I develop Rest API with scala and play framework.
In my product controller, I do validation of parameters received.
In case they fail from some reason, I would like to response with BadRequest in the middle of the function and not in the last line as scala works..
In the code below - Code continues running to the Ok line.. which is wrong, I want to return !
def getProduct(lang: String, t: String, ids: String) = Action {
val productIdsList = ids.split(",").toList
if (productIdsList.length.equals(1) && productIdsList(0).equals("")) //Validate input params are product Ids and not empty !
{
var errorResponse:ErrorResponse[String] = ErrorResponse(ErrorCode.GeneralError, "No products IDs", 500)
BadRequest(Json.toJson(errorResponse))//maybe return BadRequest(Json.toJson(errorResponse) ??
}
val results = productService.getProducts(GetProductsRequest(lang,t,productIdsList));
Ok(Json.toJson(results))
// TODO: handle error
}
If implemented as:
return BadRequest(...)
It reply with error:
"method getProduct has return statement; needs result type"
I Understand this is bad practice, so what is the best practice for quitting the function without finishing it (and not throwing exceptions..)
Just put an else branch, so there's nowhere to continue:
def getProduct(lang: String, t: String, ids: String) = Action {
val productIdsList = ids.split(",").toList
if (productIdsList.length.equals(1) && productIdsList(0).equals("")){ //Validate input params are product Ids and not empty !
var errorResponse:ErrorResponse[String] = ErrorResponse(ErrorCode.GeneralError, "No products IDs", 500)
BadRequest(Json.toJson(errorResponse))//maybe return BadRequest(Json.toJson(errorResponse) ??
}else{
val results = productService.getProducts(GetProductsRequest(lang,t,productIdsList));
Ok(Json.toJson(results))
// TODO: handle error
}
}
Related
Imagine the following chain where a user wants to save a list of some sort:
var saveChain = userTappedSaveListSubject
.doOnNext { list -> Void in // create pdf version
let pdfFactory = ArticleListPDFFactory()
list.pdf = try pdfFactory.buildPDF(list)
try database.save(list)
}
.flatMap { list in
AuthorizedNetworking.shared.request(.createList(try ListRequestModel(list)))
.filter(statusCode: 201)
.map { _ in list }
}
.doOnNext { list in
list.uploaded = true
try database.save(list)
try Printer().print(list)
}
.materialize()
.share()
On every operator in the chain errors can occur, which would terminate the stream and the user would be unable to retry saving and printing the list (the whole chain gets disposed).
In the end the user should see either a "success" or "failure" screen by binding the observable to a textField:
Observable.of(
saveChain.elements().map { _ in
("List saved!", subtitle: "Saving successfull")
},
saveChain.errors().map { error in
("Error!", subtitle: error.localizedDescription)
})
.merge()
How should the error be handled?
Here's the obvious fix:
let saveChain = userTappedSaveListSubject
.flatMap { list in
Observable.just(list)
.do(onNext: { list -> Void in // create pdf version
let pdfFactory = ArticleListPDFFactory()
list.pdf = try pdfFactory.buildPDF(list)
try database.save(list)
})
.flatMap { list in
AuthorizedNetworking.shared.request(.createList(try ListRequestModel(list)))
.filter(statusCode: 201)
.map { _ in list }
}
.do(onNext: { list in
list.uploaded = true
try database.save(list)
try Printer().print(list)
})
.materialize()
}
.share()
However, there are a host of problems with this code because of the mixed paradigms.
You are passing around a mutable class inside your Observables. This is problematic because it's a functional paradigm so the system expects the contained type to be either a struct/enum or an immutable class.
Your reliance on side effects to load up said mutable class object again is quite odd and against the paradigm.
I have a route, that will unmarshell the incoming entity into a case class.
final case class ProducerMessage(topic: String, event: String, data: spray.json.JsObject)
object ProducerServer {
private val route: Route =
path("producer") {
post {
entity(as[ProducerMessage]) { msg =>
//complete(HttpEntity(ContentTypes.`text/html(UTF-8)`, "<h1>Say hello to akka-http</h1>"))
}
}
}
def create(): Future[ServerBinding] {
Http().bindAndHandle(route, getServerIp, getServerPort)
}
}
How do I know, if the process of unmarshell was successfully or not?
When received data is not a valid JSON format, what happen then?
When you have entity(as[T]) the as[T] is used to summon instance of FromRequestUnmarshaller[T] - then depending of the result returned by unmarshaller, entity will continue with passing on T into closure, or if it will fail the Directive.
If you need to do something with the information about rejection, then there are methods like recover, which you can call before apply.
For instance:
entity(as[ProducerMessage])
.map(Right(_): Either[Seq[Rejection], ProducerMessage])
.recover { rejections =>
provide(Left(rejections): Either[Seq[Rejection], ProducerMessage]))
} { value: Either[Seq[Rejection], ProducerMessage] =>
...
}
should let you see if input was rejected and recover/handle it manually.
