How combine data from several responses in Scala Play2? - scala

Question

I need do some requests to different URLs, get data from their responses and put this info in one list, but i have some misunderstanding in this theme.
1) for one request i do
def doRequest: Future[WSResponse] = {
client
.url("MY_URL")
.withRequestTimeout(5000)
.get()}
Then I parse json in response to List of my objects:
def list: Future[List[FoobarEntry]] = {
doRequest.map {
response => {
val json = response.json \ "foobar"
json.validate[List[FoobarEntry]] match {
case js:JsSuccess[List[FoobarEntry]]=>
js.get
case e:JsError => Logger.error(JsError.toFlatJson(e).toString()); List()
}
}
}}
I think that for several url i should write some look like
def doRequests: List[Future[WSResponse]] = {
List(client
.url("URL_1")
.withRequestTimeout(5000)
.get(),
client
.url("URL_2")
.withRequestTimeout(5000)
.get())}
But how parse this list of Future[WSResponse] like my def list: Future[List[FoobarEntry]]?

Answer 1

Since you put the future responses inside of a list, you will have to map each future response with the parsing logic that turns it into a FoobarEntry. Like so:
val responseFutures: List[Future[WSResponse]] = ???
val foobarFutures: List[Future[FoobarEntry]] =
responseFutures.map(future => future.map(response => parse(response)))
Now you have a list of future parsed responses, but to do something when all of them has arrived you will need to sequence that list:
val futureFoobars = Future.sequence(foobarFutures)
So, sequence helps you to get from C[Future[A]] to Future[C[A]]

Answer 2

Use for-comprehensions.
val request1 = client.url("URL_1").withRequestTimeout(5000).get()
val request2 = client.url("URL_2").withRequestTimeout(5000).get()
val result: Future[List[FoobarEntry]] = for {
res1: WSResponse <- request1
res2: WSResponse <- request2
} yield List(res1, res2).map(parse).flatten
def parse(response: WSResponse): List[FoobarEntry] = {
val json = response.json \ "foobar"
json.validate[List[FoobarEntry]] match {
case js:JsSuccess[List[FoobarEntry]]=>
js.get
case e:JsError => Logger.error(JsError.toFlatJson(e).toString())
List()
}