Vapor 3 - 发送HTTPRequest

Question

如何使用HTTPRequest结构在Vapor 3中发送API请求？

我尝试了以下代码的变体..

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)
}

编译错误Cannot convert value of type '(HTTPClient) -> EventLoopFuture<HTTPResponse>' to expected argument type '(HTTPClient) -> _'

我尝试了其他有用的代码变体。

Vapor 3 Beta Example Endpoint Request

let client = try req.make(Client.self)

let response: Future<Response> = client.get("http://example.vapor.codes/json")

我阅读并重新阅读：

• 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

你的问题是.map(to: HTTPResponse.self)。 Map需要定期将其结果转换为新结果，就像map数组一样。但是，map-closure的结果会返回EventLoopFuture<HTTPResponse>。这导致你的map函数返回EventLoopFuture<EventLoopFuture<HTTPResponse>>。

要避免这种复杂性，请使用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)
}

编辑：如果你想使用内容API，你可以这样做：

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返回Future<HTTPClient>，它映射到Future<HTTPResponse>而不是EventLoopFuture<HTTPResponse>。

如果你期待一个HTTPResponse使用HttpClient.send而不是HTTPClient.connect。

如果您期望多个HTTPResponses，那么.map(to: HTTPResponse.self)必须更改为正确映射到EventLoopFuture<HTTPResponse>