I'm trying to write a function using Swift and Vapor but I don't understand why one statement gets printed before the other:
// Logout user
func logout(_ req: Request) throws -> Future<APIResponseMessage> {
let userID = self.checkAccessToken(req: req)
// Delete access token here
let apiResponseMessage = APIResponseMessage()
apiResponseMessage.message = "success"
apiResponseMessage.userID = userID
return apiResponseMessage.create(on: req)
}
func checkAccessToken(req: Request) -> Int {
let bearerAuthorization = req.http.headers.bearerAuthorization
guard let _bearerAuthorization = bearerAuthorization else {
// Works fine
print("no bearer incluced")
return 0
}
let _ = AccessToken.query(on: req).filter(\.accessToken == _bearerAuthorization.token).first().map(to: Int.self) { queriedAccessToken in
// This should be first
print("This gets printed second")
return queriedAccessToken!.userID!
}
// This should be second
print("This gets printed first")
return 0
}
Can anyone tell me how to make the second print statement wait until the first one is completed?
Right now it's causing my logout function to run with userID == 0 when this shouldn't be the case
As #nathan said, this is due to your code being async. Your .map callback is like the closure you pass into to a URLSession.dataTask when making request's to an external API for an iOS app.
Vapor uses a slightly different async model then what you use in iOS though, using promises and futures instead of callback closures. You can read about them in the docs.
In your case, you want to return the userID you get from the AccessToken query. To do this, you first need to change your method's return type from Int to Future<Int>. Then, instead of assigning the result of the .map call to _, you can return it from the method:
func checkAccessToken(req: Request) -> Future<Int> {
let bearerAuthorization = req.http.headers.bearerAuthorization
guard let _bearerAuthorization = bearerAuthorization else {
return req.future(0)
}
return AccessToken.query(on: req).filter(\.accessToken == _bearerAuthorization.token).first().map(to: Int.self) { queriedAccessToken in
return queriedAccessToken!.userID!
}
}
I would suggest you look into error handling for your queriedAccessToken and userID values so you aren't force-unwrapping them.
I am trying to define a webservice, using Scalatra, where the parameters are passed in in the body, preferably as JSON, not having everything on the url, as I have it now.
So, I would like this test to pass, but the commented out code is what passes currently. The non-commented code isn't JSON, but I also am not certain how I would pass JSON for testing, as put requires an Iterable in the second parameter.
class WebAppSpec extends MutableScalatraSpec {
addServlet(classOf[WebApp], "/*")
"PUT /phaseupdate" should {
"return status 200" in {
//put("/phaseupdate/test1/address1/starting/10") {
put("/phaseupdate", Map("filename" -> "test1", "entryaddress" -> "address1","name" -> "starting","percentcomplete" -> "10")) {
status must_== 200
}
}
}
My current definition, which is wrong, is:
put("/phaseupdate/:filename/:entryaddress/:name/:percentcomplete") {
val filename = params("filename")
val entryaddress = params("entryaddress")
val name = params("name")
val percentcomplete = params("percentcomplete")
So how do I define my put service to just call it with PUT /phaseupdate and have the parameters in the body?
I am trying to limit what is going into the webserver access log, basically.
The solution is to do this:
put("/phaseupdate") {
val filename = if (params("filename").indexOf('.') > -1) params("filename").substring(0, params("filename").indexOf('.')) else params("filename")
val entryaddress = params("entryaddress")
val name = params("name")
val percentcomplete = params("percentcomplete")
Basically, params() can read in what was passed.
The specs2 test is, and if this is followed by the get it returns the correct information.
"PUT /phaseupdate" should {
"return status 200" in {
put("/phaseupdate", Map("filename" -> "test1", "entryaddress" -> "address1", "name" -> "starting", "percentcomplete" -> "10")) {
status must_== 200
}
}
}
I am using databinder dispatch for making HTTP requests which works nicely, as long as the web server returns a 404.
If the request fails, the web server returns a 403 status code and provides a detailed error message in the response body as XML.
How to read the xml body (regardless of the 403), e.g. how can I make dispatch ignore all 403 errors?
My code looks like this:
class HttpApiService(val apiAccount:ApiAccount) extends ApiService {
val http = new Http
override def baseUrl() = "http://ws.audioscrobbler.com/2.0"
def service(call:Call) : Response = {
val http = new Http
var req = url(baseUrl())
var params = call.getParameterMap(apiAccount)
var response: NodeSeq = Text("")
var request: Request = constructRequest(call, req, params)
// Here a StatusCode exception is thrown.
// Cannot use StatusCode case matching because of GZIP compression
http(request <> {response = _})
//returns the parsed xml response as NodeSeq
Response(response)
}
private def constructRequest(call: Call, req: Request, params: Map[String, String]): Request = {
val request: Request = call match {
case authCall: AuthenticatedCall =>
if (authCall.isWriteRequest) req <<< params else req <<? params
case _ => req <<? params
}
//Enable gzip compression
request.gzip
}
}
I believe something like this works:
val response: Either[String, xml.Elem] =
try {
Right(http(request <> { r => r }))
} catch {
case dispatch.StatusCode(403, contents) =>
Left(contents)
}
The error will be in Left. The success will be in Right. The error is a String that should contain the XML response you desire.
If you need more, I believe you can look at HttpExecutor.x, which should give you full control. It's been a while since I've used dispatch, though.
Also, I'd suggest using more val's and less var's.