Vapor 3 - 发送一个 HTTPRequest

Question

如何在 Vapor 3 中使用 HTTPRequest 结构发送 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) -> _'

我已经尝试过其他有效的代码变体。

Vapor 3 Beta Example Endpoint Request

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

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

我反复阅读：

• 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

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

如果您期望单个 HTTPResponse 使用 HttpClient.send 而不是 HTTPClient.connect。

如果您希望有多个 HTTPResponses，则必须更改 .map(to: HTTPResponse.self) 以正确映射到 EventLoopFuture<HTTPResponse>

Answer 2

您的问题是.map(to: HTTPResponse.self)。 Map 需要定期将其结果转换为新结果，就像您将 map 数组一样。但是，地图关闭的结果会返回 EventLoopFuture<HTTPResponse>。这会导致您的 map 函数返回 EventLoopFuture<EventLoopFuture<HTTPResponse>>。

为避免这种复杂性，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： 如果您想使用 Content API，您可以这样做：

let data = httpRes.flatMap(to: ExampleData.self) { httpResponse in
    let response = Response(http: httpResponse, using: req)
    return try response.content.decode(ExampleData.self)
}