Using SwiftProtobuf with Vapor 3

1_Vapor+Proto.swift

import Vapor
import SwiftProtobuf
import Foundation

extension Request {
    public func decodeMessage<M: SwiftProtobuf.Message>(_ type: M.Type = M.self) throws -> M {
        let data = http.body.data ?? Data()

        if http.contentType == MediaType.json {
            return try M(jsonUTF8Data: data)
        }

        return try M(serializedData: data)
    }
}

extension SwiftProtobuf.Message {
    fileprivate func toHTTPResponse(json: Bool = false) throws -> HTTPResponse {
        var http = HTTPResponse(status: .ok)

        if json {
            http.contentType = MediaType.json
            http.body = try jsonUTF8Data().convertToHTTPBody()
        } else {
            http.contentType = MediaType(type: "application", subType: "x-protobuf")
            http.body = try serializedData().convertToHTTPBody()
        }

        return http
    }

    public func toResponse(on req: Request) throws -> Response {
        let json = req.http.accept.contains(where: { $0.mediaType == MediaType.json })

        return Response(http: try toHTTPResponse(json: json), using: req)
    }
}

extension Future {
    public func toResponse<M>(_ type: M.Type = M.self, on req: Request) -> Future<Response> where Expectation: SwiftProtobuf.Message {
        return map { try $0.toResponse(on: req) }
    }
}

2_routes_example.swift

router.get("test") { req -> Response in
    var profile = Proto_UserProfile()
    var user = Proto_User()
    user.nickname = "FooBar"
    user.firstName = "Foo"
    user.lastName = "Bar"
    profile.user = user

    return try profile.toResponse(on: req)
}

// Calling without an accept header: curl localhost:8080/test
// --> returns binary message

// Calling with accept header: curl localhost:8080/test -H "Accept: application/json"
// --> returns JSON
// {"user":{"nickname":"FooBar","firstName":"Foo","lastName":"Bar"}}