypesRequest {
double dbl = 1;
float flt = 2;
int32 intr32 = 3;
int64 intr64 = 4;
uint32 uintr32 = 5;
uint64 uintr64 = 6;
sint32 suint32 = 7;
sint64 suint64 = 8;
fixed32 fxd32 = 9;
fixed64 fxd64 = 10;
sfixed32 sfxd32 = 11;
sfixed64 sfxd64 = 12;
bool bln = 13;
string str = 14;
bytes bytx = 15;
repeated Book books = 16;
Book book = 17;
}

message GetTypesResponse {
double dbl = 1;
float flt = 2;
int32 intr32 = 3;
int64 intr64 = 4;
uint32 uintr32 = 5;
uint64 uintr64 = 6;
sint32 suint32 = 7;
sint64 suint64 = 8;
fixed32 fxd32 = 9;
fixed64 fxd64 = 10;
sfixed32 sfxd32 = 11;
sfixed64 sfxd64 = 12;
bool bln = 13;
string str = 14;
bytes bytx = 15;
repeated Book books = 16;
Book book = 17;
}

service BookService {
rpc GetTypes (GetTypesRequest) returns (GetTypesResponse) {}
}

`

2. Now if you want to call GetTypes method from javascript you need to write all these mappings

`swift
@objc(BookService)
class BookService: NSObject, GrpcService {

@objc func GetTypes(_ req$: [String: Any], resolve: RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void {
let svc = BookServiceClient()
var req = Book_GetTypesRequest()

// request mapping
req.dbl = req$["dbl"] as? Double ?? 0
req.flt = req$["flt"] as? Float ?? 0
req.intr32 = Int32(req$["intr32"] as? Int ?? 0)
req.intr64 = Int64(req$["intr64"] as? Int ?? 0)
req.uintr32 = UInt32(req$["uintr32"] as? Int ?? 0)
req.uintr64 = UInt64(req$["uintr64"] as? Int ?? 0)
req.suint32 = Int32(req$["suint32"] as? Int ?? 0)
req.suint64 = Int64(req$["suint64"] as? Int ?? 0)
req.fxd32 = UInt32(req$["fxd32"] as? Int ?? 0)
req.fxd64 = UInt64(req$["fxd64"] as? Int ?? 0)
req.sfxd32 = Int32(req$["sfxd32"] as? Int ?? 0)
req.sfxd64 = Int64(req$["sfxd64"] as? Int ?? 0)
req.bln = req$["bln"] as? Bool ?? false
req.str = req$["str"] as? String ?? ""
req.bytx = req$["bytx"] as? Data ?? Data()
if let arr = req$["books"] as? [[String: Any]] {
for item in arr {
if let books_Book$ = item as? [String: Any] {
var books_Book = Book()
books_Book.isbn = Int64(books_Book$["isbn"] as? Int ?? 0)
books_Book.title = books_Book$["title"] as? String ?? ""
books_Book.author = books_Book$["author"] as? String ?? ""
books_Book.pages = Int32(books_Book$["pages"] as? Int ?? 0)
books_Book.isActivate = books_Book$["isActivate"] as? Bool ?? false
if let details_BookDetails$ = books_Book$["details"] as? [String: Any] {
var details_BookDetails = BookDetails()
details_BookDetails.pages = Int32(details_BookDetails$["pages"] as? Int ?? 0)
books_Book.details = details_BookDetails
}
req.books.append(books_Book)
}
}
}
if let book_Book$ = item["book"] as? [String: Any] {
var book_Book = Book()
book_Book.isbn = Int64(book_Book$["isbn"] as? Int ?? 0)
book_Book.title = book_Book$["title"] as? String ?? ""
book_Book.author = book_Book$["author"] as? String ?? ""
book_Book.pages = Int32(book_Book$["pages"] as? Int ?? 0)
book_Book.isActivate = book_Book$["isActivate"] as? Bool ?? false
if let details_BookDetails$ = book_Book$["details"] as? [String: Any] {
var details_BookDetails = BookDetails()
details_BookDetails.pages = Int32(details_BookDetails$["pages"] as? Int ?? 0)
book_Book.details = details_BookDetails
}
req.book = book_Book
}
// end request mapping

do {
let res = try svc.GetTypes(req)
var res$: [String: Any] = [:]

// response mapping
res$["dbl"] = res.dbl
res$["flt"] = res.flt
res$["intr32"] = res.intr32
res$["intr64"] = res.intr64
res$["uintr32"] = res.uintr32
res$["uintr64"] = res.uintr64
res$["suint32"] = res.suint32
res$["suint64"] = res.suint64
res$["fxd32"] = res.fxd32
res$["fxd64"] = res.fxd64
res$["sfxd32"] = res.sfxd32
res$["sfxd64"] = res.sfxd64
res$["bln"] = res.bln
res$["str"] = res.str
res$["bytx"] = res.bytx
var books$: [[String: Any]] = []
for item in res.books {
var _books_Book = item
var _books_Book$: [String: Any] = [:]
_books_Book$["isbn"] = _books_Book.isbn
_books_Book$["title"] = _books_Book.title
_books_Book$["author"] = _books_Book.author
_books_Book$["pages"] = _books_Book.pages
_books_Book$["isActivate"] = _books_Book.isActivate
var _details_BookDetails = _books_Book.details
var _details_BookDetails$: [String: Any] = [:]
_details_BookDetails$["pages"] = _details_BookDetails.pages
_books_Book$["details"] = _details_BookDetails$
books$.append(_books_Book$)
}
res$["books"] = books$
var _book_Book = res.book
var _book_Book$: [String: Any] = [:]
_book_Book$["isbn"] = _book_Book.isbn
_book_Book$["title"] = _book_Book.title
_book_Book$["author"] = _book_Book.author
_book_Book$["pages"] = _book_Book.pages
_book_Book$["isActivate"] = _book_Book.isActivate
var _details_BookDetails = _book_Book.details
var _details_BookDetails$: [String: Any] = [:]
_details_BookDetails$["pages"] = _details_BookDetails.pages
_book_Book$["details"] = _details_BookDetails$
res$["book"] = _book_Book$
// end response mapping

resolve(res$)
} catch {
reject("ERROR", error.localizedDescription, error)
}
}
}
`

3. rn-grpc-bridge generator can do it for you

$3

1. Install
`
yarn add rn-grpc-bridge --dev
`

2. Compile using protoc compiler
`shell
protoc \
--rn_out=${OUTDIR} \
--plugin=protoc-gen-rn=./node_modules/.bin/rn-grpc-bridge \
-I ./proto \
proto/*.proto
`

3. Initialize services from react native. See generate grpc_config.swift for call arguments.


`js
import { NativeModules, DebugService } from 'react-native';
import { DebugService, PingRequest } from './pb/debug_grpc_pb_types';

// inside some initial component
class InitialScreen {
async componentDidMount() {
const grpcConfig = NativeModules.GrpcConfig;

// init for local dev
await grpcConfig.initServices('localhost:9000', false, '');
// or for secure with TLS cert to staging/prod
// await grpcConfig.initServices('corp.staging.com', true, 'certname');

// it is also possible to set global for all services metadata
await grpcConfig.setMetadata({
'x-key': 'x-value',
'api-key': 'abc1'
});

// now we are ready to call grpc
const debugService: DebugService = NativeModules.DebugService;
const req: PingRequest = {
message: ping from react native ${new Date().getTime()}
};
const rsp = await debugService.ping(req);
console.log(rsp);
}
}
``

$3

See example which uses Docker image to run rn-grpc-bridge without any external library.