Vapor 3 - send a HTTPRequest - vapor

Question

How do you send an API request in Vapor 3 with the HTTPRequest struct?
I tried variations of the following code..
var headers: HTTPHeaders = .init()
let body = HTTPBody(string: a)
let httpReq = HTTPRequest(
method: .POST,
url: URL(string: "/post")!,
headers: headers,
body: body)
let httpRes: EventLoopFuture<HTTPResponse> = HTTPClient.connect(hostname: "httpbin.org", on: req).map(to: HTTPResponse.self) { client in
return client.send(httpReq)
}
The compile error Cannot convert value of type '(HTTPClient) -> EventLoopFuture<HTTPResponse>' to expected argument type '(HTTPClient) -> _'
I have tried other variations of code that worked.
Vapor 3 Beta Example Endpoint Request
let client = try req.make(Client.self)
let response: Future<Response> = client.get("http://example.vapor.codes/json")
I read and re-read:
https://api.vapor.codes/http/latest/HTTP/Structs/HTTPRequest.html
https://api.vapor.codes/http/latest/HTTP/Classes/HTTPClient.html
https://docs.vapor.codes/3.0/http/client/

Answer 1

Your problem is .map(to: HTTPResponse.self). Map needs to transform its result into a new result regularly, like you would map an array. However, the result of your map-closure returns an EventLoopFuture<HTTPResponse>. This results in your map function returning an EventLoopFuture<EventLoopFuture<HTTPResponse>>.
To avoid this complexity, use flatMap.
var headers: HTTPHeaders = .init()
let body = HTTPBody(string: a)
let httpReq = HTTPRequest(
method: .POST,
url: URL(string: "/post")!,
headers: headers,
body: body)
let client = HTTPClient.connect(hostname: "httpbin.org", on: req)
let httpRes = client.flatMap(to: HTTPResponse.self) { client in
return client.send(httpReq)
}
EDIT:
If you want to use the Content APIs you can do so like this:
let data = httpRes.flatMap(to: ExampleData.self) { httpResponse in
let response = Response(http: httpResponse, using: req)
return try response.content.decode(ExampleData.self)
}

Answer 2

HTTPClient.connect returns Future<HTTPClient> and it is mapping to a Future<HTTPResponse> not a EventLoopFuture<HTTPResponse>.
If you're expecting a single HTTPResponse use HttpClient.send instead of HTTPClient.connect.
If you're expecting multiple HTTPResponses then .map(to: HTTPResponse.self) must be changed to properly map to a EventLoopFuture<HTTPResponse>